Nitrate reductase-dependent nitric oxide production is required for regulation alternative oxidase pathway involved in the resistance to Cucumber mosaic virus infection in Arabidopsis
2015
Jian, Wei | Zhang, Da-wei | Zhu, Feng | Wang, Shuo-xun | Zhu, Tong | Pu, Xiao-jun | Zheng, Ting | Feng, Hong | Lin, Hong-hui
Nitrate reductase (NR), a key enzyme of nitrogen metabolism, catalyzes the reduction of nitrite to produce nitric oxide (NO). In this study, we investigated the role of NR-dependent NO in alleviating the cucumber mosaic virus (CMV)-caused damage in Arabidopsis thaliana (Arabidopsis). Quantitative real-time polymerase chain reaction analysis indicated that NR genes NIA1 and NIA2 transcripts were significantly increased by CMV infection in Arabidopsis. Further evidence showed that the nia1nia2 mutant and cPTIO-pretreated plants exhibited more serious symptoms (more reactive oxygen species accumulation, higher H₂O₂ content, malonaldehyde content, electrolyte leakage and transcription of CMV coat protein gene) compared with the wild-type (WT) after CMV infection. Analysis of putative molecular mechanism revealed that the expression of genes encoding pathogenesis-related 1 protein, pathogenesis-related 2 protein and alternative oxidase1a protein in nia1nia2 mutant were significantly decreased compared to the WT, and this phenomenon could be reversed by pretreatment with sodium nitroprusside (SNP). However, pretreatment with SNP could not effectively decrease the damage in aox1a mutant caused by CMV. Taken together, our results indicated that the NR-dependent NO was required for regulation the salicylic acid-mediated defense response and cyanide-resistant respiration pathway involved in the resistance to CMV infection, and alternative oxidase pathway played an important role in the defense response mediated by NO.
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