Colonization In Wheat And Enhance Seeding Drought Resistance By Azorhizobium Caul1nodans ORS571

In china,52.5%of the land is the arid and semi-arid area. If the drought occurredin wheat seedling stage, it will hinder the normal growth of wheat. Studies showedthat, rhizobium can live independently and has symbiotic nitrogen-fixing withleguminous, it as endogenous bacterium interacts with leguminous plant.Azorhizobium caulinodans ORS571(A.caulinodans) is a kind of plant endogenousnitrogen-fixing bacteria, it not only has a certain nitrogen-fixing ability and canpromote the growth of the host or non-host plant, but it has the enhancement theability against adversity stress and pathogen infect in the plants.1. This study established infection system of the A.caulinodans on wheatseedling. First of all, in the gnotobiotic conditions, we compared infection efficiencyof five different infection methods, to established infection system of theA.caulinodans on wheat seedling in the gnotobiotic conditions; at the same time, wedid foliar spray with A. caulinodans in the greenhouse. We explored A.caulinodans oneffect of the wheat growth as the promoting function of foliar fertilization. Finally,this study established infection system of the A.caulinodans on wheat seedling.2. In the gnotobiotic conditions, using the gfp-A.caulinodans infect respectivelyXiaoyan22seeds, roots and leaves, we got detection using fluorescence microscopeand laser confocal microscope after free-hand section and mounting technique. Theresults showed that A.caulinodans can through the root hair and lateral root fractureinto the roots and the vascular tissue, then colonized in vascular tissue and cell gapshall. At the same time, the gfp-A.caulinodans colonized in wheat root can move up tothe wheat leaf, the gfp-A.caulinodans colonized in wheat leaf can move from thestomata to leaf insid. These results will provide the theory basis for the molecule level research of bacteria-plant interaction.3. This research use A.caulinodans infect wheat seeds, extracting total RNA ofthe24h Treatment (TsR24) and control (CsR24), then small RNA sequencing basedon the second generation high-throughput sequencing technology. Sequencing resultsshowed that miRNA related to the adversity stress accounted for12%of all miRNA.Expression of14miRNA related to drought were up-regulated,7miRNA weresignificantly down-regulated. In the up-regulated miRNA, miR1867, miR854reacheda significant difference. In the down-regulated miRNA, miR1088, miR1126reached asignificant difference. The results provide new ideas for research of rhizobiuminteracting with drought wheat.4. This study screened wheat xiaoyan22as drought sensitive variety toA.caulinodans. We determinated the A.caulinodans growth curve in drought stress,results showed that A.caulinodans can reproduce in drought stress. In the openingcondition, we infected drought stress xiaoyan22seeds with A.caulinodans, the resultsshowed that seed germination potential was improved, germination index wasincreased. We infected drought stress xiaoyan22laminas with A.caulinodans, theresults showed that leaf soluble protein, relative water content and proline contentwere increased significantly. A.caulinodans has buffered, regulated and promotedfunction of the seeds germination on xiaoyan22and contribute to drought-relief ofwheat seeding.Based on these studies showed that A.caulinodans can systemic distribute in thewheat seedlings and promote seedling growth. We found expression differencessignificant miRNA related to drought after24h turough seed infection withA.caulinodans. A.caulinodans can improve the wheat seedling drought resistance onlevel of physiological and biochemical. This Study provides a new idea for wheatdrought resistance research.