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高温逆境是影响夏秋季蔬菜设施集约化育苗质量的主要因素之一,利用温度逆境诱导植物产生交叉适应是植物获得抗逆性的一种有效手段.为探索冷激强度对番茄幼苗高温胁迫的缓解效应,试验采用人工气候箱模拟夏季设施中的高温胁迫,研究了不同冷激温度(5、10、15℃)和冷激持续时间(10、20、30 min)对番茄幼苗生长、生物膜保护系统的影响,并研究了单次适宜冷激处理对番茄小分子热激蛋白LeHSP23.8和CaHSP18基因表达的影响.结果表明:在高温胁迫前对番茄幼苗进行冷激处理可以抑制其下胚轴的伸长和株高的生长.冷激缓解番茄幼苗高温胁迫的效应在不同冷激温度下表现出不同的变化趋势;5℃冷激处理抑制了番茄幼苗抗氧化酶活性的升高,使细胞膜透性增大,对幼苗产生伤害;10℃冷激处理对番茄幼苗高温胁迫的缓解效应随冷激时间的延长呈降低趋势;而15℃冷激处理缓解番茄幼苗高温胁迫的效应随冷激时间的延长呈增加趋势.适宜冷激温度和冷激持续时间能够诱导番茄幼苗对高温逆境的交叉适应性,在高温胁迫前将番茄幼苗进行温度为10℃、持续10 min的冷激处理效果最佳,与对照相比,显著提高了高温胁迫下番茄幼苗植株单株干质量和壮苗指数,降低了番茄幼苗叶片相对电导率和丙二醛含量,促进了脯氨酸和可溶性蛋白的积累,提高了番茄幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)3种抗氧化酶活性,并诱导了小分子热激蛋白基因LeHSP23.8和CaHSP18在常温条件下的上调表达.
High temperature adversity is one of the main factors that affect the intensive nursery quality of vegetable facilities in summer and autumn.It is an effective way to induce plants to produce cross-tolerance by using temperature adversity.To explore the effect of cold shock intensity on high temperature stress of tomato seedlings Effect, the artificial climate chamber was used to simulate the high temperature stress in summer. The effect of cold shock temperature (5, 10, 15 ℃) and cold shock duration (10, 20, 30 min) System and the effects of single cold shock treatment on the expression of small heat shock proteins LeHSP23.8 and CaHSP18 in tomato were studied.The results showed that cold stress of tomato seedlings could inhibit the hypocotyls Elongation and plant height.The effects of cold shock on the response to high temperature stress in tomato seedlings showed different trends under different cold shock temperatures. Cold shock at 5 ℃ inhibited the increase of antioxidant enzyme activities in tomato seedlings, Permeability increased injury to seedlings; 10 ℃ cold shock treatment of tomato seedlings under high temperature stress mitigation effect with cold shock time decreased; and 15 ℃ cold shock treatment The effect of high temperature stress on tomato seedlings increased with the increase of cold shock time.The suitable cold shock temperature and duration of cold shock could induce cross-adaptability of tomato seedlings to high temperature stress, and the temperature of tomato seedlings was 10 ℃ before high temperature stress , The effect of cold shock treatment for 10 min was the best. Compared with the control, the single plant dry weight and seedling index of tomato seedlings under high temperature stress were significantly increased, and the relative conductivity and MDA content of tomato seedling leaves were reduced. Proline and soluble protein accumulation increased the antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in tomato seedling leaves, and induced small The molecular heat shock protein genes LeHSP23.8 and CaHSP18 were up-regulated at room temperature.