The Proteomics Research On Bacillus Subtilis Strain OKB105Interacted With Rice

Bacillus subtilis is an important kind of plant growth-promoting rhizobacteria (PGPR). It is widely used as a biological pesticide and fertilizer. It can promote plant growth and control diseases through producing plant hormones, volatile compounds and improving the availability of plant nutrients. Our lab has shown that Bacillus subtilis strain OKB105can significantly increase the height and fresh weight of mode plant tobacco previously.The analysis on the whole genome of OKB105strain indicates that it does not contain synthetic gene cluster of IAA, cytokinin and gibberellin and also the volatile compounds. The promotion of biomass is different from before. The purpose of this study is to establish the interaction system between OKB105strain and rice and then reveal the growth-promoting mechanism through using2-DE.In this study, the rice seeds and seedlings were treated by the suspension of strain OKB105with different concentration (105、106、107cfu·ml-1). We measured the rice plant height and the root length after one week. The results showed that:when it reached to106cfu·ml-1, it can obviously promote the rice plant height. The promoting percentage was more than25.2%compared with the control. The concentration of105cfu·ml-1had no significant effect on rice plant height and the root length. However, the concentration of107cfu·ml-1would inhibit the growth of rice. This shows that only appropriate Bacillus concentration can promote the growth of rice. On this basis, we select interaction between strain OKB105and rice and then studied the promoting mechanism using two dimensional electrophoresis technology.The success of two-dimensional electrophoresis technology is to establish an effective, repeatable method of sample preparation and appropriate two-dimensional electrophoresis conditions. This article used interaction system between rice and strain OKB105, optimizing the extraction method of the total protein and the two-dimensional electrophoresis conditions about total protein of the strain OKB105. The results showed that concentration of separating gel10%, maximum voltage8000V, focus60000Vh, then increasing the step of low voltage and slow desalination could improve the quality of the picture. It will lay a good foundation for studying the interaction between rice and Bacillus subtilis on proteomic level.In this study, we used the previously optimized methods and conditions for rice and strain OKB105interaction, then extracted the total protein and carried on two-dimensional electrophoresis. Experimental results showed that there were a total of15differentially expressed protein spots compared with control. Among these protein spots,13protein spots were up-regulated expression and2protein spots were down-regulated expression. Finally, we dug differentially expressed protein spots and identified by mass spectrometry (MS), analysising their functions through PD-Quest software. The results showed that there were12kinds of functional protein spots. They play important roles in protein secretion, quorum sensing system, signal transduction, outer protein formation, cell division, activation of gene transcription, energy metabolism. In-depth study of these identified proteins will help a better understanding of the promoting mechanisms of the Bacillus subtilis.