Kim Young-Cheol, Kim Soo-Yong, Paek Kyung-Hee, Choi Doil, Park Jeong Mee
Plant Genome Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333, Republic of Korea.
Biochem Biophys Res Commun. 2006 Jun 30;345(2):638-45. doi: 10.1016/j.bbrc.2006.04.124. Epub 2006 May 2.
A putative cytochrome P450 gene from chili pepper, Capsicum annuum L. Bukang cytochrome P450 (CaCYP1), was identified using cDNA microarray analysis of gene expression following induction of the leaf hypersensitive response by inoculation of pepper plants with the non-host pathogen Xanthomonas axonopodis pv. glycines 8ra. The full-length cDNA of CaCYP1 encoded a protein of 514 amino acid residues, which contained a putative hydrophobic membrane anchoring domain in the N-terminal region, and a heme-binding motif in the C-terminal region. Analysis of the deduced amino acid sequence of CaCYP1 revealed that it has high homology to Arabidopsis CYP89A5, the function of which is unknown. Expression of CaCYP1 was preferentially increased in pepper plants in response to non-host pathogen inoculation and also during the host resistance response. CaCYP1 expression also increased following treatment with salicylic acid and abscisic acid, while treatment with ethylene had a mild effect. Using a virus-induced gene silencing-based reverse genetics approach, we demonstrated that suppression of CaCYP1 results in enhanced susceptibility to bacterial pathogens. Interestingly, gene silencing of CaCYP1 in pepper plants resulted in the reduced expression of the defense-related genes CaLTP1, CaSIG4, and Cadhn. Our results indicated that CaCYP1, a novel cytochrome P450 in pepper plants, may play a role in plant defense response pathways that involve salicylic acid and abscisic acid signaling pathways.
通过用非寄主病原菌大豆细菌性斑点病菌8ra接种辣椒植株诱导叶片过敏反应后，利用基因表达的cDNA微阵列分析，从辣椒（Capsicum annuum L.）中鉴定出一个假定的细胞色素P450基因——布康细胞色素P450（CaCYP1）。CaCYP1的全长cDNA编码一个由514个氨基酸残基组成的蛋白质，该蛋白质在N端区域含有一个假定的疏水膜锚定结构域，在C端区域含有一个血红素结合基序。对CaCYP1推导的氨基酸序列分析表明，它与功能未知的拟南芥CYP89A5具有高度同源性。CaCYP1的表达在辣椒植株中因非寄主病原菌接种而优先增加，在寄主抗性反应过程中也增加。用水杨酸和脱落酸处理后，CaCYP1的表达也增加，而用乙烯处理的影响较小。利用基于病毒诱导基因沉默的反向遗传学方法，我们证明抑制CaCYP1会导致对细菌病原体的易感性增强。有趣的是，辣椒植株中CaCYP1的基因沉默导致防御相关基因CaLTP1、CaSIG4和Cadhn的表达降低。我们的结果表明，CaCYP1是辣椒植株中的一种新型细胞色素P450，可能在涉及水杨酸和脱落酸信号通路的植物防御反应途径中发挥作用。
