Ectopic expression of the cotton non-symbiotic hemoglobin gene GhHb1 triggers defense responses and increases disease tolerance in Arabidopsis
Ectopic expression of the cotton non-symbiotic hemoglobin gene GhHb1 triggers defense responses and increases disease tolerance in Arabidopsis
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DOI：
10.1093/pcp/pcj076
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发表时间：
2006-08-01
影响因子：
4.9
通讯作者：
Xia, Gui-Xian
中科院分区：
文献类型：
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作者：
Qu, Zhan-Liang;Zhong, Nai-Qin;Xia, Gui-Xian
植物非共生血红蛋白(NsHbs)在多种细胞过程中发挥着重要作用。本实验室以前的证据表明，棉花中一个nsHb类基因(GhHb1)的表达是在黄萎病真菌攻击的棉花根中诱导的。本研究进一步研究了GhHb1基因在棉花植株中的表达模式，并通过该基因在拟南芥中的异位过表达研究了该基因在体内的功能。外源水杨酸、甲基茉莉酸、乙烯、过氧化氢(H_2O_2)和一氧化氮(NO)诱导棉花GhHb1的表达。GhHb1在拟南芥中的异位过量表达导致防御基因PR-1和PDF1.2的结构性表达，从而增强了对紫丁香假单胞菌的抗病能力和对大丽花病菌的耐受性。与野生型对照相比，转GhHb1基因拟南芥幼苗对外源NO的耐受性更强，细胞内NO含量更低。此外，GhHb1基因表达水平相对较高的转基因植株在没有病原体接种的情况下，在叶片上发生了自发的过敏性损伤。我们的结果表明，GhHb1蛋白在抵御病原体入侵的防御反应中发挥作用，可能是通过调节防御过程中的NO水平和H_2O_2/NO的比例。
Plant non-symbiotic hemoglobins (nsHbs) play important roles in a variety of cellular processes. Previous evidence from this laboratory indicates that the expression of a class 1 nsHb gene (GhHb1) from cotton is induced in cotton roots challenged with the Verticillium wilt fungus. The present study examined further the expression patterns of the GhHb1 gene in cotton plants and characterized its in vivo function through ectopic overexpression of the gene in Arahidopsis thaliana. Expression of GhHb1 in cotton plants was induced by exogenously applied salicylic acid, methyl jasmonic acid, ethylene, hydrogen peroxide (H2O2) and nitric oxide (NO). Ectopic overproduction of GhHb1 in Arabidopsis led to constitutive expression of the defense genes PR-1 and PDF1.2, and conferred enhanced disease resistance to Pseudomonas syringae and tolerance to V. dahliae. GhHb1-transgenic Arabidopsis seedlings were more tolerant to exogenous NO and contained lower levels of cellular NO than the wild-type control. Moreover, transgenic plants with relatively high levels of expression of the GhHb1 gene developed spontaneous hypersensitive lesions on the leaves in the absence of pathogen inoculation. Our results indicate that GhHb1 proteins play a role in the defense responses against pathogen invasions, possibly by modulating the NO level and the ratio of H2O2/NO in the defense process.