砷胁迫下3-吲哚乙酸对不同砷富集能力植物根系形态和生理的影响

Effects of indole-3-acetic acid on morphologic and physiological characteristics of root systems of plants with different arsenic-accumulating abilities under As stress

采用室内水培法,研究了2 mg·L^(-1)五价砷胁迫下,外源添加不同浓度(0、10、20、40、60 mg·L^(-1))3-吲哚乙酸(IAA)14 d对砷超富集植物大叶井口边草(Pteris cretica var.nervosa)和同属的非超富集植物剑叶凤尾蕨(Pteris ensiformis)株高、生物量、砷含量、根系形态(根长、根尖数、根表面积)、根系活力、根细胞质膜ATPase活性、抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT、过氧化物酶POD)活性以及细胞膜脂过氧化产物丙二醛(MDA)含量的影响,并用逐步回归法分析了根部砷含量与所测定根系形态和生理指标的关系。结果表明:20 mg·L^(-1)IAA处理下,两种植物的生物量与对照相比显著增加,大叶井口边草叶片和叶柄砷含量、根系活力和根细胞质膜ATPase酶活性显著增加,且明显高于剑叶凤尾蕨;20~60 mg·L^(-1)IAA处理下,大叶井口边草根中的CAT、SOD和POD活性显著增加,而剑叶凤尾蕨根中的CAT活性显著降低,SOD活性显著增加,POD活性则无显著变化;20~40 mg·L^(-1)IAA处理下,两种植物根中的MDA含量显著降低,但大叶井口边草显著低于剑叶凤尾蕨。逐步回归分析结果显示,大叶井口边草根中砷含量与根系活力显著正相关,而剑叶凤尾蕨根中砷含量与各变量无关。因此,IAA的添加促使大叶井口边草保持较高的根系活力,进而有助于其超量富集砷。

A hydroponic experiment was conducted to investigate the effects of indole-3-acetic acid（IAA）on growth,root morphology,root activity,root ATPase activity in cytoplasmic membrane,root antioxidative enzymes（superoxide dismutase SOD,catalase CAT and proxidase POD）,malondialdehyde（MDA,a peroxidation product of membrane lipids）content,and As accumulation in plants with different As-accumulating abilities.Arsenic hyperaccumulator（Pteris cretica var.nervosa）and non-hyperaccumulator（Pteris ensiformis）were exposed to 2mg·L^（-1）As（V）and different concentrations of IAA（0,10,20,40,and 60 mg·L^（-1））for 14 d.Results showed that biomass of two plants significantly increased in the presence of 20 mg·L^（-1）IAA,compared with the control.At the 20 mg·L^（-1）IAA treatment,As concentrations in fronds and petioles,root activity,and root ATPase activity in cytoplasmic membrane of P.cretica var.nervosa increased significantly,and were significantly higher than those in P.ensiformis.At 20~60 mg·L^（-1）IAA treatments,the activities of three antioxidative enzymes（CAT,SOD and POD）in roots of P.cretica var.nervosa increased significantly,but the CAT activity decreased and SOD activities increased significantly in roots of P.ensiformis,in comparison with no IAA treatment.The POD activity showed no significant changes in the roots of P.ensiformis.The content of MDA in roots of both plants were significantly decreased by 20 ~40 mg·L^（-1）IAA treatments.However,MDA content in the roots of P.cretica var.nervosa was significantly lower than that of P.ensiformis.Correlation analysis showed that As concentrations in roots of P.cretica var.nervosa were positively related with root activity,whereas no correlation was found between root As concentrations and root parameters in P.ensiformis.Therefore,As hyperaccumulation of P.cretica var.nervosa was attributed to its high root activities.