RESULTS: In this study, the composition and diversity of the Vanilla rhizosphere bacterial community were explored by analyzing rhizosphere soil and root tissue samples as well as green pods of three accessions of Vanilla planifolia grown on different types of substrates (compost and leaf litter). In addition, the endophytic bacterial diversity of roots and green pods as well as the evolution of endophytic bacteria after the curing process of vanilla green pods were analyzed based on a metabarcoding approach. The results showed that bacterial species richness and diversity were higher in the compost. The analysis of the soil bacterial composition displayed that Halomonas, Pseudoalteromonas, Enterobacter and Bradyrhizobium were the most abundant genera. Moreover, the results indicated that the soil bacterial community structure was linked to the host plant genotype. Regarding the roots endophytic bacteria composition, the genera Halomonas, Pseudoalteromonas, Bacillus and Carboxydocella genera were present in all samples, independently from the substrate nature. Several genera including Bacillus, Bradyrhizobium, Burkholderia and Halomonas were transmitted internally from the roots to the green pods. The curing process reduced the bacterial richness and bacterial diversity associated with the green pods. Halomonas, Pseudoalteromonas, Bacillus, and Carboxydocella are the dominant genera in the pods after the curing process.
CONCLUSIONS: This study provides an overview of changes of the bacterial communities dynamics especially endophytic in the roots and the green pods. It highlighted bacterial genera (Halomonas, Pseudoalteromonas, Bacillus, and Carboxydocella) potentially implicated in the formation of aroma compounds of vanilla beans.
结果:在这项研究中,通过分析根际土壤和根组织样品以及在不同类型的基质(堆肥和落叶)上生长的三种香草草的绿色豆荚,探索了香草根际细菌群落的组成和多样性。此外,基于元编码方法分析了香草绿豆荚根和绿豆荚内生细菌的多样性以及腌制后内生细菌的进化。结果表明,堆肥中细菌物种丰富度和多样性较高。对土壤细菌组成的分析表明,假交替单胞菌,肠杆菌和缓生根瘤菌是最丰富的属。此外,结果表明,土壤细菌群落结构与寄主植物基因型有关。关于根系内生细菌的组成,盐单胞菌属,假交替单胞菌,所有样本中都存在芽孢杆菌和羧化杆菌属,独立于底物的性质。几个属,包括芽孢杆菌,缓生根瘤菌,伯克霍尔德菌和Halomonas从根部内部传播到绿色豆荚。固化过程降低了与绿色豆荚相关的细菌丰富度和细菌多样性。Halomonas,假交替单胞菌,芽孢杆菌,和羧基菌是腌制后豆荚中的优势属。
结论:本研究提供了根和绿色豆荚中细菌群落动态尤其是内生植物的变化的概述。它突出了细菌属(Halomonas,假交替单胞菌,芽孢杆菌,和羧基菌)可能与香草豆香气化合物的形成有关。