外源褪黑素对玫瑰高温胁迫的缓解效应

Alleviating effects of exogenous melatonin on rose under high temperature stress

[目的]高温已经成为制约玫瑰生长和生产最主要的非生物逆境因子之一。探究外源褪黑素对玫瑰耐高温能力的影响,可为解决玫瑰栽培过程中的热害问题以及玫瑰耐高温遗传改良提供实践和理论依据。[方法]以二年生‘紫枝’玫瑰盆栽苗为试验材料,研究叶面喷施100μmol·L-1褪黑素预处理对40℃高温胁迫下玫瑰叶片相关生理特性和热激蛋白基因表达的影响。[结果]高温胁迫导致玫瑰叶片水分失衡,细胞膜系统受损,光合作用受阻,次生氧化胁迫,明显抑制了玫瑰的生长。而外源褪黑素预处理后,玫瑰叶片在高温胁迫下的相对电导率(REC)和丙二醛(MDA)含量明显降低;相对含水量(RWC)和叶绿素含量(SPDA)显著升高;光系统II最大光化学效率(Fv/Fm)和净光合速率(Pn)显著提升;脯氨酸(Pro)和可溶性蛋白(SP)等渗透调节物质的含量显著增多;超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶的活性显著增强;RhHSP70、RhHSP90和RhHSP101等热激蛋白基因的表达量显著上调。[结论]高温胁迫下,施加外源褪黑素预处理能够通过提高叶片保水能力,维护细胞膜系统的稳定性和完整性,提升光合作用强度,增加渗透调节物质含量,增强抗氧化酶活性,上调热激蛋白基因表达等途径来缓解高温胁迫对玫瑰叶片产生的不利影响,从而提高了玫瑰的耐高温能力。

[Objective]High temperature stress has become a major abiotic stress factor restricting the growth and production of roses.Exploring the impact of exogenous melatonin on the heat tolerance of roses aimed to provide practical and theoretical foundations for addressing heat damage issues in rose cultivations and the genetic improvement of heat tolerance in roses.[Methods]In this study,the two year old potted‘Purple Branch’rose seedling was used as experimental materials,and the effects of folia spraying with 100μmol·L-1 melatonin on the relevant physiological characteristics and heat shock protein gene expression in rose leaves under 40℃high-temperature stress was investigated.[Results]The results showed that high temperature stress resulted in imbalances in rose leaf water content,damaged to the cell membrane system,inhibition of photosynthesis,secondary oxidative stress,and a significant inhibition of rose growth.However,after exogenous melatonin pretreatment,the relative electrical conductivity(REC)and malondialdehyde(MDA)content in rose leaves were significantly decreased under high-temperature stress.Relative water content(RWC)and chlorophyll content(SPDA)significantly increased,while the maximum photochemical efficiency of photosystem II(Fv/Fm)and net photosynthetic rate(Pn)significantly improved.proline(Pro)and soluble protein(SP)content increased significantly.The activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)significantly enhanced.The expression levels of three heat shock protein genes,including RhH⁃SP70,RhHSP90 and RhHSP101,were significantly upregulated.[Conclusion]Under high-temperature stress,exogenous melatonin pretreatment can alleviate the adverse effects on rose leaves by enhancing water retention capacity,maintaining the stability and integrity of the cell membrane system,increasing photosynthetic intensity,raising osmoregulatory substance levels,boosting antioxidant enzyme activity,and upregulating the expression of heat shock protein genes.This ultimately enhance the heat tolerance of rose.