一种新的90kD胞外蛋白激发子诱导烟草系统获得抗性研究

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

就棉疫病菌 (Phytophthora boehmeriae Saw.)培养滤液中提纯获得的 90 k D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 2 4 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 4 0 .9%～ 5 3.1% ;接种 TMV7d后处理叶片的枯斑平均直径为 1.2 3mm,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～ 10 0 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)

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.