Background: Cotton(Gossypium hirsutum L.) is often grown in locations characterized by high atmospheric evaporative demand. It has been hypothesized that plants which resist hydraulic flow under this condition will limit water use and conserve soil water. Therefore, in a series of controlled environment experiments ten cotton cultivars were exposed to two di erent temperature and vapor pressure deficit(VPD) conditions(i.e., 38 °C, > 3 kPa and 32 °C,1～1.5 kPa) as well as a progressive soil drying. Then, individual di erences in shoot hydraulic conductance(K_(shoot)) was measured using a hydraulic conductance flow meter(HCFM). Physiological parameters were reported included leaf area, dry leaf weight, stomatal conductance(gs), and water use e ciency coe cient(WUE_k).Results: Di erences were observed in K_(shoot) among cultivars under the 38 °C, > 3 kPa but not the 32 °C, 1～1.5 kPa environment. Under the 38 °C, > 3 kPa environment, correlations were found between K_(shoot), stomatal conductance(g_s), VPD breakpoint, WUE_k, total leaf area, dry leaf weight, fraction transpirable soil water(FTSW) threshold, and slope of TR decline after FTSW threshold.Conclusion: Results show that the ability of some cotton cultivars to restrict water loss under high evaporative demand through early stomatal closure is associated with the cultivars' K_(shoot). The K_(shoot) is influential in the limitation of TR trait under high temperature and VPD.

Background: Cotton is the source of natural fibers globally, fulfilling 90% of the textile industry's requirements. However, fiber development is a complex biological process comprising four stages. Fiber develops from a single cell, and cell elongation is a vital process in fiber development. Therefore, it is pertinent to understand and exploit mechanisms underlying cell elongation during fiber development. A previous report about cell division control protein 42(CDC-42) with its key role in cell elongation in eukaryotes inspired us to explore its homologs Rho GTPases for understanding of cell elongation during cotton fiber development.Result: We classified 2 066 Rho proteins from 8 Gossypium species into 5 and 8 groups within A and D sub-genomes,respectively. Asymmetric evolution of Rho members was observed among five tetraploids. Population fixation statistics between two short and long fiber genotypes identified highly diverged regions encompassing 34 Rho genes in G. hirustum, and 31 of them were retained through further validation by genome wide association analysis(GWAS).Moreover, a weighted gene co-expression network characterized genome-wide expression patteren of Rho genes based on previously published transcriptome data. Twenty Rho genes from five modules were identified as hub genes which were potentially related to fiber development. Interaction networks of 5 Rho genes based on transcriptional abundance and gene ontology(GO) enrichment emphasized the involvement of Rho in cell wall biosynthesis, fatty acid elongation, and other biological processes.Conclusion: Our study characterized the Rho proteins in cotton, provided insights into the cell elongation of cotton fiber and potential application in cotton fiber improvement.

Background: Aphis gossypii Glover(Hemiptera: Aphididae), a worldwide polyphagous phloem-feeding agricultural pest, has three wing morphs(winged parthenogenetic female, gynopara, and male) in the life cycle. The exclusive males could fly from summer hosts to winter hosts, which are essential for gene exchanges of cotton aphid populations from di erent hosts or regions. However, the molecular mechanism of wing di erentiation of male in A. gossypii remains unclear.Results: Morphological observation of male A. gossypii showed that there is no distinct di erence in the external morphologies of the 1st and 2nd instar nymphs. The obvious di erentiation of wing buds started in the 3rd instar nymph and was visible via naked eyes in the 4th instar nymphal stage, then adult male emerged with full wings.According to morphological dynamic changes, the development of wings in males were divided into four stages:preliminary stage(the 1st instar to 2nd instar), prophase(the 3rd instar), metaphase(the 4th instar), anaphase(the 5th instar). Results of feeding behavior monitoring via EPG(electrical penetration graph) technology indicated that although the male cotton aphids had strong desire to feed(longer duration of C 55.24%, F 5.05% and Pd waves 2.56%), its feeding e ciency to summer host cotton was low(shorter E1 3.56% and E2 waves 2.63%). Dynamic transcriptome analysis of male aphid at 5 di erent developmental periods showed that in the 3rd instar nymph, the number of up-regulated DEGs was significant increased, and time-course gene transcriptional pattern analyses results also showed that numerous genes categorized in clusters 3, 5, and 8 had the highest expressed levels, which were consistent with morphological changes of wing buds. These results indicate that the 3rd instar nymph is the critical stage of wing bud di erentiation in males. Furthermore, through pathway enrichment analysis of DEGs and WGCNA,it revealed that the neuroactive ligand-receptor interaction, Ras signaling pathway, dopaminergic synapse, circadian entrainment and the corresponding hub genes of PLK1, BUB1, SMC2, TUBG, ASPM, the kinesin family members(KIF23,KIF20, KIF18-19) and the novel subfamily of serine/threonine(Aurora kinase A and Aurora kinase B) probably played an important role in the critical stage of wing bud di erentiation.Conclusion: This study explored morphological changes and genes transcriptional dynamics males in cotton aphid, revealed the phenomenon of low feeding e ciency of winged males on summer host cotton, and identified key signaling pathways and potential hub genes potentially involved in wing bud di erentiation of male in A. gossypii.

