Effects of foliar application of organic acids on alleviation of aluminum toxicity in alfalfa
Effects of foliar application of organic acids on alleviation of aluminum toxicity in alfalfa
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DOI：
10.1002/jpln.201200445
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发表时间：
2014-06-01
影响因子：
2.5
通讯作者：
Shi, Dongyan
中科院分区：
文献类型：
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作者：
An, Yuan;Zhou, Peng;Shi, Dongyan
在酸性土壤中，有机酸（OA）会影响植物对铝毒的抗性。然而，有限的资料是不同的有机酸对苜蓿抗铝性的影响。研究了叶面喷施有机酸（琥珀酸、柠檬酸、苹果酸和草酸）对紫花苜蓿（Medicago sativa L.）在艾尔的压力下幼苗生长在pH 4.5的营养液中含有铝在0或100 μ M，并喷洒水或100 μ M的草酸，苹果酸，柠檬酸，或琥珀酸每3天在10天的实验。铝胁迫显著降低了紫花苜蓿的生长（地上生物量、根重和根长）、根系活力、矿质营养元素（Ca、K、Mg、Mn和Zn）含量，并显著增加了叶片膜脂过氧化。叶面施用4种有机酸，特别是琥珀酸，减轻铝毒，表现为植物生长和根系活力的增加，以及减少脂质过氧化作用。草酸和苹果酸处理显著增加了铝胁迫下根系的草酸分泌，降低了铝浓度。琥珀酸处理显著增加了根中4种有机酸的积累，增加了Ca、K、Mg、Mn和Zn的积累，并上调了苹果酸脱氢酶（MDH）和磷酸烯醇式丙酮酸羧化酶（PEPC）基因的转录。结果表明，外源草酸和苹果酸促进了苜蓿根系草酸的分泌，从而提高了苜蓿的抗铝性;外源琥珀酸提高了苜蓿的抗铝性，可能与增加了苜蓿根系内源4种有机酸的积累有关，这可能构成了苜蓿的有机酸解毒系统。
Organic acids (OA) may affect plant resistance to aluminum (Al) toxicity in acidic soils. However, limited information is available on the effects of different organic acids on Al resistance in alfalfa. We investigated the effects of foliar application of organic acids (succinic acid, citric acid, malic acid, and oxalic acid) to alfalfa (Medicago sativa L.) under Al stress. Seedlings were grown in pH 4.5 nutrient solution containing Al at 0 or 100 mu M, and were sprayed with water or 100 mu M of oxalic acid, malic acid, citric acid, or succinic acid every 3 d during a 10 d experiment. Aluminum stress caused significant reduction in alfalfa growth (reflected by above-ground biomass, root weight and root length), root activity, mineral nutrient concentrations (Ca, K, Mg, Mn and Zn), and a significant increase in leaf membrane lipid peroxidation. Foliar application of the four organic acids, especially succinic acid, alleviated Al toxicity, as demonstrated by the increase in plant growth and root activity, as well as reduction in lipid peroxidation. Oxalic acid and malic acid treatments significantly increased oxalate exudation and decreased Al concentration in roots exposed to Al stress. Succinic acid treatment significantly increased accumulation of all four organic acids in roots, accumulation of Ca, K, Mg, Mn and Zn, and up-regulated the gene transcription of malate dehydrogenase (MDH) and phosphoenolpyruvate carboxylase (PEPC) in roots. Our results suggest that the promotion of oxalate exudation from roots through exogenous application of oxalate and malate could contribute to the improvement in Al resistance of alfalfa, and the positive effects of exogenous application of succinate on Al resistance may be associated with the increased endogenous accumulation of all four organic acids in roots, which may constitute an organic-acid detoxification system in alfalfa.