| Pea(Pisum sativum L.)is a rosaceae butterfly plant,it is nutritionally comprehensive and widely planted.Endophytic bacteria plays a very important role in the whole growth cycle of pea,so the research on endophytic bacteria in pea attach more and more attention.The mature period of plants is an important stage of agricultural production,and the study of endophytic bacteria in this period is helpful to improve the quality and yield of crops.In this study,diversity analysis of endophytic bacteria in 152 samples was obtained by Illumina MiSeq high-throughput sequencing method,and the composition,abundance and diversity of endophytic bacterial community were studied.And longitudinal studies were analysed on the transmission of endophytic bacteria in pea seedling stage,flowering stage and maturity stage.It is helpful for the construction of pea strain resource base and lays a theoretical foundation for further research and application.At the same time,the endophytic bacteria of these samples of mature pea leaves,roots,pod shells and pods were isolated,and their strain morphology was identified.Nitrogen fixation bacteria with nitrogenase activity,phosphorus dissolution,potassium dissolution,indoleacetic acid production,ACC deaminase,cellulase and pectinase promoting growth were screened out.In addition,the nitrogen fixation strains with good plant growth promoting characteristics were applied to the preliminary planting experiment of sweet potato to explore its preliminary influence on the planting and yield of sweet potato.The main findings are as follows:(1)According to the analysis of the microbial diversity of 152 samples of leaf,root,pod shell and pod in mature stage,the four phylum with the highest abundance of these tissues are Proteobacteria,Bacteroides,Firmicutes and Actinomycetes.At the same time,according to the genus level statistics of different tissues,850 genera,890 genera,874 genera and 815 genera were found in leaf,root,pod shell and pod,respectively.Among them,the microbial community diversity of root was the highest,followed by leaf and pod shell,and pod had the lowest microbial diversity.(2)According to the diversity analysis between groups and within groups of different tissues from different kinds of peas in mature stage,it could be obtained that the microbial diversity and community abundance in the same varieties were similar,the microbial diversity and community abundance in different varieties were different,and the microbial diversity and community abundance in different tissues were significantly different.Meanwhile,the abundance of specific strains was different in different tissues of different varieties.(3)From principal component analysis of leaves and roots belonging to seedling,flowering and mature stage,it could be obtained for seedling leaf SL,flowering leaf FL and maturity leaf ML,the communities of most samples have a large overall difference,and the microbial communities of a small number of samples have a certain degree of similarity,which indicated that the bacterial communities in the leaves have a low transitivity and are greatly affected by the external environment.For SR,FR and MR,except for the large difference of endophytic bacterial communities in individual samples,the structure similarity of endophytic bacterial communities in most samples was relatively high and the distribution was relatively uniform,which indicated that the bacterial communities at the roots have a high transitivity.(4)From the mature pea leaves,roots,pod shells and pods,a total of 86 strains of endophytic nitrogen fixing bacteria were obtained and morphological statistics were conducted.Most of the strains were round or subround,pale yellow and white,with neat and opaque edges,raised surface,moist and no special substances.A total of49 endophytic bacteria with nitrogenase activity characteristics were screened,and the strains with high nitrogenase activity capacity were MQK10,MQK44 and MQK52.(5)A total of 51 strains which can dissolve inorganic phosphorus,20 strains which can dissolve organophosphorus,and 8 strains which can dissolve potassium feldspar powder were screened from different tissues of mature peas.Among them,13 endophytic bacteria could simultaneously dissolve inorganic phosphorus and organophosphorus,and 2 endophytic bacteria could simultaneously dissolve inorganic phosphorus,organophosphorus and potassium,which were MQK41 and MQK47.(6)A total of 83 strains that could secrete indoleacetic acid IAA were screened from different tissues of peas in the mature stage,among which MQK07 and MQK10 had a relatively strong ability to secrete IAA with a concentration of more than 3g/mL.Meanwhile,56 strains with the capacity of ACC deaminase were screened.(7)A total of 51 strains with cellulase capacity,22 strains with pectinase capacity were screened from different tissues of mature peas,in addition,20 strains had both cellulase and pectinase abilities.(8)Screening endogenous azotobacter with good properties from mature pea tissues,preparing microbial agents and then applying them to the preliminary experiment of sweet potato planting,it could be obtained that comparing with the control group in sweet potato seedlings without bacteria agent,microbial agents treatment group became more white juice,shorter seedling leaf spacing,larger leaf area.At the same time,sweet potato seedlings in the treatment group maintained these excellent traits during the fast propagation period,and the results showed that the growth quality and yield of sweet potato seedlings were significantly improved after field planting and harvesting.In conclusion,this paper not only focused on the structural characteristics of endophytic bacteria in the mature stage of pea,but also explored the transmission law of endophytic bacteria in different development stages.In this paper,a germplasm bank of endophytic bacteria with growth-promoting properties was established.The excellent growth-promoting bacteria promoted the healthy growth of sweet potato seedlings and increased the yield of sweet potato. |
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