Background: The cotton crop is universally considered as protein and edible oil source besides the major contributor of natural fiber and is grown in tropical and subtropical regions around the world Unpredicted environmental stresses are becoming significant threats to sustainable cotton production, ultimately leading to a substantial irreversible economic loss. Mitogen-activated protein kinase(MAPK) is generally considered essential for recognizing environmental stresses through phosphorylating downstream signal pathways and plays a vital role in numerous biological processes.Results: We have identified 74 MAPK genes across cotton, 41 from G. hirsutum, 19 from G. raimondii, whereas 14 have been identified from G. arboreum. The MAPK gene-proteins have been further studied to determine their physicochemical characteristics and other essential features. In this perspective, characterization, phylogenetic relationship,chromosomal mapping, gene motif, cis-regulatory element, and subcellular localization were carried out. Based on phylogenetic analysis, the MAPK family in cotton is usually categorized as A, B, C, D, and E clade. According to the results of the phylogenic relationship, cotton has more MAPKS genes in Clade A than Clade B. The cis-elements identified were classified into five groups(hormone responsiveness, light responsiveness, stress responsiveness, cellular development, and binding site). The prevalence of such elements across the promoter region of these genes signifies their role in the growth and development of plants. Seven GHMAPK genes(GH＿A07G1527, GH＿D02G1138,GH＿D03G0121, GH＿D03G1517, GH＿D05G1003, GH＿D11G0040, and GH＿D12G2528) were selected, and specific tissue expression and profiling were performed across drought and salt stresses. Results expressed that six genes were upregulated under drought treatment except for GH＿D11G0040 which is downregulated. Whereas all the seven genes have been upregulated at various hours of salt stress treatment.Conclusions: RNA sequence and qPCR results showed that genes as di erentially expressed across both vegetative and reproductive plant parts. Similarly, the qPCR analysis showed that six genes had been upregulated substantially through drought treatment while all the seven genes were upregulated across salt treatments. The results of this study showed that cotton GHMPK3 genes play an important role in improving cotton resistance to drought and salt stresses. MAPKs are thought to play a significant regulatory function in plants' responses to abiotic stresses according to various studies. MAPKs' involvement in abiotic stress signaling and innovation is a key goal for crop species research, especially in crop breeding.

Background: Potassium(K) deficiency has become a common field production problem following the widespread adoption of Bacillus thuringiensis(Bt) transgenic cotton(Gossypium hirsutum L.) worldwide. The purpose of this study was to clarify whether the introduction of Bt gene directly reduces the K-use e ciency of cotton to induce K deficiency.Results: The cotton variety, Jihe 321(wild type, WT) and its two Bt(Cry1Ac)-transgenic overexpression lines(OE-29317, OE-29312) were studied in field with low soil-test K~+(47.8 mg·kg~(-1)). In the field with low soil-test K~+, only OE-29317 had less biomass and K~+ accumulation than the WT at some growth stages. Both Bt lines produced similar or even greater seed cotton yield than WT in the field. When the Bt gene(～ 70%) in OE-29317 and OE-29312 plants was silenced by virus-induced gene silencing(VIGS), the VIGS-Bt plants did not produce more biomass than VIGSgreen fluorescent protein(control) plants.Conclusions: The introduction of Bt gene did not necessarily hinder the K use e ciency of the cotton lines under this study.

Background: Under abiotic stress conditions, cotton growth is inhibited and yield losses are severe. Identification of calnexin family members and function analysis under abiotic stress laid the foundation for the screening of stressrelated candidate genes.Results: A total of 60 CNX family members have been identified in Gossypium hirsutum, G. barbadense, G. arboreum,and G. raimondii, and they were divided into two categories: CNX and CRT genes. Through the construction of a phylogenetic tree, they were subdivided into three classes. Further analysis of chromosome localization, conserved promoters, gene structure and selection under pressure showed that the family members were highly conserved in the evolution process. Analysis of cis-acting elements in the promoter regions showed that CNX family genes contain regulatory elements for growth and development, anaerobic, drought, defense and stress response, and plant hormones. Using RNA-seq data to study the expression pattern of GhCNX genes under cold, hot, salt stress and Polyethylene glycol, it was observed that the gene expression levels changed by di erent degrees under di erent stress conditions, indicating that GhCNX members were involved in the regulation of multiple biological stresses.Conclusion: This study provides an insight into the members of cotton CNX genes. The results of this study suggested that CNX family members play a role in defense against adversity and provide a foundation for the discovery of stress-related genes.

Background: Nucleobase–ascorbate transporters(NAT), synonymously called nucleobase–cation symporter 2(NCS2) proteins, were earlier reported to be involved in plant growth, development and resistance to stress. Previous studies concluded that s a polymorphic SNP associated with NAT12 was significant di erent between salt-tolerant and salt-sensitive materials of upland cotton. In current study, a comprehensive analysis of NAT family genes was conducted for the first time in cotton.Results: In this study, we discovered 32, 32, 18, and 16 NAT genes in Gossypium hirsutum, G. barbadense, G. raimondii and G. arboreum, respectively, which were classified into four groups(groups I–IV) based on the multiple sequence analysis. These GhNAT genes were unevenly distributed on At and Dt sub-genome in G. hirsutum. Most GhNAT members in the same group had similar gene structure characteristics and motif composition. The collinearity analysis revealed segmental duplication as well as tandem duplication contributing to the expansion of the GhNATs. The analysis of cis-acting regulatory elements of GhNATs showed that the function of GhNAT genes in cotton might be related to plant hormone and stress response. Under di erent conditions, the expression levels further suggested the GhNAT family genes were associated with plant response to various abiotic stresses. GhNAT12 was detected in the plasma membrane. And it was validated that the GhNAT12 gene played an important role in regulating cotton resistance to salt and drought stress through the virus-induced gene silencing(VIGS) analysis.Conclusions: A comprehensive analysis of NAT gene family was performed in cotton, including phylogenetic analysis, chromosomal location, collinearity analysis, motifs, gene structure and so on. Our results will further broaden the insight into the evolution and potential functions of NAT genes in cotton. Current findings could make significant contribution towards screening more candidate genes related to biotic and abiotic resistance for the improvement in cotton.

