葡萄中褪黑素对NaHCO3胁迫的响应及外源褪黑素缓解NaHCO3胁迫的作用机制

The response of melatonin to NaHCO_3 stress and the mechanism of exogenous melatonin treatment in alleviating NaHCO_3 stress in grapevine

以一年生‘福客’(‘Frontenac’)葡萄(Vitis sp.)盆栽扦插苗为试材,研究85 mmol·L^(-1) NaHCO_3胁迫处理对葡萄不同器官褪黑素、5-羟色胺和2-羟基褪黑素含量的影响,并进行外源浇灌褪黑素处理,研究外源褪黑素对碱胁迫下有机渗透调节物质和离子含量及离子转运相关基因表达的影响。结果表明,NaHCO_3胁迫后,葡萄根、茎和叶中的褪黑素含量降低,以根和茎中的降低幅度较大,葡萄根系中5-羟色胺的含量显著增加,褪黑素的代谢产物2-羟基褪黑素在根中大幅降低,却在叶片中大量积累;NaHCO_3胁迫下,外源褪黑素显著降低了叶片O_2^(-·)产生速率和H_2O_2含量,增加了有机渗透调节物质可溶性糖、可溶性蛋白和脯氨酸含量,降低了叶片中Na^+含量,但增加了叶片中K^+含量。褪黑素处理提高了NaHCO_3胁迫下葡萄叶片中VvNHXP和VvHKT家族基因的表达。综上,碱胁迫下根系合成褪黑素代谢前体物质5-羟色胺,并向地上部运输,主要在叶片中清除自由基,调节有机渗透调节物质含量,并通过上调离子转运蛋白VvNHXP和VvHKT家族基因的表达,维持胞内离子平衡,进而缓解NaHCO_3对膜系统的伤害。

The one-year-old potted ‘Frontenac＇ grapevines（Vitis riparia） were used as materials to investigate the effect of 85 mmol·L^（-1） NaHCO_3 stress on melatonin,serotonin and 2-hydroxy melatonin in different organs of grapevines,and exogenous melatonin was irrigated to study the effect of melatonin on the contents of organic osmotic adjustment substances and ions as well as the expression of ion transport-related genes under NaHCO_3 stress.The results show that melatonin content was reduced in leaves and especially in roots and stems under NaHCO_3 stress.In contrast,the content of serotonin in roots were significantly increased under NaHCO_3 treatment,2-hydroxy melatonin in the roots were significantly reduced,and 2-hydroxy melatonin in leaves were increased.Under NaHCO_3 stress,O_2^（-·） production rate and H_2O_2 content were significantly reduced,while contents of organic osmotic adjustment substances,soluble sugar,soluble protein,proline and K＋,were increased by exogenous melatonin application;Na~＋ content was significantly decreased;the expression levels of VvNHXPand VvHKT family genes were significantly increased in leaves by exogenous melatonin application.In conclusion,serotonin was produced in root and thereafter transported to aerial organs to scavenge free radicals and increase organic osmotic adjustment substances,additionally,the expression of ion transport-related genes,VvNHXP and VvHKT,were up-regulated to maintain ion balance and reduce the membrane injury under NaHCO_3 treatment.