水杨酸诱导水稻幼苗抗瘟性的生化机制

 以0.01mM水杨酸(SA)喷雾处理或稻瘟菌孢子悬浮液接种稻苗后,叶片中苯丙氨酸解氨酶(PAL)和定位于细胞不同部位的过氧化物酶(POD),特别是与细胞壁结合的POD和细胞间隙POD的活性迅速升高,但没有明显的新POD同功酶带出现。同时叶片中木质素含量迅速增加。在SA处理后的稻叶中提取到能抑制稻瘟菌分生孢子萌发、含有Momilactone A的抑菌物质,并检测到分子量分别为48、52、59、106.5KDa的碱性病程相关蛋白(PRs)。这些生化指标的时序变化与SA诱导抗瘟性的表现相吻合。对SA诱导水稻幼苗抗瘟性的可能生化机理作了归纳。

BIOCHEMICAL MECHANISMS OF SALICYLIC ACID INDUCED RESISTANCE TO RICE SEEDLING BLAST

After rice seedling leaves were sprayed with 0. 01 mM salicylic acid (SA) or inoculated with Pyricularia oryzae , the activities of phenylalanine amonnia lyase (PAL) and different cellular located peroxidase (POD), especially those located in intercellular fluid and ionically bound with cell wall, increased significantly compared with those in water controlled leaves, but no new isozyme of POD was detected. Meanwhile, increment of lignin content was also observed in SA treated or inoculated leaves. A kind of momilactone A containing, phytoalexin like fungitoxic substance, which shown inhibitory effect on spore germination of P . oryzae in vitro , was extracted from leaves of rice seedlings pretreated with SA. Four basic pathogenesis related proteins (PRs) with MW 48, 52, 59 and 106. 5 KDa respectively were detected by SDS PAGE and nondenaturing PAGE. Time courses of these indices coincide with the expression of SA induced resistance exactly. Thus, elevated content of lignin; increased activities of PAL and POD; accumulation of fungitoxic substance and appearance of PRs were considered to be involved in the biochemical mechanisms of SA induced resistance of rice seedlings to blast.