Background: The majority of attenuated total reflection Fourier transform infrared(ATR FT-IR) investigations of cotton are focused on the fiber tissue for biological mechanisms and understanding of fiber development and maturity, but rarely on other cotton biomass components. This work examined in detail the ATR FT-IR spectral features of various cotton tissues/organs at reproductive and maturation stages, analyzed and discussed their biological implications.Results: The ATR FT-IR spectra of these tissues/organs were analyzed and compared with the focus on the lower wavenumber fingerprinting range. Six outstanding FT-IR bands at 1 730, 1 620, 1 525, 1 235, 1 050 and 895 cm-1 represented the major Cycosidic =O stretching, protein Amide I, Amide II, the O–H/N–H deformation, the total C–O–C stretching and the β-gllinkage in celluloses, respectively, and impacted di erently between these organs with the two growth stages. Furthermore, the band intensity at 1 620, 1 525, 1 235, and 1 050 c m-1 were exclusively and significantly correlated to the levels of protein(Amide I bond), protein(Amide II bond), cellulose, and hemicellulose, respectively, whereas the band at 1 730 cm-1 was negatively correlated with ash content.Conclusions: The resulting observations indicated the capability of ATR FT-IR spectroscopy for monitoring changes, transportation, and accumulation of the major chemical components in these tissues over the cotton growth period. In other words, this spectral technology could be an e ective tool for physiological, biochemical, and morphological research related to cotton biology and development.

Background: The bollworm complex consisting of Helicoverpa armigera and Earias vittella is a major threat in cotton production globally. The habit of developing resistance to many insecticides including Bt transgenic cotton necessitates the exploration of an alternate strategy to manage bollworms. The entomopathogenic nematodes(EPN) Steinernema carpocapsae strain APKS2 and Heterorhabditis bacteriophora strains KKMH1 and TRYH1 at di erent concentrations of 1 × 10~9 infective juveniles(IJs)·hm~(-2), 2 × 10~9 IJsH. armige·hm~(-2), and 3 ra and E. vitte× 10~9 IJslla locat·hm~(-2) in 500 L of water were evaluated as a foliar spray in fields naturally infested with ed at Eastern Block and and Cotton Research Farm of Tamil Nadu Agricultural University, Coimbaotre, India during October 2010–February 2011 and October 2011–February 2012, respectively.Results: In general, all three tested EPN strains reduced the larval population of H. armigera and E. vittella; reduced square and boll damage; and subsequently increased cotton yield compared with the untreated control. The S. carpocapsae APKS2 is most e ective against H. armigera whereas both S. carpocapsae APKS2 and H. bacteriophora KKMH1 were equally e ective against E. vittella. The higher dose of 3 2 × 10~9 IJs·hm~(-2) was highly significant in the reduction of H. armigera larvae. However, the doses × 10~9 IJss·hm~(-2) and 3 × 10~9 IJs·hm~(-2) were equally e ective for E. vittella control. The S. carpocapsae APKS2 at 3 × 10~9 IJ·hm~(-2) caused a 62.2% reduction of H. armigera larvae, 34% reduction of square damage, 58.5% reduction of boll damage, and yielded 45.5% more seed cotton than the untreated control plots. In E. vittella infested field, S. carpocapsae strain APKS2 and H. bacteriophora strain KKMH1 at 2 60.6%～62.4% larva reduction, 68.4%～70.7% square damage reduction, 66.6%～69.9% bo× 10~9 IJsll damag·hm~(-2) resulted in e reduction and 45.9% yield increase over the untreated control. The e ective EPN treatments were comparable to the chemical insecticide chlorpyriphos 20% emulsifiable concentrate spraying at 2 mL·L-1.Conclusions: This study has shown that EPN have great potential in the management of the bollworm complex in cotton. Foliar spraying EPN strain S. carpocapsae(APKS2) at 3 at10 days interv× 10~9 IJsals are th·hm~(-2) and S. carpocapsae(APKS2) or H. bacteriophora(KKMH1) at 2 × 10~9 IJs·hm~(-2) five timese best for the management of H. armigera and E. vittella, respectively.

Background: Cotton(Gossypium spp.) is one of the most important economic crops worldwide, and its production plays an important role in the economy of many countries. Genetically modified herbicide-tolerant(GMHT) crops, which were developed to minimize the losses caused by weeds, have gradually become the most widely adopted genetically modified crops in the world due to their economic and environmental benefits. However, the potential ecological and environmental risks of GMHT crops have attracted extensive attention and controversy. Arthropod communities form a prominent part of the biodiversity of agroecosystems and are important indicators of environmental health. Elucidating the e ects of GMHT crops on the diversity of arthropod communities is necessary to ensure the safety of GMHT crops.Result: In this 2-year study, we investigated the potential impact of GMHT crops on arthropod communities. The GMHT cotton variety GGK2 with glyphosate tolerance and its near-isogenic non-GMHT variety K312 were used for the experimental groups. The Shannon diversity index(H), Simpson diversity index(D), Pielou evenness index(J), and principal co-ordinates analysis(PCoA) of the Bray–Curtis distance were used to evaluate the population dynamics and biodiversity of arthropods in cotton fields. No significant di erences were found between GGK2 and K312 in their total abundance of arthropod communities, and biodiversity indexes on most sampling dates. The arthropod composition in the GGK2 and K312 plots was similar. Sampling dates had a significant e ect on biodiversity indexes, whereas no clear tendencies related to cotton variety or cotton variety A revealed high similarity between the arthropod commu× sampling dates interaction were recorded. In addition, PConities in the plots of the GMHT cotton variety GGK2 and its near-isogenic variety K312.Conclusion: There was no obvious di erence in abundance, diversity indexes of arthropod communities between GMHT cotton variety GGK2 and its near-isogenic variety K312 under the small-scale planting regime.

