腐烂病菌侵染对苹果愈伤组织防御酶活性及丙二醛含量的影响

以苹果树腐烂病菌LXS080601、感病苹果品种‘富士’和抗病砧木‘平邑甜茶’愈伤组织为材料,测定腐烂病菌侵染后,愈伤组织内过氧化物酶（POD）、多酚氧化酶（PPO）、超氧化物歧化酶（SOD）和苯丙氨酸解氨酶（PAL）活性及丙二醛（MDA）含量的动态变化。结果显示,接种LXS080601后,‘富士’愈伤组织的发病严重度和病情指数均明显大于‘平邑甜茶’;感病品种MDA含量上升速度快,于接种后3 d增幅为28.02%,且变幅较大,为–0.32%~36.39%,而抗病砧木MDA含量变化较小,仅为–2.17%~7.46%。同时,腐烂病菌侵染提高了愈伤组织内4种防御酶活性,接种后1~2 d,PPO和POD酶活性达到高峰,接种后3~4 d,PAL和SOD酶到达活性高峰;除PPO外,‘平邑甜茶’PAL、SOD和POD酶活性变化均明显高于‘富士’,且整个侵染过程酶活性维持在较高水平,而‘富士’体内3种酶活性快速下降至对照水平,表明‘平邑甜茶’通过提高抗氧化酶活性减少体内活性氧的积累,降低膜脂过氧化产物MDA的形成,增强了对腐烂病菌侵染的抗性。

Effects of Valsa mali var. mali Infection on Defense Enzymes Activity and MDA Content in Apple Callus

In this study, susceptible cultivar （＇Fuji＇） and resistant rootstock （Malus hupehensis） were used to investigate the dynamic changes of defense enzymes activity and MDA content in the callus infected with V. mali isolate LXS080601. After inoculation, apple callus disease index, MDA content and activities of defense enzymes including phenylalanine ammonia lyase （PAL）, polyphenol oxidase （PPO）, superoxide dismutase （SOD） and peroxidase （POD） were determined. The results showed that, the disease severity and infection index of ＇Fuji＇ callus were significantly higher than M. hupehensis infected with LXS080601. MDA content increased in the callus inoculated with LXS080601. Specially, MDA content increased from -0.32% to 36.39% in ＇Fuji＇ cal- lus, the changes of which were more noticeable than those in the resistant rootstock from -2.17% to 7.46%. In addition, four kinds of defense enzymes activities increased in callus after LXS080601 infection. PPO and POD activities peaked at one to two days post inoculation while PAL and SOD activities reached highest at three to four days post inoculation. Except for PPO, the activity changes of other three enzymes were significantly high- er in M. hupehensis than in ＇Fuji＇. After reaching the peaks, the activities of PAL, SOD and POD in ＇Fuji＇ de- creased dramatically whereas the enzymes activities in M. hupehensis declined very slowly and maintained higher activities during the whole infection. The results suggested that M. hupehensis obtained resistance against V. mali infection in part by reducing the accumulation of reactive oxygen species and the production of MDA through enhanced antioxidant defense system.