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研究报告

The effects of inhibitors on organic acids and activities of metabolism-related enzymes in aluminum-treated roots of rape

摘要：采用水培法,研究两个油菜品种华油2790(铝敏感型)和中双7号(耐铝型),在4个铝浓度(0、50、100、200 μmol·L^-1)和外源抑制剂Mersal (5 μmol·L^-1)复合处理下,根系分泌柠檬酸、苹果酸、总有机酸和4种根系代谢相关酶的活性变化.实验结果显示:短期、低浓度的铝胁迫使油菜根系分泌的柠檬酸、苹果酸、总有机酸含量,以及代谢相关酶活性总体上有所增加,但随着时间的延长和铝浓度的增加,均有所降低.加入Mersal后,与单铝处理相比,柠檬酸含量下降,苹果酸含量增加,柠檬酸合酶(Citrate acid, CS)、苹果酸脱氢酶(Malate dehydrogenase, MDH)、乌头酸酶(Aconitase, ACO)活性下降、磷酸烯醇式丙酮酸羧化酶(Phosphoenolpyruvate carboxylase, PEPCase)活性有所增加.结果证明:抑制剂Mersal加重了铝毒对油菜的伤害,破坏了油菜根系代谢中有机酸对铝毒的缓解机制,且在铝敏感品种华油2790中表现更明显,油菜主要可以通过调节根系分泌物的组分,增加苹果酸等的分泌,调控PEPCase的活性等来应对低浓度,短时间的铝胁迫,随着铝浓度的增加和处理时间的延长,铝毒害进一步加深.

Abstract：Under hydroponic conditions, activities of four metabolism-related enzymes were investigated in roots of two rape cultivars Huayou 2790 (Al-sensitive) and Zhongshuang No.7 (Al-resistant), treated with different aluminum (Al) concentrations of 0, 50, 100, 200 μmol·L^-1 combined with an inhibitor Mersal (5 μmol·L^-1), respectively. The results showed that the root secretion of citric acid, malic acid, total organic acid and activities of metabolism-related enzymes increased to some extents under short-term and low concentration treatments, but started to gradually decrease with the increased time and Al concentrations. Compared to the Al treatment only, combination treatments with Al and Mersal significantly reduced citric acid content, activities of Citrate acid (CS), Malate dehydrogenase (MDH), and Aconitase (ACO), while enhanced malic acid content, Phosphoenolpyruvate carboxylase (PEPCase) enzyme activity. These results suggested that the inhibitor Mersal aggravated Al toxicity and diminished the role of organic acids in alleviating Al toxicity in the rape cultivars, especially in the sensitive cultivar Huayou 2790. The oil rape can adjust the root exudation, increase the secretion of malic acid, etc., and regulate the PEPCase enzyme activity to respond to low concentrations and short-time Al stress, but with the increase of Al concentrations and treatment time, aluminum toxicity was further deepened.