Background: Cotton(Gossypium hirsutum), the major textile fiber crop of the world, is negatively a ected by salinity. It leads to the induction of adverse e ects on growth and development of cotton. The overall yield of cotton faces major drawback once they are grown in saline soil. To improve cotton salt tolerance, transgenic approach o ers a fast and e ective way but it relies on the availability of salt tolerance genes.Results: In this study, we have reported the evaluation of ThST103, a homologue of Arabidopsis ozone-induced protein(AtOZI1) in Thellungiella halophila, in enhancing salt tolerance in cotton. Overexpression of ThST103 enabled cotton plants to germinate and grow better than the wild types under salt stress. The transgenic lines showed enhanced survival rate in the saline environment and experienced less oxidative damage compared with the wild types. In the field, the transgenic cotton lines produced higher yield than the wild type in saline soil. Transcriptomic comparison analyses of Th ST103 overexpression lines versus the wild type revealed upregulated genes enriched in salt stress tolerance and ion homeostasis.Conclusions: Our results demonstrate that Th ST103 has the capability to improve salt tolerance in cotton. It can be used in cotton breeding for salt tolerance cultivars.

Background:Cotton production in China is challenged by high labor input including manual topping(MT).Recently,to replace MT in the Xinjiang cotton region of China,mepiquat chloride(MC) was applied once more than the traditional multiple-application;this was designated as chemical topping(CT),but it is unclear whether the amount of irrigation needs to be adjusted to accommodate CT.Results:The main plots were assigned to three drip irrigation amounts [300(I_1),480(I_2),and 660(I_3) mm],and the subplots were assigned to the CT treatments [450(MC_1),750(MC_2),and 1 050(MC_3) mL·hm~(-2) 25% MC] with MT as a control that was performed after early bloom.The optimum drip irrigation amount for CT was explored based on leaf photosynthesis,chlorophyll fluorescence,biomass accumulation,and yield.There were significant influences of drip irrigation,topping treatments and their interaction on chlorophyll fluorescence characteristics,gas exchange parameters and biomass accumulation characteristics as well as yield.The combination of I_2 and MC_2(I_2 MC_2) performed best.Compared with I_2 MT,the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),and photochemical quenching coefficient(qP) of I_2 MC_2 significantly increased by 4.0%～7.2%,6.8%～17.1 %.5.2%～17.6%,and 4.8%～9.6%,respectively,from the peak flowering to boll opening stages.Moreover,I_2 MC_2 showed fast reproductive organ biomass accumulation and the highest seed cotton yield;the latter was 6.6%～12.8% higher than that of I_2 MT.Further analysis revealed that a 25% MC emulsion in water(MCEW) application resulted in yield improvement by increasing Pn,φPSⅡ,and qP to promote biomass accumulation and transport to reproductive organs.Conclusion:The results showed that the 480 mm drip irrigation combined with 750 mL·hm~(-2) MC increased the rate of dry matter accumulation in reproductive organs by increasing Pn,φPSⅡ,and qP to improve photosynthetic performance,thus achieving higher yield.

Background: The diversified and high value-added utilization of cotton by products can promote the sustainable development of modern agriculture. Di erences in potential nutrients among varieties can be explained by variations in the composition and abundance of fatty acids, polyphenols, carbohydrates, amino acids, and organic acids. Therefore, the analysis of metabolite species and relationships in cottonseed is meaningful for the development of cotton byproducts.Results: In this study, the metabolomes of three representative cotton cultivars of di erent species were compared using untargeted GC-TOF/MS analysis. A total of 263 metabolites were identified from 705 peaks, and their levels were compared across cultivars. Principal component analysis and OPLS-DA clearly distinguish these samples based on metabolites. There were significant di erences in the contents of amino acids, carbohydrates, organic acids, flavonoids, and lipids in G. hirsutum TM-1 compared with G. arboreum Shixiya1 and G. barbadense Hai7124. Notably, the bioactive nutrient compound catechin obtained from the di erential metabolites significantly accumulated in TM-1. Furthermore, a comprehensive analysis using catechin and oil-related traits was conducted in core collections of Gossypium hirsutum. The results revealed the reliability of the GC-TOF/MS analysis, as well as that catechin content has a negative association with myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, arachidic acid, and total fatty acids.Conclusion: These findings suggest that untargeted GC-TOF/MS analysis could provide a new method for investigating the underlying plant biochemistry of nutrient variation in cottonseed, and that catechin content has a negative association with oil-related traits in cottonseed. This study may pave the way to exploit the value of cotton byproducts.

