【目的】研究花铃期棉花黄萎病抗/感品种土壤细菌群落结构,了解抗/感品种土壤细菌群落结构与土壤理化性质之间的关系,为棉花黄萎病的监测与绿色生态防控打下理论基础。【方法】通过田间小区试验,以感病品种（鄂荆1号,EJ）和抗病品种（冀863,J863）为试验材料,采用实时荧光定量PCR（real-time PCR）和高通量测序（Illumina MiSeq）技术分别测定花铃期不同阶段（盛花期、开花后期和结铃期）土壤中大丽轮枝菌（Verticillium dahliae）数量和土壤细菌群落结构,结合冗余分析（RDA）明确细菌群落结构与土壤理化性质的相关性。【结果】棉花黄萎病的发生与土壤中大丽轮枝菌ITS基因拷贝数量存在不同程度的相关性,其中感病品种EJ的发病率和病情指数与土壤中病原菌数量呈正相关,而抗病品种J863的发病率和病情指数与病原菌数量相关性不大。除盛花期外,棉花开花后期和结铃期抗病品种J863土壤中的病原菌数量低于感病品种EJ。高通量测序分析表明,除开花后期,抗病品种J863在盛花期和结铃期的细菌丰富度Chao1和ACE指数均高于感病品种EJ。主成分分析表明,抗/感品种之间及其在花铃期不同阶段的土壤细菌群落结构存在差异。群落组成方面,在门水平上,感病品种EJ的部分优势菌群平均相对丰度低于抗病品种J863,如放线菌门（Actinobacteria）、芽单胞菌门（Gemmatimonadetes）、绿弯菌门（Chloroflexi）、拟杆菌门（Bacteroidetes）、硝化螺菌门（Nitrospirae）、Patescibacteria和装甲菌门（Armatimonadetes）,降低幅度分别为16.38%、4.05%、2.25%、6.58%、7.10%、20.60%和35.78%;在属水平上,感病品种EJ的部分优势菌群平均相对丰度低于抗病品种J863,包括鞘氨醇单胞菌属（Sphingomonas）、芽单胞菌属（Gemmatimonas）、Bryobacter、Iamia、Pseudarthrobacter、芽球菌属（Blastococcus）、红色杆菌属（Rubrobacter）、类诺卡氏属（Nocardioides）、Pontibacter、链霉菌属（Streptomyces）、Gemmatirosa、微单孢菌属（Micromonospora）和Solirubrobacter,下降幅度分别为5.09%、19.41%、13.79%、2.36%、10.78%、34.47%、46.76%、61.84%、52.75%、48.61%、74.79%、9.13%和26.42%。冗余分析（RDA）表明,土壤细菌群落结构受硝态氮（NO₃ ^--N）、速效磷（AP）、铵态氮（NH₄ ⁺-N）、无机磷（IP）、pH和有机质（OM）指标影响。【结论】土壤中大丽轮枝菌的数量与棉花抗/感品种黄萎病发生的相关性存在差异,感病品种黄萎病的发生程度与土壤中病原菌数量呈正相关。抗病品种在盛花期、开花后期和结铃期土壤的细菌群落结构优于感病品种,并且不同生育时期的优势菌群存在一定程度的差异。土壤中细菌多样性、相对丰度和组成受有机质、pH、氮素类型、速效磷等指标影响。同时,棉花不同生育时期对土壤中细菌群落结构有明显影响。

菊花枯萎病 (Fusarium oxysporum f. sp. chrysanthemi)是目前影响菊花产业发展的一种侵入土壤根部传播的病害。笔者利用Illumina MiSeq高通量测序技术探讨菊花患枯萎病的发病植株和菊花健康植株的土壤根际微生物群落结构的差异。结果表明，菊花枯萎病的发生对根际土菌落丰富度存在明显影响。健康菊花植株和患病菊花植株根际细菌OTU数分别是1831和1723个，两者共有为1661个，菊花健株根际土壤中细菌OTU总数比菊花病株增加6.23%，特有OTUs数是患病植株的2.74倍。从土壤根际群落结构的多样性水平上看，菊花患枯萎病植株低于菊花健康植株。Alpha多样性指数显示，菊花病株根际土壤的Shannon、Ace以及Chao1指数比健株降低1.60%、5.71%和6.62%。此外，菊花患枯萎病植株与健康植株在土壤细菌群落多样性的结构上也有明显差异，菊花健康植株根际土中，主要α-变形菌纲(α-proteobacteria)、芽孢杆菌纲(Bacilli)、绿弯菌纲(Chloroflexia)，其相对丰富度分别比病株高10.27%、1.51%、9.54%；在属水平上，病株根际土中芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)、节杆菌属(Arthrobacter)相对丰富度比健株分别低4.14%、0.45%、39.24%。上述结果说明，在菊花根际土中，细菌群落结构的改变以及物种多样性的降低是菊花枯萎病发生的关键因素，研究结果可为更早防治菊花枯萎病提供理论依据。

