Studies On The Function Of AtSpl11 Gene Regulating The Cell Death And Disease Resistance In Arabidopsis

Plant lesion mimic mutants develop spontaneous cell death syrnptoms in the absence of pathogens attack.Many lesion mimic mutants show enhanced disease resistance to multiple pathogens.AtSpl11 gene(Arabidopsis thaliana Spotted leaf11) is ortholog of rice Spl11 gene which is a negative regulator of plant cell death and disease resistance.Though study on the phenotypes of Atspl11,a T-DNA insertional mutant of AtSpl11,we found it is a lesion mimic mutant that the mutant displays dwarf,spontaneous lesion mimicking hypersensitive response (HR).The experiments of complementation and RNAi confirmed that AtSpl11 was a lesion mimic gene.Moreover,we found AtSpl11 regulated negatively not only cell death but also flowering ahead of time.The results of pathogens inoculation show that AtSpl11 can negatively regulate the plant resistance to some Pseudomonas syringae and Xanthomonas pathogens.And Atspl11 displays enhanced resistance obviously to powdery mildew but more susceptible to Botrytis cinerea. Through test the expression of marker genes in the SA,JA and ethylene(ET) signal pathway,it shows that the content of PR1 is increased largely,however,the content of PDF1.2 is suppressed obviouly.Terefore,it can be concluded that AtSpl11 regulates negatively SA pathway but enhances JA and ET pathway to mediate disease resistance.Many plant U-box preteins possess E3 ubiquitin ligase activity.The analysis of AtSPL11 protein sequence indicates that AtSPL11 contains a U-box domain and six armadillo(ARM) repeats domain.The ubiquitination assay revealed that AtSPL11 possessed E3 ligase activity, and the U-box domain is the key component for the E3 activity.