棉疫病菌90kD胞外蛋白激发子诱导烟草过敏性反应的研究

Induction of hypersensitive response in tobacco by 90 kD extracellular elicitor protein from Phytophthora boehmeriae

就棉疫病菌 90kD胞外蛋白激发子诱导烟草过敏反应 (HR)过程中细胞死亡和防卫反应酶系活性变化及病程相关蛋白PR5的诱导进行研究。结果是 ,以 10nmol/L激发子溶液注射处理W38烟草叶片 ,HR枯斑周围 5mm宽组织在UV光下呈现蓝色荧光 ,对处理部位进行Evansblue染色测定结果是至 2 0h处理部位细胞全部死亡 ;激发子可诱导烟草防卫反应中苯丙氨酸解氨酶(PAL)的活性提高 ;可快速诱导PR5基因的转录。上述结果表明 90kD蛋白激发子可诱发烟草的细胞死亡、苯丙烷代谢和PR基因的表达等多条信号途径。

Induction of hypersensitive cell death, changes of phenylalanine ammonia-lyase (PAL) activity and activation of PR5 (osmotin) in tobacco by 90 kD extracellular elicitor protein, a hypersensitive response (HR) elicitor, isolated from Phytophthora boehmeriae were studied. At 24 hours after infiltration of the elicitor into tobacco (cv. W38) leaves at dosage of 10 nmol/L, a bright blue autofluorescence became visible under UV light in a ring of cells surrounding the necrosis tissue, which indicated compounds derived from the phenylpropanoid pathway were accumulated during HR. By Evans blue and trypan blue staining, it was observed that cell death occurred only in infiltrated tissue and was completed within 20 hours after treatment. Comparing with water-treated leaves, the activity of PAL, a key enzyme in plant defense response was increased in elicitor-treated leaves and in the immediate neighbor leaves. The elevated level of PAL was positively correlated with the enhancement in disease resistance in tobacco induced by elicitor that we reported previously. Moreover, the elicitor could rapidly induced transcription of PR5 in elicitor-treated tobacco leaves. Results showed that 90 kD elicitor could induce hypersensitive cell death, phenylpropanoid metabolite pathway and transcription of PR5 gene. Results also indicated that there are some systemic molecules that can transmit rapidly from infiltrated leaves to the non-elicitor-treated neighbor leaves.