The Community Structures Of Bacterial Endophytes Inside Different Genotypes Of Rices And Preliminary Exploration On Their Transmission Route

Decades of research have demonstrated the importance of microorganisms for plant health.Deciphering the interaction between plants and their microbiomes is a hot topic all over the world.With the deepening of research of plant endophytes,it was found that there are rich microbial resources inside plant,and most of them have some beneficial functions,such as promoting growth and degradation of organic pollutants,etc.,which has good prospects in the agricultural production.Most of relevant researches used traditionally culture-dependent methods or low-throughput culture-independent approaches.Nowadays high-throughput sequencing technique has been gradually applied in the field of plant endophytes.Compared to rhizospheric and phyllospheric microganism,seeds served as the reproductive organs of plants,of which the related microbes research is still week,especially the research of bacterial endophytes in plant seeds.In this study,8 different genotypes of rice were selected to investigate the SSR molecular fingerprinting and phenotypic traits,and endophytic bacterial communities in tested rice seeds were investigated using Illumina high-throughput sequencing technique to sequence the 16 S rRNA gene,which aimed to further reveal the correlation between rice genotypes and its endophytic bacterial flora,and to preliminary definite the core bacterial endophytes flora in rice seeds.On the other hand,3genotypes of rice were selected to investigate the bacterial endophytes in parental seeds,roots,stems and filial seeds using Illumina high-throughput sequencing technique,and to explore the possibility for vertical transmission of endophytes in rice.The results showed as follows:1.The variation range of genetic similarity for eight different rice genotypes was 0.66-0.95;the SSR molecular fingerprinting of 8 genotypes of rice could echo with the phenotypic traits,but cannot correspond to the hierarchical clustering of community structure of endophytic bacteria in rice seeds.It indicated that the composition of endophytic bacteria in rice seeds was irrelevant with the genetic relationship of the rice genotypes;2.High-throughput sequencing contributes to gaining more insight into rich endophytic bacteria in rice seeds.There were four dominant phyla,Proteobacteria,Firmicutes,Bacteroidetes and Actinobacteria,in rice seeds.Meanwhile some infrequent phyla,such as Acidobacteria,Fusobacteria,Chlamydiae and Gemmatimonadetes,were first detected in tested seeds;3.The analysis of shared bacterial endophytes in seeds of different rice genotypes showed that Pantoea(26.69%-72.77%,average=48.92%),Acinetobacter(0.16%-34.23%,average=14.36%)and Xanthomonas(3.20%-22.19%,average=11.55%)served as dominant genera coexisted in all tested rice seeds,but with obviously different proportions;4.The endophytic bacterial communities were obviously different in parental seeds,roots,stems and filial seeds of rice,but there still existed the shared endophytic genera among these tissues.The endophytic bacterial communities in rice tissues among 3 genotypes differ slightly,but with evidently different abundance of those dominant genera.And there existed the shared endophytes OTUs andgenera in rice tissues among different genotypes.It was preliminarily speculated that endophytes in rice seeds are most likely to transmit to the next generation via seeds.