Background: The utilization of heterosis has greatly improved the productivity of cotton worldwide. However, a major constraint for the large-scale promotion of F1 hybrid cotton is artificial emasculation and pollination. This study proposed the potential utilization of F2 hybrids to improve upland cotton production through a comparative evaluation of hybrid generations.Results: Eight upland cotton varieties were analyzed and crosses were made according to NCII incomplete diallel cross-breeding design in two cotton belts of China. Variance analysis revealed significant di erences in agronomic, yield, and fiber quality in both generations and environments. The broad-sense heritability of agronomic and yield traits was relatively higher than quality traits. Furthermore, the narrow-sense heritability of some traits was higher in F2 than in the F1 generation in both cotton belts. Overall, parental lines Zhong901, ZB, L28, and Z98 were observed with maximum combining ability while combinations with strong special combining ability were ZB n both generations. However,× DT, L28 × Z98, and ZB × 851. The yield traits heterosis was predominant i the level of heterosis was altered with trait, hybrid combination, generation, and environment. Interestingly, L28 × Z98 performed outstandingly in Anyang. Its lint yield(LY) was 24.2% higher in F_1 and 11.6% in F_2 than that of the control Ruiza 816. The performance of SJ48 × Z98 was excellent in Aral which showed 36.5% higher LY in F_1 and 10.9% in F_2 than control CCRI 49. Further results revealed most hybrid combinations had shown a low level of heterosis for agronomic and fiber quality traits in both generations. Comparatively, ZB otton belts. It is feasible to scree× DT and L28 n strong hete× Z98 showed hybrid vigor for multiple traits in both generations and crosis hybrid combinations with fine fiber in early generations. In the two environments, the correlation of some traits showed the same trend, and the correlation degree of Anyang site was higher than that of Aral site, and the correlation of some traits showed the opposite trend. According to the performance of strong heterosis hybrid combinations in di erent environments, the plant type, yield and fiber traits associated with them can be improved according to the correlation.Conclusions: Through comparative analysis of variance, combining ability, and heterosis in F_1 and F_2 hybrids in different cotton belts, this study proposed the potential utilization of F2 hybrids to improve upland cotton productivity in China.

Background: The lateral root is one of the most important organs that constitute the root architecture system in plants. It can directly a ect the contact area between plants and soil and plays an important role in plant structural support and nutrient absorption. Optimizing root architecture systems can greatly increase crop yields. This study was designed to identify the molecular markers and candidate genes associated with lateral root development in cotton and to evaluate correlations with yield and disease traits.Result: The number of lateral roots for 14-day old seedlings was recorded for 215 Gossypium arboreum accessions. A correlation analysis showed that the number of lateral roots positively correlates with the sympodial branch node and seed index traits, but negatively correlates with lint percentage. A Genome-wide association study(GWAS) identified 18 significant SNPs with 19 candidate genes associated with the lateral root number. Expression analysis identified three genes(FLA12, WRKY29, and RBOHA) associated with lateral root development.Conclusion: GWAS analysis identified key SNPs and candidate genes for lateral root number, and genes of FLA12, WRKY29, and RBOHA may play a pivotal role in lateral root development in Asian cotton.

Background: Gossypium hirsutum(upland cotton) is one of the principal fiber crops in the world. Cotton yield is highly affected by abiotic stresses, among which salt stress is considered as a major problem around the globe. Transgenic approach is efficient to improve cotton salt tolerance but depending on the availability of salt tolerance genes.Results: In this study we evaluated salt tolerance candidate gene ST7 from Thellungiella halophila, encoding a homolog of Arabidopsis aluminum-induced protein, in cotton. Our results showed that ThST7 overexpression in cotton improved germination under NaCl stress as well as seedling growth. Our field trials also showed that ThST7 transgenic cotton lines produced higher yield under salt stress conditions. The improved salt tolerance of the transgenic cotton lines was partially contributed by enhanced antioxidation as shown by diaminobenzidine(DAB) and nitrotetrazolium blue chloride(NBT) staining. Moreover, transcriptomic analysis of ThST7 overexpression lines showed a significant upregulation of the genes involved in ion homeostasis and antioxidation, consistent with the salt tolerance phenotype of the transgenic cotton.Conclusions: Our results demonstrate that ThST7 has the ability to improve salt tolerance in cotton. The ThST7 transgenic cotton may be used in cotton breeding for salt tolerance cultivars.

Australian cotton production predominantly occurs on Vertisols. The average lint yield of cotton grown in Australia is 2 260–2 700 kg·hm~(-2), which is 2.5 to 3 times the world average. This high productivity per unit of land area requires e cient use of resources such as water and nutrients. However, high yields accelerate the export of nutrients such as phosphorus(P) in seed, depleting the soil reserves of P more than in other countries with lower cotton yields. Recent surveys of cotton industry indicate that P application rates should match seed P export(30～ 40 kg·hm~(-2)), but historical depletion within subsoil is still evident and is continuing. Depletion of soil P is typically more pronounced in the subsoil than in the topsoil(0～ 20 cm) where P fertiliser is applied, as cotton roots rely on these layers as important sources of plant available water and available P. This mismatch between zones of P uptake and resupply may increase stratification of available P in the soil profile. Recent studies showed that cotton responded poorly to banded applications of fertiliser P, while dispersal of fertiliser throughout the plant beds was more successful. Researchers have also observed sporadic cotton responses to applied P fertiliser in soils where available P concentrations were well above the previously determined critical concentrations indicative of fertiliser P responses in Australia. To sustain highyielding cotton production in Australia, a greater understanding of cotton root acquisition of applied P, as well as a re-examination of critical soil P concentrations for each production region are required.

