茉莉酸诱导水稻幼苗对稻瘟病抗性作用研究

Effect of jasmonic acid on induced resistance of rice seedlings to Magnaporthe grisea

外源茉莉酸处理可以显著减轻水稻幼苗稻瘟病的发生。JA诱导稻苗产生抗病性的有效浓度是0．1～0．00lmmol／L，喷雾处理后2d接种稻瘟病菌获得最佳的抗病效果。0．1mmol／LJA喷雾处理后2d接种稻瘟病菌，水稻幼苗的诱抗效果都超过了55％。JA处理的诱导抗性可以维持15d左右。用0．1mmol／LJA二次强化处理水稻幼苗可以增强诱导抗病性，延长抗性的持续期。JA诱导水稻幼苗抗性机制的结果表明：0．1mmol／LJA处理可以诱导水稻体内苯丙氨酸解氨酶、过氧化物酶活性和木质素升高。

Rice blast was inhibited by the treatment of exogenous jasmonic acid （JA）, but no inhibitory effect of JA was detected on spore germination and mycelium growth of the pathogen in vitro. Therefore, the reduction of disease severity in JA-treated rice plants was due to JA-induced resistance to blast. The active concentration of JA to induce rice blast resistance was at a range of 0.1 -0. 001 mmol/L. The proper interval between induction treatment and challenge inoculation was 2 d. When rice were sprayed with 0.1 mmol/L JA and inoculated with fungal spore suspension 2 d later, the blast severity reduced by 55 percents and the resistance was observed to last up to 15 d after treatment. Repeating JA treatment of rice with an interval of 5 d was demonstrated to increase the resistant effect and lasting resistance to the pathogen. The activities of phenylalanine amonnialyase and peroxidase of rice leaves sprayed with 0.1 mmol/L JA, increased significantly compared with those in control. Meanwhile, increasing of lignin levels was also observed in leaves of rice seedlings after JA treatment.