两种黄单胞病菌诱导水稻一氧化氮产生和防卫基因表达的比较研究

 【目的】阐明在不同黄单胞病菌诱导的水稻过敏性细胞死亡(HCD)中的一氧化氮(NO)信号途径及其作用机制。【方法】比较分析了在水稻细胞－番茄斑点病菌(Xanthomonas campestris pv. vesicatoria, Xcv)不亲和互作、水稻－白叶枯病菌(X. oryzae pv. oryzae, Xoo)亲和互作中NO的发生以及NO对水稻防卫基因诱导表达的影响。【结果】Xcv不仅诱导了NO的迸发、NOS活性及其NO合成相关基因(nos和nr)的表达，而且诱导了防卫基因(苯丙氨酸解氨酶基因pal、过氧化物酶基因pox和谷胱苷肽转硫酶基因gst)的表达；Xoo不诱导NO的迸发，抑制了NOS的活性、NO合成相关基因和防卫基因的表达；NO清除剂PTIO和Xoo显著地抑制了Xcv 对防卫基因表达的诱导作用。【结论】Xcv通过NO信号途径诱导了水稻防卫基因的表达和HCD；Xoo 通过NO抑制或解毒机制抑制了由NO介导的防卫基因的表达及其HCD的发生。

Comparative Analysis of Nitric Oxide Generation and Induction of Defense Gene Expression by Xanthomonas campestris pv. vesicatoria and X. oryzae pv. oryzae of Rice Suspension-Cultured Cells

Abstract：【Objective】To elucidate a key role for nitric oxide (NO) played during rice-Xanthomonas spp interactions by triggering hypersensitive cell death (HCD) and inducing defense genes.【Method】NO production and defense gene expression in rice suspension-cultured cells was compared after inoculations with X. campestris pv. vesicatoria (Xcv), a non-host bacterial pathogen and X. oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice. 【Result】NO burst, activation of nitric oxide synthase (NOS), expression of NO synthesis-related genes (nos and nr) and defense-related genes (pal, pox and gst) was found to be significantly induced by Xcv, not by Xoo. Application of NO scavenger PTIO or co-inoculation of Xcv with Xoo resulted in the significant suppression of Xcv-induced gene expression.【Conclusion】Xcv induces defense gene expression and HCD of rice suspension cultures through a NO-dependent signal pathway, whereas Xoo inhibits NO-mediated defense gene expression and HCD by suppressing NO production and detoxifying NO.