β-氨基丁酸诱导辣椒抗病机理的研究

Studies of Disease-Resistance Mechanism of Pepper Induced by β-Aminonbutyric Acid

以CV98,茄门和931等品种为供试材料,对β-氨基丁酸诱导辣椒后叶片中β-1,3-葡聚糖酶、几丁质酶和过氧化物酶活性动态变化进行测定.结果表明,β-氨基丁酸对不同抗、感辣(甜)椒β-1,3-葡聚糖酶活性、几丁质酶活性和过氧化物酶活性有不同程度的提高,但辣椒品种酶活性升高的幅度高于甜椒品种,且这3种PR蛋白活性变化与诱抗效果的表现相一致.β-氨基丁酸可以诱导几丁质酶ClassⅢ和脂氧合酶基因的表达,诱导处理辣椒后,几丁质酶ClassⅢ和脂氧合酶基因的表达都呈现低-高-低的抛物线型发展趋势,6 h时表达量较小或不表达,大多在12～24 h表达量达最大,之后表达开始减弱,到48 h基本停止表达或微弱表达.对所得差异片段进行核苷酸序列同源性分析,发现与已经报道的辣椒脂氧合酶的编码序列高度同源,达100%.

Treatment of three pepper cultivars, ＂CV98＂, ＂Qiemen＂ and ＂931＂ , with β-aminobutyric acid （BABA） induced resistance to subsequent infection by Phytophthora infestans. BABA treatment induced the synthesis and accumulation of pathogenesis-related proteins in the intercellular fluids of pepper plants 3 d after induction. The quantities and changes of these PR proteins had no differences among pepper cultivars with different resistance. The results of enzymic assays showed that activities of β-1,3-glucanases, chitinases and POD all improved after BABA treatment, but the activities of these three heightened more in hot peppers than in sweat peppers. Chitinase Class Ⅲ and lipoxygenase could been induced by BABA. It is shown that The expression of the genes varied like parabola-shaped during the 48 h. The genes are started to express at 6 h and reached a peak at 12-24 h after treatment with the inducers, then the expressions are weakened. Nucleotide sequence analysis of the differential cDNA fragment shows that its nucleotide sequence is highly homologous with the nucleotide sequence encoded lipoxygenase of capsicum.