【摘要】 利用 PCR方法从水稻黄单胞菌白叶枯致病变种 (Xanthomonas oryzae pv.oryzae,Xoo) Jxo III菌株中克隆到编码诱导植物过敏性反应激发子的基因 hrf A。同源性比较发现其推测产物与水稻白叶枯病菌菲律宾小种 Pxo86的 Hpa1有 97.2 %的序列一致性 ,比 Hpa1少了一个 - GGG- GG-氨基酸残基序列重复。基因经 Nde I和 Bam HI双酶切后连到含 T7启动子的高表达载体 p ET30 a(+ )上构建重组质粒 p HRF4 ,并转化宿主菌 BL2 1(DE3)产生表达菌株 BL HR4。经过 IPTG诱导之后 ,BL HR4产生一分子量为 15 .6k D的蛋白质。研究表明 ,该蛋白在性质与功能上类似于其它已发现的 harpins,即能够在烟草上引起典型的过敏性反应 ,富含甘氨酸、热稳定以及对蛋白酶敏感。因此 ,我们把该蛋白定名为 harpin Xoo。harpin Xoo还具有诱导植物抗病性的功能。更多还原

【Abstract】 A hrfA gene which encode plant hypersensitive response elicitor was cloned from Xanthomonas oryzae pv. oryzae isolate JxoIII by PCR. It encodes a predicted 140 amino acids protein that is glycine rich. Homology research showed that the protein is 97.2% identical with the Hpa1 of Xanthomonas oryzae pv. oryzae (Pxo86), but the number of the GGG GG repeats is one less. In Escherichia coli , BLHR4 strain overexpressing hrfA , the 15.6 kD protein fractionated from E.coli has been identified as the harpin Xoo . Like other harpins, harpin Xoo eli cits a typical HR in tobacco leaves. It is heat stable and appear highly sensitive to protease. Moreover, harpin Xoo has the function of inducing plant disease resistance.更多还原