The aim of this work was to gain a more comprehensive and perspicacious view of the endophytic diazotrophic community (EDC) of tomato plant bacteria and assess the effects of chemical fertilization and the plant phenologic stage on the status of those microbes. When the EDC of stem and roots from tomato plants grown in a greenhouse with and without exogenous chemical fertilization was examined by pyrosequencing the nifH gene during the growth cycle, a high taxonomic and phylogenetic diversity was observed. The abundant taxa were related to ubiquitous endophytes such as Rhizobium or Burkholderia but also involved anaerobic members usually restricted to flooded plant tissues, such as Clostridium, Geobacter, and Desulfovibrio. The EDC composition appeared to be dynamic during the growth phase of the tomato, with the structure of the community at the early stages of growth displaying major differences from the late stages. Inorganic fertilization negatively affected the diversity and modified the profile of the predominant components of the EDC in the different growth stages. Populations such as Burkholderia and Geobacter plus the Cyanobacteria appeared particularly affected by fertilization.Our work demonstrates an extensive endophytic diazotrophic diversity, suggesting a high potential for nitrogen fixation. The effect of the phenologic stage and inorganic-chemical soil fertilization on the community structure indicated a dynamic community that responded to environmental changes. These findings contribute to a better understanding of endophytic associations that could be helpful in assisting to shape the endomicrobiome that provides essential benefits to crops.

中文翻译：

---

土壤化学施肥对番茄不同生长阶段内生固氮群落多样性和组成的影响

这项工作的目的是获得对番茄植物细菌内生固氮群落 (EDC) 的更全面和深入的了解，并评估化学施肥和植物物候阶段对这些微生物状态的影响。当通过在生长周期中对 nifH 基因进行焦磷酸测序来检查在温室中生长的番茄植物的茎和根的 EDC 时，无论是否使用外源化学施肥，都观察到了高度的分类学和系统发育多样性。丰富的分类群与无处不在的内生菌有关，如根瘤菌或伯克霍尔德菌，但也涉及通常仅限于淹没植物组织的厌氧成员，如梭状芽孢杆菌、地杆菌和脱硫弧菌。EDC 的组成在番茄的生长阶段似乎是动态的，社区结构在成长的早期阶段与晚期阶段显示出重大差异。无机施肥对多样性产生负面影响，并改变了不同生长阶段 EDC 主要成分的分布。Burkholderia 和 Geobacter 以及蓝藻等种群似乎特别受施肥的影响。我们的工作证明了广泛的内生固氮多样性，表明固氮潜力很大。物候阶段和无机化学施肥对群落结构的影响表明群落是一个响应环境变化的动态群落。