Role Of Hormones In The Interaction Between Rice And Pathogen & Functional Analysis Of Defense-responsive Gene OsDR10

Rice is one of the most important food crops in the world,hold an unshakable status in agricultural production.Disease is an important factor which leads to yield reduction and quality losses of rice.Traditional methods such as applying pesticide against disease has become increasingly unable to meet the demand of rice production in China.Therefore,it is of great significance and broad application prospects to find and develop new disease resistant germplasm resources and to cultivate more and more excellent varieties of rice.This study started with the important regulator of plant disease resistance reactions,hormones,and aimed at a more comprehensive understanding of the physiological and biochemical process of rice and pathogen interaction,in order to get better disease resistance ways and find more excellent resistant resources.In addition,functional analysis and identification of defense-responsive gene OsDR10,which is a negative regulator of disease resistance,may help us to better understand this gene,and to lay the foundation for rational and effective use of the gene resources.We used exogenous hormones to treat rice,to detect the specific changes in the expression of OsGH3 gene family members,which are responsive to auxin in the very early stage,and to understand the response of these genes to hormones.In addition,we also examined the expression of two OsGH3 genes,in rice disease resistance materials and susceptible materials after inoculation with Xanthomonas oryzae pv.Oryzae(Xoo).Results show that OsGH3.4 and OsGH3.5 may be involved in the positive regulation of rice bacterial blight resistance.OsGH3.9,one member of OsGH3 family,were constructed over-express and suppress vectors.We use the method of agrobacterium mediated genetic transformation to transform the two vectors into the middle susceptible disease rice materials Zhonghua 11.Through OsGH3.9 expression in the plants was detected that we do get the over-expressed and suppressed transgenic plants.But the results of Xoo inoculations to the transgenic plants,compared with wild type Zhonghua 11,were not associated with the expression of OsGH3.9.We used liquid culture medium to culture the pathogens of rice bacterial leaf blight and bacterial streak disease,then extracted hormones from the culture supernatant of hormone at mid-stationary phase and detected.The results showed that these pathogens are able to secrete auxin,jasmonic acid,abscisic acid.The addition of L-Trp to the culture medium could improve the auxin content in the supernatant of PXO99 culture medium,which indicated that the strain could synthesize auxin through Trp-dependent indole-3-acetic acid biosynthesis pathway.We have a more intuitive understanding of the expression pattern of OsDR10 by using ?-glucuronidase reporter gene linked to the OsDR10 promoter that transformed into Zhonghua 11,as well as the immunohistochemistry analysis.OsDR10 is a highly expressed gene in seed development,germination and callus.The experimental results show that the seeds of OsDR10-suppressed plants are more difficult to break the dormancy and normally germinate than the wild type.By screening Minghui 63 cDNA yeast double hybrid library,we find that OsDR10 may involve in defense responses by interacting with the allele of xa5,which is a disease resistant gene of bacterial leaf blight.