干旱胁迫下陇中紫花苜蓿对外源精胺的生理响应

doi:10.3864/j.issn.0578-1752.2025.04.005

摘要/Abstract

摘要：

【目的】精胺（spermine, Spm）可提高植物对非生物胁迫的耐受力，减少非生物胁迫对植物造成的伤害。探究干旱胁迫下外源Spm对紫花苜蓿抗旱性的影响，为外源Spm提高紫花苜蓿抗旱性提供理论依据，进而为利用外源Spm增强植物抗旱性的应用提供科学依据。【方法】以陇中紫花苜蓿（Medicago sativa L. cv. Longzhong）为试验材料，使用聚乙二醇6000模拟干旱胁迫。研究在正常水分和干旱条件下，根施浓度为0.1、0.5和1.0 mmol·L^-1Spm后陇中苜蓿株高、叶片相对含水量（RWC）、光合色素含量、气体交换参数、抗氧化酶活性、抗氧化剂含量、超氧阴离子（$O^{\bar{.}}_{2}$）含量、过氧化氢（H₂O₂）含量、丙二醛（MDA）含量和渗透调节物质含量等生理指标的变化特征。【结果】干旱胁迫下，外源Spm可增加陇中苜蓿的株高和叶片RWC，减缓叶绿素a、叶绿素b（Chlb）和类胡萝卜素的降解，提升叶片净光合速率、蒸腾速率和气孔导度，降低胞间二氧化碳浓度，增强超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性，提高抗坏血酸（ASA）含量、ASA/氧化型抗坏血酸（DHA）比值、谷胱甘肽（GSH）含量和GSH/氧化型谷胱甘肽（GSSG）比值，降低DHA和GSSG含量，增强抗坏血酸过氧化物酶和谷胱甘肽还原酶活性，减少$O^{\bar{.}}_{2}$和H₂O₂的产生，抑制MDA积累，增加脯氨酸和可溶性糖含量。通过主成分分析及计算各个处理下所有生理指标的平均隶属函数值，结果表明，在正常水分条件下施用Spm对紫花苜蓿的生长没有影响，而干旱条件下施用Spm可提高干旱胁迫下陇中苜蓿的抗旱性，其中0.5 mmol·L^-1 Spm的提升效果最佳。进一步冗余分析表明，0.5 mmol·L^-1 Spm主要通过减缓叶片Chlb的降解，提高ASA-GSH循环和CAT活性来增强陇中苜蓿的抗旱性。【结论】外源Spm能够通过减缓光合色素的降解，改善干旱胁迫对苜蓿叶片的非气孔限制，提高SOD、POD、CAT活性，促进ASA-GSH循环，增加渗透调节物质含量，以减少$O^{\bar{.}}_{2}$和H₂O₂的产生，降低膜脂过氧化程度，从而增加干旱胁迫下陇中苜蓿的株高和叶片RWC，进而增强其抗旱性。外施0.5 mmol·L^-1 Spm是提高干旱胁迫下紫花苜蓿抗旱性的有效方法，可将其应用于提高旱区紫花苜蓿抗旱性的实际生产中。

关键词: 紫花苜蓿, 干旱胁迫, 外源精胺, 抗旱性, 生理

Abstract:

【Objective】Spermine (Spm) can improve the tolerance of plants to abiotic stresses and reduce the damage caused by abiotic stresses to plants. To investigate the effect of exogenous Spm on drought resistance of alfalfa under drought stress, to provide a theoretical basis for exogenous Spm to improve drought resistance of alfalfa, and then to provide a scientific basis for the application of utilizing exogenous Spm to enhance drought resistance of plants. 【Method】Longzhong alfalfa (Medicago sativa L. cv. Longzhong) was used as the experimental material, and polyethylene glycol 6000 was used to simulate drought stress. Under normal water and drought stress after the root application of 0.1, 0.5 and 1.0 mmol·L^-1 concentration of Spm, the change characteristics in Longzhong alfalfa were studied, including plant height, leaf relative water content (RWC), photosynthetic pigments content, gas exchange parameters, antioxidant enzymes activity, antioxidants content, superoxide anion ($O^{\bar{.}}_{2}$) content, hydrogen peroxide (H₂O₂) content, malondialdehyde (MDA) content and osmoregulatory substances content. 【Result】Under drought stress, exogenous Spm increased plant height and leaf RWC of Longzhong alfalfa, slowed down the degradation of chlorophyll a, chlorophyll b (Chlb), and carotenoids, elevated the net photosynthetic rate, transpiration rate, and stomatal conductance of leaves, reduced the concentration of intercellular carbon dioxide, enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), raised the ascorbic acid (ASA) content, ASA/ dehydroascobic acid (DHA) ratio, glutathione (GSH) content and GSH/ glutathione disulfide (GSSG) ratio, decreased DHA and GSSG content, enhanced ascorbate peroxidase and glutathione reductase activities, decreased $O^{\bar{.}}_{2}$ and H₂O₂ production, inhibited MDA accumulation, and increased proline and soluble sugar content. The results of principal component analysis and calculation of average affiliation function values of all physiological indexes under each treatment showed that Spm application under normal water conditions had no effect on the growth of alfalfa, whereas Spm application under drought condition improved the drought tolerance of Longzhong alfalfa under drought stress, with the best enhancement effect of 0.5 mmol·L^-1 Spm. A further redundancy analysis showed that 0.5 mmol·L^-1 Spm enhanced the drought tolerance of Longzhong alfalfa mainly by slowing down the degradation of leaf Chlb, increasing the ASA-GSH cycle and CAT activity.【Conclusion】Exogenous Spm could reduce the degradation of photosynthetic pigments, alleviate the non-stomatal restriction of drought stress on alfalfa leaves, increase the activities of SOD, POD and CAT, promote the ASA-GSH cycle, increase the content of osmoregulatory substances, reduce the production of $O^{\bar{.}}_{2}$ and H₂O₂, and decrease the degree of membrane lipid peroxidation, thus increasing the plant height and leaf RWC of Longzhong alfalfa under drought stress, thereby enhancing its drought resistance. Exogenous application of 0.5 mmol·L^-1 Spm was an effective method to improve the drought resistance of alfalfa under drought stress, and it could be applied to improve the drought resistance of alfalfa in dry areas for practical production.