以4 份田间抗性水平不同的苦瓜为材料，探讨了适用于苦瓜苗期人工接种枯萎病菌的抗性鉴定方法；以此为基础，对来自国内外的43 份苦瓜种质资源进行了抗源筛选，以其中的抗病亲本‘0417’和感病亲本‘472113’为材料，研究了苦瓜对枯萎病抗性的遗传规律。结果表明，直接水培接种法是较适合于苦瓜苗期枯萎病抗性鉴定的方法，适宜的接种菌液孢子浓度为4 × 106 · mL-1。在苦瓜种质资源中，枯萎病抗源普遍存在，尤以野生种或半栽培种抗病性较强。苦瓜枯萎病抗性受单一显性核基因控制，其广义遗传力为90.78%。

The rhizosphere is the interface between plant roots and soil where interactions among a myriad of microorganisms and invertebrates affect biogeochemical cycling, plant growth and tolerance to biotic and abiotic stress. The rhizosphere is intriguingly complex and dynamic, and understanding its ecology and evolution is key to enhancing plant productivity and ecosystem functioning. Novel insights into key factors and evolutionary processes shaping the rhizosphere microbiome will greatly benefit from integrating reductionist and systems-based approaches in both agricultural and natural ecosystems. Here, we discuss recent developments in rhizosphere research in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.

以青枯病和黑胫病不同抗性烤烟品种‘红花大金元’、‘云烟-87’和‘K326’为材料(对青枯病和黑胫病的抗性均表现为K326>云烟87>红大),在石林和寻甸两个不同生态区进行田间试验,采用平板稀释计数法和Biolog技术研究不同抗性品种不同生育期根际微生物群落动态及功能多样性的差异.结果表明: 烤烟根际土壤细菌、放线菌和微生物总量与品种抗性均呈正相关,而真菌数量与品种抗性呈负相关;两地移栽后35、55和75 d均有一致规律.不同品种根际微生物对6类碳源的利用和碳源利用率(AWCD)存在一定差异,其中寻甸点移栽后55和75 d抗病烤烟品种对糖类、氨基酸类、羧酸类、多聚物类和胺类的利用程度比感病品种高,而移栽后75 d对酚酸类的利用刚好相反;移栽后55和75 d抗病品种的AWCD值显著大于感病品种.而石林点移栽后35、55和75 d根际微生物对6类碳源的利用能力和AWCD值虽与品种抗性无明显相关关系,但3个品种之间有显著差异.主成分分析表明,两地不同品种根际微生物碳源利用特征均存在差异,且在PC1和PC2上有较好的体现,以移栽后55和75 d差异最显著.表明不同抗性品种间根际微生物的群落结构和功能多样性存在差异,且同一品种因栽培环境的不同，其根际微生物的群落结构和功能多样性也有所变化.

Autotrophic ammonia oxidation occurs in acid soils, even though laboratory cultures of isolated ammonia oxidizing bacteria fail to grow below neutral pH. To investigate whether archaea possessing ammonia monooxygenase genes were responsible for autotrophic nitrification in acid soils, the community structure and phylogeny of ammonia oxidizing bacteria and archaea were determined across a soil pH gradient (4.9-7.5) by amplifying 16S rRNA and amoA genes followed by denaturing gradient gel electrophoresis (DGGE) and sequence analysis. The structure of both communities changed with soil pH, with distinct populations in acid and neutral soils. Phylogenetic reconstructions of crenarchaeal 16S rRNA and amoA genes confirmed selection of distinct lineages within the pH gradient and high similarity in phylogenies indicated a high level of congruence between 16S rRNA and amoA genes. The abundance of archaeal and bacterial amoA gene copies and mRNA transcripts contrasted across the pH gradient. Archaeal amoA gene and transcript abundance decreased with increasing soil pH, while bacterial amoA gene abundance was generally lower and transcripts increased with increasing pH. Short-term activity was investigated by DGGE analysis of gene transcripts in microcosms containing acidic or neutral soil or mixed soil with pH readjusted to that of native soils. Although mixed soil microcosms contained identical archaeal ammonia oxidizer communities, those adapted to acidic or neutral pH ranges showed greater relative activity at their native soil pH. Findings indicate that different bacterial and archaeal ammonia oxidizer phylotypes are selected in soils of different pH and that these differences in community structure and abundances are reflected in different contributions to ammonia oxidizer activity. They also suggest that both groups of ammonia oxidizers have distinct physiological characteristics and ecological niches, with consequences for nitrification in acid soils.