Trifloxysulfuron(Envoke) is an acetolactate synthase-inhibitor herbicide and can be used to control many broadleaf weeds and nutsedges in cotton production.However,there is a lack of information on genotypic variation in response to the herbicide.In this field study,60 Pima(Gossypium barbadense L.) lines,122 Upland(G.hirsutum L.) lines,and 9 Upland x Pima segregating populations were divided into five tests(18 A,18 B,18 G,18 RB,and 18 HQ) to evaluate trifloxysulfuron tolerance at the 7-true leaf stage(42 days after planting) under the same field conditions in 201 8.Across the five tests,Pima cotton genotypes tested in this study did not show any visual crop injury based on percentage of plants with chlorosis at 6 days after treatment(DAT),indicating consistent and high levels of trifloxysulfuron tolerance.However,the response to trifloxysulfuron within U pland cotton is highly variable.While U pland cotton is overall more sensitive to trifloxysulfuron with crop injury up to 80% than Pima cotton,1 9 lines had injury below 5% including one line with no visual injury,and 19 lines had injury between 5% and 10%.In test 18 HQ with 15 transgenic Upland cultivars and 17 non-transgenic Upland lines,the analysis of variance detected a significant genotypic difference.The broad-sense heritability estimates for trifloxysulfuron tolerance based on crop injury at 6 DAT was 0.555,suggesting that trifloxysulfuron tolerance in U pland cotton is moderately heritable.This study represents the first report that Pima cotton and many Upland cotton lines are highly tolerant to trifloxysulfuron with no or little crop injury.

Background: Cotton(Gossypium hirsutum L.) is an important fiber crop in Bangladesh. Genetic diversity among the genotypes of a germplasm has a great importance for cotton breeding. An experiment was carried out at the experimental field of Cotton Research, Training and Seed Multiplication Farm, Sreepur, Gazipur during the cropping season of 2015-2016 with 100 genotypes to evaluate genetic diversity of cotton genotypes for short duration using field performance.Results: The genotypes under study were grouped into ten clusters through multivariate analysis using GENSTAT-5.Cluster III contained maximum number of genotypes(16) while cluster X contained the least number of genotypes(7).The inter cluster distances were larger than intra cluster distances in all cases suggesting wider genetic diversity among the genotypes of different clusters. The maximum and minimum inter cluster distances were observed between clusters II and V(10.78) and clusters VIII and IX(3.30), respectively. The results indicated diverse and close relationship among the genotypes of those clusters. Earliness index, single boll weight and days to boll opening showed the higher contribution to the genetic divergence among 19 characters.Conclusion: Based on the results of genetic diversity and earliness index, the genotypes from cluster Ⅱ could be used as parent in hybridization program for the development of short duration cotton variety.

Background: Verticillium wilt is a serious soil-borne vascular disease that causes major losses to upland cotton(Gossypium hirutum L.) worldwidely every year. The protein VIP1(VirE2 interaction protein 1), a bZIP transcription factor, is involved in plant response to many stress conditions, especially pathogenic bacteria. However, its roles in cotton response to Verticillium wilt are poorly understood.Results: The GbVIP1 gene was cloned from resistant sea-island cotton(G. barbadense) cv. Hai 7124. Expression of GbVIP1 was up-regulated by inoculation with Verticillium dahliae and exogenous treatment with ethylene. Results of virus-induced gene silencing suggested that silencing of GbVIP1 weakened cotton resistance to Verticillium wilt. The heterologous expression of GbVIP1 in tobacco showed enhanced resistance to Verticillium wilt. The PR1, PR1-like and HSP70 genes were up-regulated in GbVIP1 transgenic tobacco after Verticillium wilt infection.Conclusion: Our results suggested that GbVIP1 increased plant resistance to Verticillium wilt through up-regulating expressions of PR1, PR1-like, and HSP70. These results provide new approaches to improving resistance to Verticillium wilt in upland cotton and also have great potential for disease-resistance breeding of cotton.

Cotton(Gossypium spp.) contributes significantly to the economy of cotton-producing countries. Pakistan is the fourth-largest producer of cotton after China, the USA and India. The average yield of cotton is about 570.99 kg.hm~(-2) in Pakistan. Climate change and different biotic stresses are causing reduction in cotton production.Transgenic approaches have unique advantage to tackle all these problems. However, how to confer permanent resistance in cotton against insects through genetic modification, is still a big challenge to address. Development of transgenic cotton has been proven to be effective. But its effectiveness depends upon several factors, including heterogeneity, seed purity, diffusion of varieties, backcrossing and ethical concerns. Cotton biotechnology was initiated in Pakistan in 1992–1993 with a focus on acquiring cotton leaf curl virus(CLCuV)-resistant insect-resistant,and improving fiber quality. This review summarizes the use of molecular markers, QTLs, GWAS, and gene cloning for cotton germplasm improvement, particularly in Pakistan.

