Functional Study Of Maize Pathogen Resistance Gene NPR1

Maize(Zea mays L.)is an important food crop in China and its production is seriously threatened by diseases.Alteration of the expression of plant disease resistance genes can improve plant disease resistance effectively.NPR1 is a known disease resistance gene that functions in the SA-mediated disease resistance pathway.In this study,At NPR1 was transformed into maize inbred line A188 by Agrobacteriummediated transformation,and the obtained transgenic lines were crossed to the maize inbred line Zheng 58.In addition,the molecular mechanism and the function of Zm NPR1 in participating plant immune response were investigated.We found Zm NPR1 can regulate the expression of the defense-related gene Zm SARD1.The main findings are as follows:1.The At NPR1 was transformed into maize by Agrobacterium-mediated transformation method.A total of 6 independent At NPR1 transformed lines were obtained and further identified by PCR.Two of the six lines only contained the Bar gene.The obtained transgenic T0 plants were crossed to Zheng 58.2.The zmnpr1 mutant was characterized for its disease resistance by inoculation of Rhizoctonia solani at the root of the seedlings.Results showed that the resistance of the mutant plants to Rhizoctonia solani was significantly reduced compared with cosegregation wild-type controls.3.Zm NPR1 up-regulates the expression of Zm SARD1 in the zmnpr1 mutant mesophyll protoplast cells and this effect was independent of SA.There are three TGAbinding elements in Zm SARD1 promoter.Mutation of the TGACG motifs revealed that Zm NPR1 regulates Zm SARD1 through the motif positioned at-312 relative to the start codon.4.The effects of different concentration of SA on Zm NPR1 expression were investigated in maize mesophyll protoplast.The results showed that the Zm NPR1 expression was inhibited by SA.In summary,six fertile transgenic maize A188 plants were obtained.In addition to this,we found that Zm NPR1 plays important roles in plant disease resistance.Our research laid a foundation for further research of maize disease resistance.