高温胁迫下‘德钦’紫花苜蓿内源激素的变化

Changes of Endogenous Hormones of Medicago sativa L.‘Deqin'Under Heat Stress

为探析‘德钦’紫花苜蓿(Medicago sativa L.‘Deqin’)特异耐热性的原因,本试验以高秋眠级耐热型‘赛迪10’和低秋眠级热敏型‘阿尔冈金’为对照,比较35℃/30℃(昼温/夜温)高温胁迫下‘德钦’叶片IAA,CTK,GA_3和ABA 4种内源激素的变化。结果表明,具有增强植物耐热性的ABA在‘赛迪10’中含量最高并且在高温胁迫初期急剧增加,耐热性与ABA作用相反的GA_3在‘赛迪10’中始终维持较低的水平。‘德钦’的ABA和GA_3变化趋势与‘赛迪10’相似,其ABA在高温胁迫第7d小幅增加(4.16%),也能维持相对较高的水平,但GA_3累计增加量小于‘阿尔冈金’。延缓叶片衰老的IAA和CTK在‘德钦’中的含量高,累计变化率分别为74.23%和21.6%,显著高于‘阿尔冈金’和‘赛迪10’。‘德钦’特异性耐热的原因可能与其响应高温胁迫相对较早和高水平ABA有关,且IAA和CTK含量较高,GA_3含量和累计增加量较低。

To investigate the reasons of the specific heat tolerance of Medicago sativa L.‘Deqin＇,we carried out this experiment,with two cultivars as controls：‘Sardi 10＇（high fall dormancy rate and thermotolerant）and‘Algonquin＇（low fall dormancy rate and thermosensitive）,by comparing the changes of endogenous hormones（IAA,cytokinin,GA3 and ABA）of‘Deqin＇leaves under heat stress（35℃/30℃,day/night）.The results showed that ABA content which is known to enhance the thermotolerance of plants was increased sharply in the early stage of heat stress in‘Sardi 10＇.‘Sardi 10＇maintained the highest level of ABA content but lowest level of GA3 content,which was reported to reverse the effect of ABA on thermotolerance.The changing trends of ABA and GA3of‘Deqin＇are similar to‘Sardi 10＇while the ABA level of‘Deqin＇increased slightly（4.16%）at the 7th day and kept a relatively high level in the whole period.Meanwhile,the cumulative change amount of GA3on‘Deqin＇was less than that of‘Algonquin＇.For‘Deqin＇,the cumulative changes of both leaves anti-aging hormones IAA and cytokinin reached to 74.23% and 21.6%,respectively,which were significantly higher than those of‘Algonquin＇and‘Sardi 10＇.So the reasons of specific heat tolerance of‘Deqin＇could be related to its earlier response to heat stress,the capability to maintain a relatively high level of ABA and low level of GA3 for a certain period,as well as its high content of IAA and cytokinin.