根肿病胁迫下外源SA对不结球白菜抗性诱导和生理生化的影响

摘要

To figure out the protective effect of exogenous salicylic acid (SA)on inducing clubroot resist-ance of pak-choi and the reactions of physiological indicators on susceptible pak-choi plants,with 'Xi-naiqing'pak-choi as the tested material,after inoculated clubroot disease(Plasmodiophora brassicae Wor) by the method of the soil bacteria inoculation,we investigated the effects of 0.2~0.8 mmol·L-1 exoge-nous salicylic acid (SA)on pak-choi plants growth,inducing resistance,reactive oxygen and defense en-zyme activities of leaf and root infected clubroot,with the possible action mechanism of SA discussed.The results showed that:(1)the clubroot disease significantly affected the growth and increased the damage of membrane lipid peroxidation.(2)The best effect on the alleviation of clubroot disease stress damage was observed in the treatment of 0.6 mmol·L-1 SA.At this concentration,the plants growth,resistance of clubroot disease.(3)The activities of superoxide dismutase(SOD),peroxidase(POD),ascorbate peroxi-dase(APX),polyphenol oxidase (PPO),phenylalanine ammonialyase (PAL),glutathione reductase (GR) were were increased significantly in leaves and roots,while malondialdehyde (MDA),hydrogen peroxide (H2O2 )contents and the production rate of superoxide anion(O-· 2 )were significantly decreased.The above results indicated that dosage effect of SA existed on the alleviation of clubroot disease stress in pak-choi plants,and the best alleviating effect on clubroot disease stress damage was 0.6 mmol·L-1 SA by irriga-ting at the plant roots,which was favorable for the plant to grow,and improve the ability of resistance of clubroot disease.%以不结球白菜'新矮青'为试验材料,采用菌土接种法接种根肿病菌,研究不同浓度(0.2~0.8 mmol·L-1)的外源水杨酸(SA)对根肿病胁迫下不结球白菜植株抗性诱导和感病植株生长的影响,以及植株叶片和根系中防御酶系统的变化规律,探讨外源SA对防治不结球白菜根肿病的可行性.结果显示:(1)根肿病显著影响不结球白菜的生长,加剧植物的膜脂过氧化程度;适宜浓度的外源SA能不同程度地缓解不结球白菜所受根肿病的侵害,并以0.6 mmol·L-1 SA处理效果最好.(2)外源SA显著降低了根肿病的发病率和病情指数,提高了抗根肿病的诱抗效果,并缓解感病对不结球白菜的生长抑制,显著促进感病植株的生长.(3)外源SA提高了不结球白菜叶片和根系中的超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸-过氧化物酶(APX)的抗氧化酶活性,以及多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、谷胱甘肽还原酶(GR)的防御酶活性;显著降低了植株叶片和根系中的MDA、H2O2含量及O-·2产生速率.研究表明,外源SA诱导不结球白菜对根肿病的抗性,缓解根肿病的伤害,且具有剂量效应,以根部灌施0.6 mmol·L-1 SA的效果最好;在根肿病的胁迫下,SA可提高不结球白菜植株抗氧化酶和防御酶的活性,增强渗透调节能力和细胞活性氧清除能力,降低根肿病对植株的伤害,从而促进生长.