IAA与KT对菊芋镉富集和生理响应的影响

Effects of IAA and KT on Cadmium Accumulation and Physiological Response of Helianthus tuberosus L.

为探究吲哚乙酸(indole-3-acetic acid,IAA)和激动素(kinetin,KT)对镉胁迫下菊芋(Helianthus tuberosus L.)生理响应及耐镉性的影响,以耐镉型榆林菊芋和镉敏感型成都菊芋为研究对象,设置CK(空白对照,无Cd)、T1(Cd_(300 mg/kg))、T2(Cd_(300 mg/kg)+IAA_(4 mg/L))、T3(Cd_(300 mg/kg)+KT_(8 mg/L))及T4(Cd_(300 mg/kg)+IAA_(4 mg/L)+KT_(8 mg/L))5个处理组,研究了IAA、KT对镉胁迫下菊芋幼苗生长、抗氧化系统、叶绿素荧光特性及镉富集能力的影响。结果表明:2个产地菊芋T1处理下的株高伸长率、叶面积、根系伸长率及干重较CK组均有所下降;激素喷施后可有效提高叶绿素含量,其中榆林菊芋T4处理最大增幅为162.87%。各组脯氨酸(Pro)含量随处理时间呈上升趋势,2个产地菊芋T4处理的最大增幅分别达223.94%和112.73%;而T4处理MDA降幅大于T2、T3处理。T1处理的抗氧化酶活性总体低于T2~T4处理,各组酶活性随植株生长差距逐渐拉大,共同喷施下3种保护酶活性的增幅较为理想。喷施激素显著提升菊芋的根系活力(p<0.05),榆林菊芋、成都菊芋T4处理的根系活力分别提高39.00%和9.10%。T4处理条件下菊芋茎髓部的气泡数目远大于T1~T3处理,2个产地植株黑色区域分别扩增142.59%,700.00%。植物激素单一或共同喷施均可促进菊芋根、茎、叶器官对镉的吸收,根部镉含量最高,茎次之,各器官的镉富集系数均大于2,转运系数大于1,菊芋T4处理的镉含量大于T1~T3处理。综上所述,4 mg/L IAA、8 mg/L KT主要通过提升抗氧化酶活性和Pro含量,以维持活性氧自由基(ROS)产生与清除的动态平衡,减轻膜脂的过氧化并提高根系活力等途径帮助菊芋有效应对镉胁迫环境并强化其富集能力,这为菊芋在镉污染地区的栽培及植物修复土壤镉污染研究提供理论指导。

In order to explore the regulatory effects of indole-3-acetic acid(IAA)and kinetin(KT)on the physiological response and cadmium(Cd)tolerance of Helianthus tuberosus L.under Cd stress,taking H.tuberosus of Yulin and Chengdu as research objects,five treatment groups were set up,which were CK(no Cd),T1(Cd_(300 mg/kg)),T2(Cd_(300 mg/kg)+IAA_(4 mg/L)),T3(Cd_(300 mg/kg)+KT_(8 mg/L))and T4(Cd_(300 mg/kg)+IAA_(4 mg/L)+KT_(8 mg/L)),respectively,to study the effects of IAA and KT on the growth,antioxidant system,ChlorophyⅡfluorescence properties and Cd accumulation ability of H.tuberosus seedlings under Cd stress.The results showed that the plant height elongation,leaf area,root elongation and dry weight of plants in the T1 group all decreased compared with CK.Spraying hormone could effectively increase chlorophyⅡcontent,and the maximum increase was 162.87%in the T4 group of Yulin H.tuberosus.The proline(Pro)content of each group increased with the treatment time,the maximum increase of H.tuberosu T4 group in two places was 223.94%and 112.73%,respectively,while the decrease of MDA in T4 group was greater than that in T2 and T3.The antioxidant enzyme activity of T1 group was generally lower than that of other groups,and the gap in enzyme activities between groups was gradually widening with the plant growth.The increase ofthe three protective enzyme activities in T4 group was ideal.Hormone spraying significantly improved the root vigor of H.tuberosus(p<0.05),and the H.tuberosus T4 group in two places increased by 39.00%and 9.10%,respectively.In the treatment group of T4,the number of bubbles in the pith of H.tuberosus stem was much larger than that of T1 to T3,and the black area of plants from the two producing areas increased by 142.59%and 700.00%,respectively.Single or combined spraying of plant hormones could promote absorption of Cd in the root,stem and leaf organs of H.tuberosus,the content of Cd in root was the highest,followed by the stem.The Cd enrichment coefficient of each organ was all greater than 2,and transport coefficient was greater than 1.The Cd content of H.tuberosus T4 group was greater than T1 to T3.In summary,4 mg/L IAA and 8 mg/L KT could help H.tuberosus effectively respond to the Cd stress environment and strengthen its accumulation capacity by increasing the antioxidant enzyme activity and Pro content,so as to maintain the dynamic balance of reactive oxygen species(ROS)production and removal,reduce membrane lipid peroxidation,and improve root vitality.The results could provide theoretical guidance for the cultivation of H.tuberosus in Cd-polluted areas and phytore mediation of soil Cd pollution.