【作者】 韦进进；

【导师】 黎晓峰；

【作者基本信息】 广西大学 ， 植物营养学， 2006， 硕士

【摘要】 黑麦根系在铝胁迫下能分泌柠檬酸和苹果酸这两种有机酸。本文以水培方法，研究了复合有机酸（柠檬酸-苹果酸）对铝胁迫下5日龄小麦（晋麦47）幼根细胞膜透性、过氧化物酶、过氧化氢酶和H⁺-ATPase活性和根伸长的影响，旨在探讨根系分泌的复合有机酸对铝的解毒机制。研究结果显示：复合有机酸能使50μmol·L^-1铝处理的小麦幼根电解质渗漏率下降，根尖POD、CAT、H⁺-ATPase活性提高，幼根伸长量增加，并且复合有机酸的效果随着浓度(25～200μmol·L^-1)的增加而增强。在50或100μmol·L^-1苹果酸的基础上，柠檬酸—苹果酸比值从1：2增加到1：1后复合有机酸的解毒效果更显著，而在相同柠檬酸浓度下苹果酸浓度增加一倍对小麦铝毒害无显著影响。这些结果表明，黑麦根系分泌柠檬酸和苹果酸可以减轻铝对作物细胞膜、根伸长的毒害，铝诱导黑麦根系分泌的复合有机酸是其抵御铝毒的有效机制。另一方面，为探讨铝胁迫下H⁺-ATPase对黑麦根系分泌复合有机酸的调控作用，本文以5日苗龄的黑麦（King）、小麦（晋麦47）为材料，研究了激素（IAA、ABA）、阴离子通道抑制剂（NIF、9-AC、DIDS）及质膜ATPase抑制剂（SV）对根尖H⁺-ATPase活性及根系分泌有机酸的影响。研究结果显示，10、30、50μmol·L^-1Al³⁺处理24h后耐铝的黑麦根尖H⁺-ATPase活性均高于铝敏感的小麦。在铝胁迫下H⁺-ATPase受低浓度的IAA(1μmol·L^-1)处理所激活，而根系分泌的有机酸随着H⁺-ATPase的激活而增加。相反，当H⁺-ATPase的活性因ABA(1、25μmol·L^-1)、高浓度IAA(25μmol·L^-1)处理而降低后，有机酸的分泌受到显著的抑制。1μmol·L^-1IAA对黑麦根尖H⁺-ATPase活性起促进作用，而1μmol·L^-1ABA抑制H⁺-ATPase活性。这些结果说明，根尖H⁺-ATPase可能参与铝诱导黑麦根系分泌有机酸的调控。另一方面，在1μmol·L^-1IAA溶液中，10μmol·L^-1阴离子通道抑制剂NIF、9-AC、DIDS对黑麦根尖H⁺-ATPase活性及铝诱导根系分泌有机酸均有抑制效应。并且，NIF、9-AC、DIDS处理加强1μmol·L^-1ABA对根尖H⁺-ATPase活性和铝诱导黑麦根系分泌有机酸的抑制。这些结果说明，H⁺-ATPase对黑麦根系分泌有机酸分泌的影响可能通过阴离子通道介导。此外，质膜H⁺-ATPase专性抑制剂SV对黑麦根尖H⁺-ATPase活性及铝诱导有机酸的分泌有显著抑制作用，这暗示着黑麦根尖质膜H⁺-ATPase是根尖细胞中调节有机酸分泌的重要因子。更多还原

【Abstract】 The secretion of citrate and malate from rye roots could be induced by Al stress. In order to elucidate the Al detoxification mechanisms by compound organic acids （citrate and malate） in rye, five-day-old Al-sensitive wheat（ Jin mai 47） roots were objected to study the effects of these organic acids on root elongation, root cell membrane osmosis, activities of catalase （CAT）, peroxidase （POD） and H⁺-ATPase of root apices by water-cultivated method. It showed that Al induced increasing in electrolyte of roots was suppressed by the addition of both citrate and malate, while an increase in both root elongation and activities of CAT, POD and H⁺-ATPase were found in the treatments with both citrate and malate under 50μmol·L^-1 Al stress. These effects of compound organic acids were increased with the increasing of their dose (25～200μmol·L^-1) . Al-detoxification effect of compound organic acids was more significant as the increasing rate of citrate/malate from 1:2 to 1:1 in the certain concentration of malate (50, 100μmol·L^-1). However, there had no distinct Al-detoxifcation effect of compound organic acids on wheat with doubled the concentration of malate in the certain concentration of citrate. These results indicated that Al-induced secretion of both citrate and malate was an effective mechanism for rye to deal with Al toxicity and Al-induced secretion of compound organic acids was an Al resistant mechanism for rye.On the other hand, in order to investigate the regulation of H⁺-ATPase on Al-induced secretion of organic acids from rye roots, five-day-old rye（King） and wheat（Jin mai 47） roots were objected to study the relationship between H⁺-ATPase and the secretion of organic acids by treating with abscisic acid （ABA） and indoleacetic acid （IAA）, anion inhibitors 4,4’-diisothio-cyanostilbene-2,2’-disuifonic acid （DIDS）, niflumic acid （NIF）, anthracene-9-carboxylic acid （9-AC） and plasma membrane ATPase inhibitor （SV）. These results showed that H⁺-ATPase activity of rye root apices was higher than that in wheat after exposure of roots to 10、30、50μmol·L^-1 AI solution for 24 h. Under Al stress, H⁺-ATPase activity was stimulated by low concentration IAA (1μmol·L^-1) treated, while the secretion of organic acids was increased. However, H⁺-ATPase activity was significantly inhibited by ABA (1、25μmol·L^-1) and high concentration IAA (25μmol·L^-1), while the amount of Al-induced organic acids was decreasing. Oneμmol·L^-1 IAA and 1μmol·L^-1ABA respectively exerted stimulatory and inhibitory effects on the H⁺-ATPase activities and secretion of organic acids. These results suggested that H⁺-ATPase of root apices would involve in the regulation of Al-induced secretion of organic acids from rye roots.In addition, H⁺-ATPase activity and the secretion of organic acids were inhibited by treatments with 10μmol·L^-1 NIF, 9-AC, DIDS solution which contained 1μmol·L^-1 IAA. Moreover, the inhibitory effect of 1μmol·L^-1ABA on the activity of root apices H⁺-ATPase and Al-induced secretion of organic acids from rye roots was strengthened by NIF, 9-AC and DIDS. These results implied that H⁺-ATPase seemed to involve in activating anion channels to allow organic acids efflux.Furthermore, the secretion of organic acids and H⁺-ATPase activity were inhibited by SV, which is a plasma membrane ATPase inhibitor. It suggested that plasma membrane H⁺-ATPase would be an important regulated factor of cells in Al-induced secretion of organic acids.更多还原