6 个不同品种荔枝果肉内生细菌群落多样性的高通量测序分析

【目的】内生菌在植物生长发育中发挥重要作用，分析不同品种荔枝果肉内生细菌群落结构及多样性，挖掘和利用潜在荔枝内生菌种资源，为进一步研究荔枝与内生菌互作关系提供参考依据。【方法】以 6 个不同品种荔枝的果肉组织为材料，PCR 扩增 16S rDNA 的 V3~V4 区，利用 MiSeq 高通量测序技术分析果肉组织内生细菌在门、科、属和种分类水平上的群落组成及优势菌群，结合 Alpha 多样性分析评估内生细菌群落多样性。【结果】对 6 个品种荔枝果肉内生细菌 16S rDNA 的 V3~V4 区进行扩增，共获得 2 139 086 条序列，其平均长度为 376 bp。不同品种荔枝果肉内生细菌群落在相对丰度和多样性上无显著差异。在门分类水平，变形菌门为主要优势细菌门类，其次为放线菌门。在科、属和种分类水平上，不同品种荔枝内生菌群落结构相似，但相对丰度占比不同。差异菌群分析结果显示，假单胞菌属（Pseudomonas）、果胶杆菌属（Pectobacterium）、苍白杆菌属（Ochrobactrum）和迪基氏菌属（Dickeya) 在优良品种‘鹅蛋荔’‘糯米糍’和‘观音绿’中显著富集，根瘤菌属（Bradyrhizobium）和变形菌属（Snodgrassella）只在‘鹅蛋荔’中富集。根据菌群相对丰度进行聚类分析，‘观音绿’‘糯米糍’和‘鹅蛋荔’的相似性更高。Alpha 多样性分析结果表明，6 种荔枝果肉内生菌群仅在丰度和多样性上存在差异，但未达到显著水平。【结论】该研究首次分析了 6 个不同品种荔枝果肉内生细菌的群落结构，并在优良荔枝品种中发现特有的微生物类群富集现象，可为后续提升荔枝品质、开发利用内生菌提供理论依据和重要参考。

Endophytic Bacterial Community Diversity in Pulp of Different Litchi Varieties Based on High-throughput Sequencing Analysis

【Objective】Endophytic bacteria exert an important role in plant growth and development. The study aims to analyze the community structure and diversity of endophytic bacteria in pulp of different litchi varieties, and screen and utilize the potential endophytic bacteria resources, which would provide references for further research on the interaction between litchi and endophytic bacteria.【Method】The pulp tissues of 6 different litchi varieties were used as materials. MiSeq high-throughput sequencing technology was used to compare and analyze the community composition and dominant flora of endophytic bacteria at phylum, family, genus and species classification levels in pulp tissues after the V3~V4 region of 16S rDNA was amplified by PCR. The diversity of endophytic bacteria was evaluated combined with Alpha diversity analysis.【Result】A total of 2 139 086 sequences of endophytic bacteria 16S rDNA were obtained in the V3~V4 region of 6 litchi varieties, and the average length of amplified sequences was 376 bp. There was no significant difference in the abundance and diversity of endophytic bacteria in different litchi varieties. At the phylum classification level, Proteobacteria was the main dominant bacterial group in litchi pulp tissue, followed by Actinomyces. At the levels of family, genus and species classification, the endophytic bacterial community structure of different litchi varieties was similar, but the bacterial abundance proportion was different. Differential bacterial community analysis showed that the Pseudomonas, Pectobacterium, Ochrobactrum and Dickeya were significantly enriched in the high-quality varieties of ‘Edanli’, ‘Nuomici’ and ‘Guanyinlv’. In addition, Bradyrhizobium and Snodgrassella were only enriched in the ‘Edanli’. The clustering analysis of relative abundance of bacteria showed that ‘Guanyinlv’, ‘Nuomici’ and ‘Edanli’, had higher similarity. Alpha diversity analysis showed that there were differences in the abundance and diversity of endophytic flora in pulps of 6 litchi varieties, but the differences were not significant.【Conclusion】In this study, the community structure of endophytic bacteria in the pulp of six different litchi varieties was analyzed, and some unique microbial genera were enriched in the high-quality litchi varieties. The results could provide a theoretical basis and important references for the development and utilization of endophytic bacteria to improve litchi quality.