长期稻-稻-紫云英轮作对水稻种子内生细菌的影响及促生功能评价

Effects of long-term rice-rice-milk vetch rotation on rice seeds endophytic bacteria and evaluation of growth promoting function

种子被视为有益微生物的储存库和载体。与根际和叶际相比,种子相关细菌的研究还十分落后。本研究以长期绿肥植物与水稻轮作(稻-稻-紫云英,R-R-MV)和冬闲(稻-稻-冬闲,R-R-WF)两种种植模式的水稻种子为材料,分离种子内生细菌;在对菌株进行16S r RNA基因系统发育分析基础上,依据分离来源和分类地位选择代表菌株,进行溶磷、产IAA和铁载体等植物促生功能的检测。结果显示,绿肥轮作后水稻种子内生细菌的数量显著高于冬闲,群落组成也发生了明显变化。在属水平上,Pseudomonas和Xanthomonas是R-R-WF中的优势属,分别占28.57%和26.19%,而R-R-MV中Pantoea是优势属,占27.94%,其次是Pseudomonas(14.71%)和Paenibacillus(13.24%)。进行功能检测的31个菌株中,大多数分离株具有有益于植物的特性,表明种子内生细菌与植物的生长及健康密切相关。本研究不仅揭示了长期轮作条件可以改变种子的微生物组成,还获得了有益的微生物资源,将有助于种子内生菌作为生物接种剂在可持续农业中的研究和应用。

Seeds are regarded as a potential reservoir and carrier for beneficial microbes.Compared to rhizosphere and phyllosphere,seed-associated bacteria remain largely unrealized.In this study we investigated the rice seed endophytic bacteria of long term rotations of rice-rice-milk vetch(R-R-MV)and rice-rice-winter fallow(R-R-WF)using cultivationdependent method and functional plate assays,with the aim of assessing the composition,function and the effects of green manure rotation on the rice seed endophytic bacteria.The bacterial population in rice seeds of the R-R-MV rotation was significiant higher than that of R-R-WF.The composition of seed endophytic bacteria was significantly changed after long-term green manure rotation.At genus level,Pseudomonas and Xanthomonas were the largest groups in R-R-WF,accounting for 28.57% and 26.19%.Pantoea was the most dominant genus in R-R-MV,accounting for 27.94%,followed by Pseudomonas(14.71%)and Paenibacillus(13.24%).Most of isolates had plant-beneficial characteristics,indicating their close relationships with plants.The plant beneficial resources obtained in this study will contribute to the research and application of seed endophytes as bioinoculants in sustainable agriculture.