一种新的90 kD胞外蛋白激发子诱导烟草系统获得抗性研究

 就棉疫病菌(Phytophthora boehmeriae Saw.)培养滤液中提纯获得的90 kD胞外蛋白激发子诱发烟草系统获得抗性进行了研究。以10 nmol/L激发子溶液注射处理Samsun NN烟草叶片24 h后,在处理叶片及其上、下各2片叶片接种TMV,结果是处理叶及其上、下各2片叶片上的枯斑数显著少于对照,诱抗防效达40.9%~53.1%;接种TMV7d后处理叶片的枯斑平均直径为1.23mm,显著小于对照叶片上的枯斑直径2.97mm,但是处理叶片的上、下叶片上的枯斑平均直径与对照没有显著差别。以10 nmol/L激发子溶液注射处理Samsun NN烟草叶片分别立即接种或于1、2、4、7、15 d接种TMV,结果证明该激发子诱导烟草对TMV的抗性以处理后第1d至第4 d接种为较好,防效达30.2%~5 0.4%;处理后立即接种和第7d接种TMV诱抗防效仅4%左右,处理叶片上的枯斑数与对照没有显著差别,表明较强的诱导抗性可持续时间<7d。用不同浓度激发子处理烟叶,所测定的0.5~100 nmol/L各浓度均可显著地诱发烟草对TMV产生获得抗性,诱导抗性效果为34.9%~5 8.2%,诱导抗性效果随浓度的降低呈下降趋势。以10 nmol/L激发子溶液注射处理W38烟草叶片,2 d后分别注射接种烟草野火病菌(Pseudomonas syringae pv.tabaci)菌液或喷雾接种烟草赤星病菌(Alternaria alternata)分生孢子,结果是,注射接种烟草野火病菌5d后处理叶片及其上、下叶片上的野火病病斑均显著小于对照;处理叶片上的赤星病病斑数及病斑面积明显小于对照,表明该激发子可诱导烟草对野火病和赤星病产生抗性。上述结果表明,90kD蛋白激发子诱导烟草产生的获得抗性是一种典型的系统获得抗性,该系统获得抗性对病原菌具广谱抗性。

SYSTEMIC ACQUIRED RESISTANCE INDUCED BY A NEW KIND OF 90 kD EXTRACELLULAR ELICITOR PROTEIN

Systemic acquired resistance to TMV, Pseudomonas syringae pv. tabaci and Alternaria alternata in tobacco elicited by 90 kD extracellular elicitor protein, a hypersensitive responses (HR) elicitor on tobacco leaves purified from the culture filtrate of Phytophthora boehmeriae was studied. Inoculation of TMV at 24 h after infiltration of tobacco leaves (cv. Samsun harboring N gene) with the elicitor at dosage of 10 nmol/L, resulted in fewer and smaller visible necrotic lesions on treated leaves than that on buffer infiltrated ones. Fewer lesions were also observed on the 1st and 2nd upper or lower leaves of the elicitor treated leaf on the same plant when TMV was inoculated, but the average diameter of necrotic lesion did not significantly differ from that of the control leaves. The reduction rates in lesion number were about 40.9%-53.1% and the induced resistance lasted for about seven days. All the dosages ranging from 0.5 to 100 nmol/L tested could trigger the resistance significantly and the resistance level (34.9%-58.2%) was positively correlated with the dosages used. Whereas, the elicitor only provided low level of induced resistance to TMV (4%) when the treated leaves were inoculated immediately or at seven day after elicitor applied. Similar induced resistance by elicitor protein against Pseudomonas syringae pv. tabaci and A. alternata was also found in this study. When inoculation with P. syringae pv. tabaci or A. alternata performed on tobacco plants (cv. W38) at 48 h after elicitor treatment, smaller or fewer lesions which significantly differed from the control were observed on treated leaves and their upper and lower non elicitor treated leaves. Results showed that the induced resistance of tobacco by 90 kD extracellular elicitor protein from P. boehmeriae was typically a systemic acquired resistance (SAR) characterized by systemicity, durability and a broad spectrum, which indicated the 90 kD protein elicitor is a kind of natural specific trigger for SAR. Results also indicated an endogenous mobile signaling mechanism be elicited and functioned between treated leaves and their upper or lower non elicitor treated ones, where it induced strong responses without HR.