| 摘要: |
| 【目的】探讨外源褪黑素对高温胁迫甜瓜幼苗的缓解效应及对耐热基因表达水平的影响，为提高设施栽培甜瓜的耐热性提供理论依据。【方法】以‘八里香’薄皮甜瓜幼苗为试验材料，用0（清水），50，100，150，200和250 μmol/L的褪黑素溶液（MT）进行叶面喷施，依次标记为MT0、MT50、MT100、MT150、MT200和MT250，预喷施处理4 d后高温（昼43 ℃/夜32 ℃）胁迫4 d，以喷施清水常温（昼32 ℃/夜20 ℃）处理为对照（CK）。测算甜瓜幼苗的热害指数、生长指标、光合参数、抗氧化酶活性、脯氨酸及丙二醛含量，筛选出最适外源MT浓度。以筛选出的MT浓度为处理，以喷施清水高温（昼43 ℃/夜32 ℃）处理(MT0)、喷施清水常温（昼32 ℃/夜20 ℃）处理(CK)为对照，测定HSP70和HSP90基因的表达量，分析MT对甜瓜幼苗耐热性的影响。【结果】喷施外源MT能缓解高温胁迫下甜瓜幼苗出现的萎蔫失水等热害症状。随着MT喷施浓度的增加，各生长指标（株高除外）呈现先上升后下降的变化趋势，与MT0组相比，MT200组甜瓜幼苗的株高、茎粗、根长、鲜质量、干质量分别增加36.73%，22.61%，10.62%，51.85%和28.00%；MT200组甜瓜幼苗热害指数最低，较MT0组降低46.96%。MT200组甜瓜幼苗的蒸腾速率（Tr）、净光合速率（Pn）、气孔导度（Gs）较MT0组分别显著升高545.45%，83.85%和53.85%，胞间CO2浓度（Ci）较MT0组显著降低26.48%。预喷施MT后，甜瓜幼苗抗氧化酶活性呈不同程度增加，其中MT200组最高，SOD、POD、CAT活性分别比MT0组显著提高69.69%，33.29%和40.94%。甜瓜幼苗丙二醛含量随着MT喷施浓度增加呈现先下降后上升的变化趋势，MT200组最低，与MT0组相比降低59.58%，且与CK差异不显著；脯氨酸含量随着MT喷施浓度增加呈先上升后下降的变化趋势，MT200组Pro含量最高，较MT0组增加225.6%。MT200组甜瓜幼苗HSP70和HSP90基因表达较MT0组显著上调，分别提高1.81和1.13倍。【结论】外源MT对提高甜瓜耐热性有积极作用，可通过调节抗氧化途径及耐热基因表达缓解高温对甜瓜幼苗的伤害，且当喷施浓度为200 μmol/L时效果最佳。 |
| 关键词: 褪黑素（MT) 高温胁迫 甜瓜幼苗 抗氧化酶 热激蛋白 |
| DOI：10.13207/j.cnki.jnwafu.2025.07.015 |
| 分类号: |
| 基金项目:吉林省科技发展计划项目“甜瓜产业技术研发创新团队”（20230508022RC） |
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| Effects of exogenous melatonin on alleviating effect and heat-resistant gene expression in muskmelon seedlings under high temperature stress |
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TENG Wei1, LI Tingting1, MA Yan1, LIU Xiyuan1, LIU Ziming2, GENG Wei1
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1.Jilin Provincial Institute of Vegetable and Flower Science,Changchun，Jilin 130033,China;2.Panshi City Hongqiling Town Comprehensive Service Center,Jilin,Jilin 132311,China
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| Abstract: |
| 【Objective】This research aimed to investigate the effects of exogenous melatonin on the heat tolerance of muskmelon seedlings under high temperature stress,and to provide theoretical basis for improving the heat tolerance of muskmelon cultivated in facilities.【Method】‘Baliang’ thin-skinned Muskmelon seedlings were sprayed with 0 (water),50,100,150,200 and 250 μmol/L melatonin solution (MT),labeled as MT0,MT50,MT100,MT150,MT200 and MT250,respectively.After 4 days of pre spraying treatment,the seedlings were kept under high temperature (43 ℃ in the day/32 ℃ at night) for 4 days,with seedlings sprayed with water under normal temperature (32 ℃ in the day/20 ℃ at night) as the control (CK).The optimum concentration of exogenous MT was selected by measuring the heat injury index,growth index,photosynthetic parameters,antioxidant enzyme activity,proline content and malondialdehyde content of muskmelon seedlings.The optimum MT concentration treatment was set,with the treatment(MT0) of spraying water under high temperature (43 ℃ in the day/32 ℃ at night) and the treatment(CK) of spraying water under normal temperature (32 ℃ in the day/20 ℃ at night) as the control,to determine the expression levels of HSP70 and HSP90 genes.The effects of MT on heat resistance of muskmelon seedlings were analyzed.【Result】Spraying exogenous MT could relieve heat damage caused by high temperature stress on muskmelon seedlings,such as wilting and water loss.With the increase of spraying MT concentration,all growth indexes (except plant height) firstly increased and then decreased.Compared with MT0 group,plant height,stem diameter,root length,fresh weight and dry weight of muskmelon seedlings in MT200 group were increased by 36.73%,22.61%,10.62%,51.85% and 28.00%,respectively.The heat damage index of muskmelon seedlings in MT200 group was the lowest,which was 46.96% lower than that in MT0 group.Transpiration rate (Tr),net photosynthetic rate (Pn) and stomatal conductance (Gs) in MT200 group were significantly increased by 545.45%,83.85% and 53.85% compared with those in MT0 group,respectively,and intercellular CO2 concentration (Ci) was significantly decreased by 26.48% compared with that in MT0 group.After MT pre-spraying treatment,the activities of antioxidant enzymes (SOD,POD and CAT) of muskmelon seedlings were increased in different degrees,with the activities in MT200 group being the highest.SOD,POD and CAT activity were significantly increased by 69.69%,33.29% and 40.94% compared with those in MT0 group,respectively.The content of malondialdehyde in muskmelon seedlings decreased first and then increased with the increase of MT concentration,with the lowest value observed in MT200 group,which was 59.58% lower than that in MT0 group,and the difference was not significant compared with CK.Proline content increased first and then decreased with the increase of spraying MT concentration,with the highest content observed in MT200 group,which increased by 225.6% compared with that in MT0 group.The gene expression of HSP70 and HSP90 of muskmelon seedlings in MT200 group were significantly up-regulated compared with those in MT0 group,which were increased by 1.81 and 1.13 times,respectively.【Conclusion】Exogenous MT has a positive effect on improving the heat resistance of muskmelon,and can alleviate the damage of high temperature on muskmelon seedlings by regulating the antioxidant pathway and heat resistance gene expression.The best spraying concentration is 200 μmol/L. |
| Key words: melatonin (MT) high temperature stress muskmelon seedlings antioxidant enzymes heat shock protein |
