摘要
Products of plant resistance ( R ) genes Pto and Cf contain distinct domains, and have different cellular localization. It is intriguing to compare the development mechanisms of resistance conferred by the two R genes. In the present report, two hypersensitive response (HR) initiation systems were employed to study the time_course expression induced by Avr / Cf interaction of the genes encoding Pti4, Pti5 and Pti6 which interact directly with Pto: (1) Seeds of tomato (Lycopersicon esculentum Mill.) containing complementary gene pairs Avr 4/ Cf _4 and Avr 9/ Cf _9 were obtained through crossing. Their seedlings developed HR under room temperature. (2) Avr / Cf seedlings grew normally at 33 ℃. When the temperature was shifted down to 25 ℃, HR occurred within hours in the seedlings. Results of both experiments showed that expression of Pti4, Pti5 and Pti6 was induced upon development of hypersensitive necrosis in Avr / Cf seedlings. However, the expression levels and patterns of these Pti s differed. This finding indicated that these Pti s function complementarily, and might be involved in regulation of both Pto and Cf _conferred resistance.
植物抗病基因Pto和Cf产物具完全不同的结构域 ,其细胞定位也不同。二者决定的抗病性产生机制的异同令人关注。采用两种过敏性反应 (hypersensitiveresponse ,HR)产生系统研究了Pto互作蛋白Pti4、Pti5和Pti6编码基因在Avr/Cf互作中的时序表达 :(1)通过杂交方法获取同含互补基因对Avr4 /Cf_4和Avr9/Cf_9的番茄 (Lycoper siconesculentumMill.)种子。常温下这些种子发芽后形成的苗产生HR坏死斑。 (2 )先将Avr/Cf苗置于 33℃下培养 ,此时番茄苗生长正常 ,不形成HR坏死斑。然后将温度降至 2 5℃ ,数小时内这些苗即形成HR坏死斑。不同方法研究结果均表明 ,随Avr/Cf苗中HR坏死斑的形成 ,Pti4、Pti5和Pti6均受显著诱导表达。但它们的表达水平和动态不同。这些结果表明 ,这些Pti在功能上互补 ,可能同时涉及Pto和Cf决定性抗性的调节作用。
基金
国家自然科学基金(3 0 0 70 492 )。~~
