College of Plant Protection, Southwest University, Chongqing 400715, China.
Citrus Research Institute, Southwest University, Chongqing 400712, China.
Funct Plant Biol. 2019 Jun;46(6):543-554. doi: 10.1071/FP18243.
NADPH oxidases, encoded by rbohs (respiratory burst oxidase homologues), transfer electrons from NADPH to molecular oxygen (O2) to generate superoxide anion (O2•-), which is the first step in the formation of hydrogen peroxide (H2O2) in the plant-pathogen interaction system. In the present work, six citrus rbohs (Csrbohs) genes were identified in citrus, and their possible involvement in resistance to Xanthomonas citri ssp. citri (Xcc) was examined. Inoculation with Xcc promoted the H2O2 production and induced expression of the Csrbohs, especially CsrbohD. Results showed that CsrbohD was markedly induced in the resistant genotype kumquat 'Luofu' [Fortunella margarita (Lour.) Swingle] compared with grapefruit 'Duncan' [Citrus paradisi (Linn.) Macf.]. Virus-induced gene silencing (VIGS) of CsrbohD resulted in reduced resistance to Xcc in grapefruit, but not in kumquat. Compared with non-silenced plants, canker-like symptoms were observed earlier, and they were more extensive in the CsrbohD-silenced grapefruit. Silencing of CsrbohD also suppressed the Xcc induced reactive oxygen species (ROS) burst, and resulted in accumulation of more Xcc bacterial colonies. Taken together, these data indicate that CsrbohD promotes resistance to Xcc, especially in grapefruit.
NADPH 氧化酶，由 rbohs（呼吸爆发氧化酶同源物）编码，将电子从 NADPH 转移到分子氧（O2）以生成超氧阴离子（O2•-），这是植物-病原体相互作用系统中过氧化氢（H2O2）形成的第一步。在本工作中，在柑橘中鉴定了六个柑橘 rbohs（Csrbohs）基因，并研究了它们可能参与对柑橘溃疡病菌（Xanthomonas citri ssp. citri，Xcc）的抗性。Xcc 的接种促进了 H2O2 的产生，并诱导了 Csrbohs 的表达，特别是 CsrbohD。结果表明，与葡萄柚‘邓肯’[Citrus paradisi（Linn.）Macf.]相比，抗性基因型金桔‘芦柑’[Fortunella margarita（Lour.）Swingle]中 CsrbohD 明显诱导。柑橘 CsrbohD 的病毒诱导基因沉默（VIGS）导致葡萄柚对 Xcc 的抗性降低，但在金桔中则没有。与非沉默植物相比，CsrbohD 沉默的葡萄柚更早出现溃疡样症状，且症状更广泛。CsrbohD 的沉默还抑制了 Xcc 诱导的活性氧（ROS）爆发，并导致更多 Xcc 细菌菌落的积累。综上所述，这些数据表明 CsrbohD 促进了对 Xcc 的抗性，特别是在葡萄柚中。
