ALA对高温胁迫下苜蓿属3个品种叶片生理的影响

Effect of 5-aminolevulinic Acid on Leaf Physiology of Three Cultivars of Medicago under High Temperature Stress

为探究5-氨基乙酰丙酸(5-aminolevulinic acid,ALA)对苜蓿属(Medicago)植物耐热性的影响,以苜蓿属3个品种盆栽苗为材料、以常温无ALA(CK)和高温胁迫无ALA(Heat)为对照,研究不同浓度ALA(5,10,15,20,25 mg·L^(-1))预处理对高温胁迫后叶片生理的影响。结果表明,42℃高温胁迫后,3个品种叶片的相对电导率和MDA含量显著升高(P<0.05),其中WL525HQ、德钦苜蓿和楚雄南苜蓿相对电导率较CK分别升高205.844%,206.589%,226.741%,MDA含量则升高112.649%,110.140%,124.664%,且叶片严重失绿。但喷施不同浓度ALA后可有效减少MDA含量和相对电导率(P<0.05),缓解叶片失绿,同时提高叶绿素a、b和总叶绿素含量(P<0.05),并且叶片中SOD、POD和CAT活性较高(P<0.05)。通过双因素方差分析表明,在影响苜蓿各耐热性指标的因素中,处理和品种虽有显著影响,但其作用大小为处理>品种。以8个生理指标进行隶属函数分析表明,20 mg·L^(-1)ALA预处理对3个品种缓解高温胁迫的效果最好。

To explore the effect of 5-aminolevulinic acid(ALA)on heat tolerance of Medicago plants.Three cultivars of potted seedlings of Medicago were used as materials to study the effects of different concentrations of ALA(5,10,15,20 and 25 mg·L^(-1))pretreatment on the leaf physiology of Medicago plants after high temperature stress,with no ALA at room temperature(CK)and no ALA at high temperature stress(Heat)as controls.The results showed that the relative conductivity and MDA content of the leaves of the three varieties increased significantly(P<0.05)after high temperature stress at 42℃.Compared with CK,the relative conductivity of M.sativa‘WL525HQ’,M.sativa‘Deqin’,M.hispida‘Chuxiong’increased by 205.844%,206.589%and 226.741%,respectively;and the MDA content increased by 112.649%,110.140%and 124.664%,respectively,and the leaves were severely chlorotic.However,spraying different concentrations of ALA effectively reduced MDA content and relative conductivity(P<0.05),reduced leaf greening while increasing chlorophyll a,b and total chlorophyll content(P<0.05),and higher SOD,POD and CAT antioxidant enzyme activities in the leaves(P<0.05).A two-way ANOVA showed that among the factors affecting each heat tolerance index in Medicago plant,treatment and variety had a significant effect,although the magnitude of the effect was:treatment>variety.Membership function analysis with 8 physiological indicators showed that 20 mg·L^(-1) ALA pretreatment was most effective in alleviating high temperature stress in three cultivars.