辐射苜蓿愈伤组织对高温胁迫的生理响应分析

Analysis of physiological response of radiation alfalfa callus to high temperature stress

为探究高温对60Co-γ辐射苜蓿(Medicago Sativa L.)变异植株叶片诱导愈伤组织的生长和生理生化指标变化的影响,试验先确定苜蓿愈伤组织高温胁迫的温度和时间,然后根据确定好的温度对辐射苜蓿种子的第2代变异植株叶片诱导的愈伤组织(G3和G4)进行高温胁迫,分析高温胁迫对愈伤组织存活率,可溶性蛋白、可溶性糖、脯氨酸、丙二醛含量,过氧化物酶、超氧化物歧化酶、过氧化氢酶活性,以及耐热指数的影响。结果表明:苜蓿愈伤组织的增殖期为15~18 d,在45℃高温胁迫处理时,2 h、4 h和6 h愈伤组织的存活率分别为80.33%、20.73%和0,因此选择45℃高温处理1~5 h的愈伤组织进行生理生化指标的分析。3个苜蓿愈伤组织(CK、G3和G4)中可溶性蛋白含量、超氧化物歧化酶和过氧化氢酶活性均随高温胁迫时间的延长呈先增加后降低趋势,丙二醛含量呈增加趋势;CK和G3愈伤组织的可溶性糖、脯氨酸含量随高温胁迫时间的延长呈先增加后降低趋势。各指标平均耐热指数变化为CK、G3和G4愈伤组织在高温胁迫4 h、5 h和3 h平均耐热指数最高,依据3个苜蓿愈伤组织耐热指数的变化,抗高温强弱顺序为G3>CK>G4。说明G3愈伤组织可为苜蓿耐高温突变体获得提供基础材料。

To explore the effects of high temperature on the growth, physiological and biochemical of leaf callus of alfalfa(Medicago Sativa L.)variation plants by 60Co-radiation, firstly, the temperature and time of high temperature stress in the alfalfa callus were determined, and then the callus(G3 and G4) induced by second generation of mutant leaves of irradiated alfalfa seeds were subjected to high temperature stress according to the determined temperature, so as to analyze the influence of high temperature stress on the survival rate, soluble protein, soluble sugar, proline, malondia ldehyde content, peroxidase, superoxide dismutase, catalase activities, and heat tolerance index changes of callus. The results showed that the proliferation period of alfalfa callus was 15-18 days. The survival rates of callus were 80.33%, 20.73% and 0 at 2, 4 and 6 hours respectively under 45 ℃ high temperature stress. Therefore, the physiological and biochemical indexes of callus treated at 45 ℃ for 1-5 h were analyzed. The content of soluble protein and the activity of superoxide dismutase and catalase in three groups of alfalfa callus(Control, G3, G4) increased first and then decreased with the time of high temperature stress, and the content of MDA increased. The content of soluble sugar and proline in control and G3 callus increased first and then decreased with the time of high temperature stress. The average heat resistance index of control, G3 and G4 callus was the highest at 4 h, 5 h and 3 h under high temperature stress. According to the change of heat resistance index of alfalfa callus, the order of high temperature resistance was G3>CK>G4. The results indicated that G3 callus could provide basic materials for obtaining high temperature resistant mutant of alfalfa.