油菜素内酯对苦瓜抗冷性生理指标的影响

Effects of brassinolide on chilling-tolerance in bitter gourd seedlings

【目的】探讨外源油菜素内酯(BR)对低温胁迫下苦瓜幼苗生长和抗冷性生理指标的影响。【方法】采用10-2mg/LBR喷施苦瓜幼苗叶片,在低温胁迫下测定处理和对照(清水)的叶片可溶性蛋白含量、POD和SOD活性等生理指标。【结果】在低温胁迫条件下,对照与BR处理的SOD和POD活性、MDA、可溶性蛋白及可溶性糖含量呈现先升高后降低的趋势,在胁迫第4d达到最高;电导率和Pro含量呈上升趋势,而叶绿素含量呈下降趋势。低温胁迫下,与对照相比,BR处理可以明显降低叶片电解质的外渗,减缓叶片MDA含量的降低和叶绿素的降解,提高叶片SOD、POD的活性及可溶性蛋白、Pro和可溶性糖含量,减少叶片萎蔫面积和死亡率。【结论】低温胁迫条件下,外源BR处理通过调节苦瓜叶片的生理代谢,稳定膜系统的结构和功能,增强植株抗低温胁迫能力。

[ Objective ]The present experiment was conducted to study the effects of brassinolide （BR） on growth and chilling-tolerance in bitter gourd seedlings under low temperature stress. [Method]Bitter gourd seedlings at 4-leaf stage were treated with 10-2 mg/L of BR and water （control）, and placed under low temperature. The changes in POD, SOD, soluble protein content and other physiological parameters in leaves of treatment and control were determined after stress for 0-8 days. [Result]For both control and BR treatments, POD and SOD activity, MDA, soluble sugar and soluble pro- tein contents in bitter gourd seedlings increased firstly and decreased afterwards, and reached the highest after 4 days of cold stress, the conductivity and Pro content followed increasing trend, while chlorophyll showed decreasing trend. Com- pared to the control, BR treatment could significantly reduce the electrolytic exosmosis and decelerate the decrease of MDA content and chlorophyll degradation in leaves, enhance the activities of SOD and POD, contents of Pro and soluble sugar, lessen the wilting area and death rate of leaves. [ Conclusion ]Under low temperature stress, spraying BR could enhance chilling-tolerance in bitter gourd seedlings through regulating the physiological metabolism in leaves, stablizing the structure and function of cell membrane.