Key words: alfalfa, drought stress, exogenous spermine, drought tolerance, physiology

王文娟, 师尚礼, 康文娟, 杜媛媛, 殷辰. 干旱胁迫下陇中紫花苜蓿对外源精胺的生理响应[J]. 中国农业科学, 2025, 58(4): 676-691.

WANG WenJuan, SHI ShangLi, KANG WenJuan, DU YuanYuan, YIN Chen. The Physiological Response of Longzhong Alfalfa to Exogenous Spermine Under Drought Stress[J]. Scientia Agricultura Sinica, 2025, 58(4): 676-691.

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https://www.chinaagrisci.com/CN/Y2025/V58/I4/676

图/表 11

表1

试验处理与方法"

处理Treatment	具体方法Concrete method
正常水分+0 Spm Normal water+ 0 Spm	未经Spm预处理的陇中紫花苜蓿在Hoagland营养液中培养 Longzhong alfalfa without Spm pretreatment was cultivated in Hoagland nutrient solution
正常水分+0.1 mmol·L^-1 Spm Normal water + 0.1 mmol·L^-1 Spm	经0.1 mmol·L^-1 Spm预处理的陇中紫花苜蓿在Hoagland营养液中培养 Longzhong alfalfa pretreated with 0.1 mmol·L^-1 Spm was cultivated in Hoagland nutrient solution
正常水分+0.5 mmol·L^-1 Spm Normal water + 0.5 mmol·L^-1 Spm	经0.5 mmol·L^-1 Spm预处理的陇中紫花苜蓿在Hoagland营养液中培养 Longzhong alfalfa pretreated with 0.5 mmol·L^-1 Spm was cultivated in Hoagland nutrient solution
正常水分+1.0 mmol·L^-1 Spm Normal water + 1.0 mmol·L^-1 Spm	经1.0 mmol·L^-1 Spm 预处理的陇中紫花苜蓿在Hoagland营养液中培养 Longzhong alfalfa pretreated with 1.0 mmol·L^-1 Spm was cultivated in Hoagland nutrient solution
干旱+0 Spm Drought+ 0 Spm	未经Spm预处理的陇中紫花苜蓿在含有-1.2 MPa PEG-6000 的营养液中培养 Longzhong alfalfa without Spm pretreatment was cultivated in nutrient solution containing -1.2 MPa PEG-6000
干旱+0.1 mmol·L^-1 Spm Drought+ 0.1 mmol·L^-1 Spm	经0.1 mmol·L^-1 Spm预处理的陇中紫花苜蓿幼苗在含有-1.2 MPa PEG-6000 的营养液中培养 Longzhong alfalfa pretreated with 0.1 mmol·L^-1 Spm was cultivated in nutrient solution containing -1.2 MPa PEG-6000
干旱+0.5 mmol·L^-1 Spm Drought+ 0.5 mmol·L^-1 Spm	经0.5 mmol·L^-1 Spm预处理的陇中紫花苜蓿幼苗在含有-1.2 MPa PEG-6000的营养液中培养 Longzhong alfalfa pretreated with 0.5 mmol·L^-1 Spm was cultivated in nutrient solution containing -1.2 MPa PEG-6000
干旱+1.0 mmol·L^-1 Spm Drought+ 1.0 mmol·L^-1 Spm	经1.0 mmol·L^-1 Spm预处理的陇中紫花苜蓿幼苗在含有-1.2 MPa PEG-6000的营养液中培养 Longzhong alfalfa pretreated with 1.0 mmol·L^-1 Spm was cultivated in nutrient solution containing -1.2 MPa PEG-6000

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处理 Treatment	平均隶属函数值 Average affiliation function values	隶属函数排名 Ranking of affiliation functions
正常水分+0 Spm Normal water +0 Spm	0.49	4
正常水分+0.1 mmol·L^-1 Spm Normal water +0.1 mmol·L^-1 Spm	0.52	3
正常水分+0.5 mmol·L^-1 Spm Normal water +0.5 mmol·L^-1 Spm	0.52	3
正常水分+1.0 mmol·L^-1 Spm Normal water +1.0 mmol·L^-1 Spm	0.52	3
干旱+0 Spm Drought +0 Spm	0.24	6
干旱+0.1 mmol·L^-1 Spm Drought +0.1 mmol·L^-1 Spm	0.47	5
干旱+0.5 mmol·L^-1 Spm Drought +0.5 mmol·L^-1 Spm	0.80	1
干旱+1.0 mmol·L^-1 Spm Drought +1.0 mmol·L^-1 Spm	0.61	2