甜瓜幼苗叶片内源一氧化氮和蔗糖代谢对低温胁迫的响应

Response of Endogenous Nitric Oxide and Sucrose Metabolizing to Chilling Stress in Melon Seedlings

以低温敏感型甜瓜品种‘XL-1’和耐低温型品种‘红优’为试材,采用6℃低温处理0、1、3、6、12、24h及3d、5d和7d,研究低温胁迫下甜瓜幼苗叶片中NO合成和蔗糖代谢的变化特征。结果表明:(1)低温胁迫能提高甜瓜幼苗叶片中硝酸还原酶(NR)活性,诱导促进NO生成,其中耐低温型甜瓜‘红优’中NO对低温的响应时间更早,变化幅度更大。(2)与对照相比,低温胁迫处理提高了2种甜瓜幼苗叶片中蔗糖、果糖和葡萄糖含量,增加了蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)、酸性转化酶(AI)和中性转化酶(NI)活性,降低了淀粉含量。(3)低温胁迫处理使2种甜瓜叶片中渗透调节物质可溶性糖、可溶性蛋白、脯氨酸的含量上升。研究发现,低温胁迫通过增加甜瓜体内NO合成酶的活性刺激体内NO合成,通过促进蔗糖代谢相关酶的活性,提高蔗糖、果糖和葡萄糖的含量,从而响应低温胁迫,且低温胁迫诱导的糖分物质积累时间晚于NO的产生时间。

In order to investigate the changes of NO synthesis and sucrose metabolism in melon seedlings under chilling stress,cultivar‘Hongyou’(chilling-tolerant)and‘XL-1’(chilling-sensitive)melon seedlings were treated with 6℃for 0,1,3,6,12,24 h,3 d,5 dand 7 din climate chambers.The results showed that:(1)chilling stress increased the activity of nitrate reductase(NR)and induced NO production.The response time and change of NO to chilling stress were earlier and more obvious in chilling-tolerant cultivar‘Hongyou’.(2)Compare with the control,the chilling stress condition increased sucrose,fructose and glucose contents,enhanced the activities of sucrose phosphate synthase(SPS),sucrose synthase(SS),acid invertase(AI),neutral invertase(NI),and decreased starch content.(3)The contents of soluble sugar,soluble protein and proline in the leaves of the two melon seedlings increased under chilling stress.These results indicated that melon seedlings could respond to chilling stress by inducing NO and carbohydrate generation.In addition,the accumulation of sugar substances induced by chilling stress was later than the production of NO.