苯丙氨酸解氨酶在诱导黄瓜幼苗抗寒性中的作用  

Roles of phenylalanine ammonia-lyase in low temperature tolerance in cucumber seedlings

作　　者：董春娟[1] 李亮[1] 曹宁[1] 尚庆茂[1] 张志刚[1] 

机构地区：[1]中国农业科学院蔬菜花卉研究所/农业部园艺作物生物学与种质创制重点实验室,北京100081

出　　处：《应用生态学报》2015年第7期2041-2049,共9页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(31101548);现代农业产业技术体系建设专项(CARS-25);公益性行业(农业)科研专项(201303014)资助

摘　　要：为了探讨苯丙氨酸解氨酶(PAL)在诱导黄瓜幼苗抗寒性中的作用,采用喷施特异抑制剂(AOPP)的方法控制PAL活性,测定幼苗抗寒性的变化.结果表明:低温可以诱导黄瓜幼苗叶片中PAL的基因表达和活性升高;喷施AOPP显著抑制了叶片中PAL活性,减少了酚类和类黄酮物质的积累.低温对黄瓜幼苗造成显著伤害,AOPP预处理加剧了低温对幼苗的损伤,幼苗抗寒性降低.与对照相比,幼苗叶片中相对电解质渗漏率和丙二醛(MDA)含量显著升高,PSII最大光化学效率(Fv/Fm)降低,光化学猝灭参数Y(NO)升高,胁迫相关基因(PR1-1a、COR47、P5CS、HSP70)的诱导表达受到抑制.低温导致黄瓜幼苗叶片中H2O2积累,还原型抗坏血酸(As A)含量降低,脱氢抗坏血酸(DHA)含量升高,As A∶DHA减小;喷施AOPP的幼苗中抗氧化酶(过氧化氢酶CAT、抗坏血酸过氧化物酶APX)活性显著低于对照,H2O2过量积累,As A∶DHA更低.施用H2O2清除剂可以有效缓解喷施AOPP引起的低温损伤加剧,而施用CAT抑制剂的幼苗对低温胁迫更敏感.表明低温诱导了PAL活性升高,促进了苯丙烷类次生代谢产物的合成,提高了胞内抗氧化酶活性,可有效清除活性氧分子,维持As A氧化还原状态,缓解低温引起的光损伤和氧化损伤.To reveal the roles of phenylalanine ammonia-lyase （PAL） in low temperature tolerance in cucumber seedlings, a specific PAL inhibitor （AOPP） was sprayed to the seedlings, and then the stress tolerance was determined. The results suggested that both gene expression and enzymatic activity of PAL in cucumber leaves were induced under low temperature. The seedlings pretreated with AOPP showed lower PAL activity and less accumulation of phenolics and flavonoids. Low tem- perature caused damages in cucumber seedlings, and pretreatment of AOPP aggravated these dama- ges. Compared to the control, the seedlings pretreated with AOPP showed significantly higher rela- tive electrolyte leakage and MDA production, lower maximum photochemical efficiency of PSII （Fv/IY＇m ） but higher photo-chemical quenching coefficient Y（ NO）, and reduced expression of low temperature-responsive genes （PR1-la, COR47, P5CS and HSP70）. In cucumber seedlings, low temperature stress induced the accumulation of H202, increased the contents of ascobate （AsA） but decreased the contents of dehydroascobate （DHA） , and thus reduced the value of AsA ： DHA. In the AOPP-pretreated seedlings, the activities of antioxidant enzymes （CAT and APX） were signifi- cantly repressed, and excess H202 accumulated. The value of AsA： DHA was also lower than the control. Furthermore, co-application of H202 scavenger alleviated the low temperature-induced damages in the AOPP-pretreated seedlings, while co-application of a CAT inhibitor made the seed- lings more sensitive to low temperature stress. These results indicated that under low temperature stress, the enhanced activities of PAL could increase the biosynthesis of phenylpropanoid com- pounds and activate the cellular antioxidant enzymes, which could scavenge the excess ROS and maintain the cellular redox status, and thereby reduce the photo- and oxidative damages caused by low temperature stress.

关 键 词：黄瓜 苯丙氨酸解氨酶 抑制剂 低温胁迫 抗性 

分 类 号：S642.2[农业科学—蔬菜学]