不同果肉厚度辣椒内生微生物群落差异及其与果肉厚度的关联

Variations in endophytic microbial communities and their association with pulp thickness in pepper varieties with different pulp thickness

摘要:

目的 探究不同果肉厚度辣椒4个生态位的内生微生物群落差异及关联，挖掘不同辣椒果肉厚度对应的微生物群落差异。方法 以不同果肉厚度的辣椒为试验材料，分别提取辣椒根、茎、叶、果部位的DNA，利用Illumina平台对不同果肉厚度辣椒的4个生态位内生微生物群落进行细菌16S rRNA基因和真菌ITS区测序，鉴定并筛选与辣椒果实厚度具有潜在关联的菌群，同时开展盆栽试验进行验证。结果 不同果肉厚度辣椒的4个生态位的内生细菌和真菌群落均存在差异，其中果部细菌群落结构差异最为显著。果实属水平柱状图和物种差异分析表明，鞘氨醇单胞菌属(Sphingomonas)在厚肉型辣椒中显著富集，且与果肉厚度呈正相关。从辣椒果实中分离出28种内生菌，其中有2株菌属于鞘氨醇单胞菌属，分别为水生鞘氨醇单胞菌(Sphingomonas aquatilis)和菽内氏鞘氨醇单胞菌(Sphingomonas yabuuchiae)，这2株菌均具备产吲哚-3-乙酸(indole-3-acetic acid, IAA)和固氮能力。通过辣椒盆栽试验发现，这2株内生菌可显著促进辣椒果实生长，施加菌剂的辣椒果肉厚度增加75.44%。结论 辣椒果实中鞘氨醇单胞菌属的相对丰度与辣椒果肉厚度呈显著正相关，且该菌属能促进辣椒果实生长。本研究对揭示内生微生物群落在调控辣椒果实发育响应中的作用具有重要意义，可为辣椒果实品质改良提供必要的理论依据。

Abstract:

Objective To investigate the differences and associations in endophytic microbial communities across four ecological niches of pepper varieties with varying pulp thickness and to delve into the microbial community disparities associated with different pepper pulp thickness.Methods We extracted DNA from the roots, stems, leaves, and fruits of pepper varieties with varying pulp thickness. The bacterial 16S rRNA gene and fungal ITS region of the endophytic microbial communities within these four niches were sequenced on the Illumina platform. Microbial taxa potentially associated with pulp thickness were identified and screened, followed by validation through pot experiments.Results Endophytic bacterial and fungal communities in the four ecological niches of pepper varieties with different pulp thicknesses all exhibited differences. Particularly, the bacterial community structure in the fruit displayed the most significant variations. Bar plots at the genus level and analyses of species disparities revealed that the genus Sphingomonas was significantly enriched in the pepper varieties with thick pulp and showed a positive correlation with pulp thickness. A total of 28 endophytic strains were isolated from pepper fruits. Among them, two strains belonged to the genus Sphingomonas, identified as S. aquatilis and S. yabuuchiae. Each of the two bacterial strains exhibited capabilities of both indole-3-acetic acid production and nitrogen fixation. Pot experiments demonstrated that inoculation with the two endophytic strains significantly promoted the fruit growth of pepper plants, increasing the pulp thickness by 75.44%.Conclusion The relative abundance of Sphingomonas in pepper fruits showed a significantly positive correlation with pulp thickness and Sphingomonas promoted fruit growth. This study is of great significance for revealing the role of endophytic microbial communities in the regulation of pepper fruit development and lays a theoretical foundation for improving pepper fruit quality.