生长素对铝胁迫下不同耐铝性小麦根苹果酸分泌的影响

Effect of Auxin on Al-Induced Malic Acid Efflux in Wheat with Differential Al Tolerance

【目的】研究Indole-3-acetic acid(IAA)对铝胁迫下小麦根苹果酸分泌的影响,探讨不同耐铝性小麦品种间苹果酸分泌差异机理。【方法】采用溶液培养的方法,以不同耐铝性小麦品种为材料(ET8,耐铝型和ES8,铝敏感型),研究IAA、N-1-napthyl-phtalamic acid(NPA)、2,3,5-triiodobenzoic(TIBA)、Anthracene-9-carboxylic acid(A9C)及Niflumic acid(NIF)对ET8和ES8苹果酸分泌的影响。【结果】ET8和ES8经不同浓度IAA(0、25、50和100μmol·L-1)处理,苹果酸分泌速率均无显著差异;而当ET8和ES8经50μmol·L-1Al处理3h后,无铝条件下,再经不同浓度IAA处理,ET8苹果酸分泌速率随IAA浓度的升高而显著升高,ES8苹果酸分泌速率却无显著变化;与Al(50μmol·L-1)处理相比,ET8经IAA(50、100μmol·L-1)和50μmol·L-1Al共处理,苹果酸分泌速率显著升高,但ES8经IAA(25、50μmol·L-1)和50μmol·L-1Al共处理,苹果酸分泌速率均无显著变化;与Al(50μmol·L-1)处理相比,ET8和ES8经IAA转运抑制剂NPA(TIBA)和Al(50μmol·L-1)共处理,苹果酸分泌速率显著降低,以上结果表明,IAA参与调节铝胁迫下苹果酸分泌。与Al(50μmol·L-1)处理相比,ET8和ES8经5μmol·L-1A9C(NIF)和Al(50μmol·L-1)共处理,苹果酸分泌显著降低;与5μmol·L-1A9C(NIF)和Al(50μmol·L-1)共处理相比,ET8和ES8经不同浓度IAA、5μmol·L-1A9C(NIF)和Al(50μmol·L-1)共处理,苹果酸分泌速率随IAA浓度升高而显著升高,表明IAA可能通过调节阴离子通道参与铝胁迫下小麦根苹果酸分泌。【结论】只有在Al激活苹果酸分泌后,IAA才能增加耐铝型小麦品种分泌苹果酸,不同耐铝性小麦品种苹果酸分泌的显著差异与IAA对不同耐铝性小麦品种苹果酸分泌调节作用的差异有关。

【Objective】 The effects of indole-3-acetic acid （IAA） on malic acid secretion in wheat roots were studied under Al stress. The mechanism of malic acid secretion difference of different Al-tolerant wheat varieties was investigated. 【Method】 Hydroponic experiments were performed by two wheat （Tritium aestivum L.） cultivars,ET8 （Al-resistant） and ES8 （Al-sensitive）. The effects of exogenous IAA,N-1-napthyl-phtalamic acid （NPA）,2,3,5-triiodobenzoic （TIBA）,anthracene-9-carboxylic acid （A9C）and niflumic acid （NIF） on secretion rate of malic acid were investigated. 【Result】 Effects of different concentrations of IAA （0,25,50,and 100 μmol·L^-1） treatments on the secretion of malic acid were not observed in both ET8 and ES8. After a pretreatment with 50 μmol·L-1 Al for 3 h,different concentrations of IAA were applied at the Al free condition for 24 h,the secretion of malic acid increased significantly with the increasing concentrations of IAA in the ET8 but not ES8. Compared to Al （50 μmol·L^-1） treatments,the secretion of malic acid in ET8 increased significantly under the co-treatment of IAA （50,100 μmol·L-1） and Al （50 μmol·L-1）,but no significant changes were seen in ES8 under the co-treatments of IAA （25,50 μmol·L^-1） and Al （50 μmol·L^-1）. Compared to Al （50μmol·L^-1） treatments,the secretion rate of malic acid in ET8 and ES8 decreased under the co-treatments of IAA transport inhibitors NAP （TIBA） and Al （50 μmol·L^-1）. Results above suggested that IAA involved in the Al-induced malic acid secretion. Compared to Al （50 μmol·L^-1） treatments,significant decrease of malic acid secretion rate were observed in ET8 and ES8 under the co-treatments of 5 μmol·L^-1 A9C （NIF） and Al （50 μmol·L^-1）. Compared to the co-treatments of A9C （NIF） and Al （50 μmol·L^-1）,significant increase of malic acid secretion rate were observed in ET8 and ES8 under the co-treatments of different concentrations of IAA,5 μmol·L^-1 A9C （NIF） and Al （50 μmol·L^-1）. Results above suggested that IAA may regulate Al-induced malic acid secretion of wheat roots via anion channel. 【Conclusion】 On the condition that malic acid secretion pathway was activated by Al,the secretion of malic acid could be increased by IAA. The different regulation effects of IAA on the secretion of malic acid of wheat with different Al-tolerant levels related with the difference of malic acid secretion.