Background: RING-H2 finger E3 ligase(RH2FE3) genes encode cysteine-rich proteins that mediate E3 ubiquitin ligase activity and degrade target substrates. The roles of these genes in plant responses to phytohormones and abiotic stresses are well documented in various species, but their roles in cotton fiber development are poorly understood. To date, genome-wide identification and expression analyses of Gossypium hirsutum RH2FE3 genes have not been reported.Methods: We performed computational identification, structural and phylogenetic analyses, chromosomal distribution analysis and estimated K_a/K_s values of G. hirsutum RH2FE3 genes. Orthologous and paralogous gene pairs were identified by all-versus-all BLASTP searches. We predicted cis-regulatory elements and analyzed microarray data sets to generate heatmaps at different development stages. Tissue-specific expression in cotton fiber, and hormonal and abiotic stress responses were determined by quantitative real time polymerase chain reaction(qRT-PCR) analysis.Results: We investigated 140 G. hirsutum, 80 G. arboreum, and 89 G. raimondi putative RH2FE3 genes and their evolutionary mechanisms and compared them with orthologs in Arabidopsis and rice. A domain-based analysis of the G.hirsutum RH2FE3 genes predicted conserved signature motifs and gene structures. Chromosomal localization showed the genes were distributed across al G. hirsutum chromosomes, and 60 duplication events(4 tandem and 56 segmental duplications) and 98 orthologs were detected. cis-elements were detected in the promoter regions of G. hirsutum RH2FE3 genes. Microarray data and qR T-PCR analyses showed that G. hirsutum RH2FE3 genes were strongly correlated with cotton fiber development. Additional y, almost al the identified genes were up-regulated in response to phytohormones(brassinolide, gibberel ic acid(GA), indole-3-acetic acid(IAA), and salicylic acid(SA)) and abiotic stresses(cold, heat,drought, and salt).Conclusions: The genome-wide identification, comprehensive analysis, and characterization of conserved domains and gene structures, as wel as phylogenetic analysis, cis-element prediction, and expression profile analysis of G. hirsutum RH2FE3 genes and their roles in cotton fiber development and responses to plant hormones and abiotic stresses are reported here for the first time. Our findings wil contribute to the genome-wide analysis of putative RH2FE3 genes in other species and lay a foundation for future physiological and functional research on G. hirsutum RH2FE3 genes.

Background: Cotton fiber quality and seed composition play vital roles in the economics of cotton production systems and the cottonseed meal industry. This research aimed to examine the effects of different irrigation levels and planting geometries on fiber quality and seed composition of cotton(Gossypium hirsutum L.). We conducted a2-year study in 2018 and 2019 in a warm, humid area in the Southeast United States on Dundee silt loam soil.There were three irrigation treatments in the study. The treatments included irrigating every furrow, or full irrigation(FI), every alternate furrow, or half irrigation(HI), and no irrigation, or rain-fed(RF). Planting geometries were on ridges spaced 102 cm apart and either a single-row(SR) or twin-rows(TR).Results: The results of high-volume instrument(HVI), advanced fiber information systems(AFIS) and near-infrared reflectance spectroscopy(NIRS) showed that irrigation and planting treatments played a significant role in fiber quality and seed composition. Across irrigation treatments, significant differences were seen in fiber properties, including fineness, maturity ratio, micronaire, neps, short fiber, strength, uniformity, upper half mean length(UHML), upper quartile length by weight(UQLw), and yel owness(+b). Irrigation and planting geometry(PG) had a significant effect on micronaire, strength, and UHML while their interaction was significant only for micronaire. The micronaire was negatively affected by irrigation as FI-SR, FI-TR, HI-SR, and HI-TR recorded 11% ～ 12% lower over the RF-SR and TR treatments. The PG played a minor role in determining fiber quality traits like micronaire and nep count. Irrigation treatments produced significantly lower(3% ～ 4%) protein content than rain-fed, while oil content increased significantly(6% ～ 10%).Conclusions: The study results indicate a potential for improving cotton fiber and seed qualities by managing irrigation and planting geometries in cotton production systems in the Mississippi(MS) Delta region. The HI-TR system appears promising for lint and seed quality.

Journal of Cotton Research (JCR) represents a brand new start of a scientific forum to advance cotton research communication. JCR is affiliated with Institute of Cotton Research of Chinese Academy of Agricultural Sciences(ICR, CAAS) and China Association of Agricultural Science Societies (CAASS), benefiting from solid academic support. In partnership with the leading Open Access brand BMC (part of Springer Nature), JCR aims

Verticillium wilt, caused by the notorious fungal pathogen Verticillium dahliae, is one of the main limiting factors for cotton production. Due to the stable dormant structure microsclerotia, long-term variability and co-evolution with host plant, its pathogenicity mechanism is very complicated, and the interaction mechanism between pathogen and host plant is also unclear. So identification and functional analysis of the genes involved in the pathogenicity or virulence of this fungus will benefit to uncover the molecular pathogenic mechanism of V. dahliae. In this review, many multifunction genes covering microsclerotia development, pathogen infection, e ector proteins, transcription factors, horizontal gene transfer and trans-kingdom RNA silencing have been summarized to provide a theoretical basis to deep understand the molecular pathogenicity mechanism of V. dahliae and promote to e ectively control Verticillium wilt. Furtherly, these pathogenicity-related genes may be considered as targets for e ective control of Verticillium wilt in cotton.

Background: Upland cotton(Gossypium hirsutum) accounts for more than 90% of the annual world cotton output because of its high yield potential. However, yield and fiber quality traits often show negative correlations. We constructed four F2 populations of upland cotton, using two normal lines(4133 B and SGK9708) with high yield potential but moderate fiber quality and two introgression lines(Suyuan04–3 and J02–247) with superior fiber quality, and used them to investigate the genetic basis underlying complex traits such as yield and fiber quality in upland cotton. We also phenotyped eight agronomic and economic traits and mapped quantitative trait loci(QTLs).Results: Extensive phenotype variations and transgressive segregation were found across the segregation populations.We constructed four genetic maps of 585.97 centiMorgan(cM), 752.45 cM, 752.45 cM, and 1 163.66 cM, one for each of the four F2 populations. Fifty QTLs were identified across the four populations(7 for plant height, 27 for fiber quality and 16 for yield). The same QTLs were identified in different populations, including qBW4 and qBW2, which were linked to a common simple sequence repeat(SSR) marker, NAU1255. A QTL cluster containing eight QTLs for six different traits was characterized on linkage group 9 of the 4133 B × Suyuan04–3 population.Conclusions: These findings will provide insights into the genetic basis of simultaneous improvement of yield and fiber quality in upland cotton breeding.

Background: Cotton is mainly grown for its natural fiber and edible oil. The fiber obtained from cotton is the indispensable raw material for the textile industries. The ever changing climatic condition, threatens cotton production due to a lack of sufficient water for its cultivation. Effects of drought stress are estimated to affect more than 50% of the cotton growing regions. To elucidate the drought tolerance phenomenon in cotton, a backcross population was developed from G. tomentosum, a drought tolerant donor parent and G. hirsutum which is highly susceptible to drought stress.Results: A genetic map of 10 888 SNP markers was developed from 200 BC_2F_2 populations. The map spanned 4 191.3 centi-Morgan(c M), with an average distance of 0.104 7 c M, covering 51% and 49% of At and Dt sub genomes, respectively. Thirty stable Quantitative trait loci(QTLs) were detected, in which more than a half were detected in the At subgenome. Eighty-nine candidate genes were mined within the QTL regions for three traits:cell membrane stability(CMS), saturated leaf weight(SLW) and chlorophyll content. The genes had varied physiochemical properties. A majority of the genes were interrupted by introns, and only 15 genes were intronless,accounting for 17% of the mined genes. The genes were found to be involved molecular function(MF), cellular component(CC) and biological process(BP), which are the main gene ontological(GO) functions. A number of mi RNAs were detected, such as mi R164, which is associated with NAC and MYB genes, with a profound role in enhancing drought tolerance in plants. Through RT-q PCR analysis, 5 genes were found to be the key genes involved in enhancing drought tolerance in cotton. Wild cotton harbors a number of favorable alleles, which can be exploited to aid in improving the narrow genetic base of the elite cotton cultivars. The detection of 30 stable QTLs and 89 candidate genes found to be contributed by the donor parent, G. tomentosum, showed the significant genes harbored by the wild progenitors which can be exploited in developing more robust cotton genotypes with diverse tolerance levels to various environmental stresses.Conclusion: This was the first study involving genome wide association mapping for drought tolerance traits in semi wild cotton genotypes. It offers an opportunity for future exploration of these genes in developing highly tolerant cotton cultivars to boost cotton production.

Background:INDETERMINATE DOMAIN(IDD)transcription factors form one of the largest and most conserved gene families in plant kingdom and play important roles in various processes of plant growth and development,such as flower induction in term of flowering control.Till date,systematic and functional analysis of IDD genes remained infancy in cotton.Results:In this study,we identified total of 162 IDD genes from eight different plant species including 65 IDD genes in Gossypium hirsutum.Phylogenetic analysis divided IDDs genes into seven well distinct groups.The gene structures and conserved motifs of GhIDD genes depicted highly conserved exon-intron and protein motif distribution patterns.Gene duplication analysis revealed that among 142 orthologous gene pairs,54 pairs have been derived by segmental duplication events and four pairs by tandem duplication events.Further,Ka/Ks values of most of orthologous/paralogous gene pairs were less than one suggested the purifying selection pressure during evolution.Spatiotemporal expression pattern by qRT-PCR revealed that most of the investigated GhIDD genes showed higher transcript levels in ovule of seven days post anthesis,and upregulated response under the treatments of multiple abiotic stresses.Conclusions:Evolutionary analysis revealed that IDD gene family was highly conserved in plant during the rapid phase of evolution.Whole genome duplication,segmental as well as tandem duplication significantly contributed to the expansion of IDD gene family in upland cotton.Some distinct genes evolved into special subfamily and indicated potential role in the allotetraploidy Gossypium hisutum evolution and development High transcript levels of GhIDD genes in ovules illustrated their potential roles in seed and fiber development Further,upregulated responses of GhIDD genes under the treatments of various abiotic stresses suggested them as important genetic regulators to improve stress resistance in cotton breeding.

Gossypium, as the one of the biggest genera, the most diversity, and the highest economic value in field crops, is assuming an increasingly important role in studies on plant taxonomy, polyploidization, phylogeny, cytogenetics,and genomics. Here we update and provide a brief summary of the emerging picture of species relationships and diversification, and a set of the designations for individual genomes and chromosomes in Gossypium. This cytogenetic and genomic nomenclature will facilitate comparative studies worldwide, which range from basic taxonomic exploration to breeding and germplasm introgression.

Background: Nitrogen(N) is a required macronutrient for cotton growth and productivity. Excessive N fertilizers are applied in agriculture for crop yield maximization, which also generates environmental pollution. Improving crop N use efficiency(NUE) is the most economical and desirable way of reducing fertilizer application and environmental pollution. NUE has been an important issue in cotton. So far there is no report on cotton NUE improvement via transgenic approach. Nin-like proteins(NLP) are transcription factors regulating NUE. We previously demonstrated that At NLP7 improved NUE and biomass when overexpressed in Arabidopsis. However, it is not known whether At NLP7 can be used to improve NUE in crops.Results: To test the feasibility, we expressed At NLP7 in cotton and evaluated NUE and yield of the transgenic cotton in the field. Transgenic cotton showed improved NUE and yield under both low and high N conditions. In addition, plant biomass, amount of absorbed N, N contents, activities of N-assimilating enzymes, and the expression of N-related marker genes were significantly increased in transgenic cotton compared with the wild type control, suggesting that At NLP7 enhances NUE in cotton.Conclusion: Together, our results demonstrate that At NLP7 is a promising candidate to improve NUE and yield in cotton.