干旱胁迫对不同根型苜蓿内源激素含量的影响

Effects of drought stress on endogenous hormone contents of different root-type alfalfa

为探究不同根型苜蓿在不同生长年限的抗旱性与内源激素间的关系,采用高效液相色谱法测定根茎型、直根型、根蘖型苜蓿播种当年及生长第2年在干旱胁迫后地上与地下部内源激素吲哚乙酸(IAA)、赤霉素(GA_(3))、玉米素(ZT)和脱落酸(ABA)含量。结果表明,随干旱胁迫加剧,播种当年及生长第2年,根茎型、直根型和根蘖型苜蓿地上、地下部IAA和ZT含量显著降低,相比CK,IAA的年均降幅分别为50.09%、36.52%、49.15%和58.17%、53.42%、56.62%,ZT的年均降幅分别为38.11%、52.57%、36.18%和43.86%、63.94%、54.17%。ABA含量显著升高,随生长年限延长增幅降低,种植当年及生长第2年的增幅分别处于62.50%~358.82%和19.70%~85.19%之间;而GA_(3)含量在播种当年显著下降,生长第2年中、重度胁迫下达到峰值。相比CK,播种当年地上、地下部GA_(3)/ABA、IAA/ABA、(IAA+GA_(3)+ZT)/ABA比值及干质量随胁迫加剧呈下降趋势;生长第2年地上、地下部IAA/ABA比值显著降低,降幅分别为68.63%~70.69%和76.77%~88.65%;GA_(3)/ABA和(IAA+GA_(3)+ZT)/ABA比值先升高后降低;同一干旱胁迫下,地上、地下部GA_(3)、IAA和IAA+GA_(3)+ZT 3组激素与ABA的比值基本表现为根茎型苜蓿最低、直根型苜蓿最高。地上部干质量与叶茎GA_(3)、IAA和ZT含量呈正相关,与ABA含量呈负相关;地下部干质量与根系GA_(3)、IAA和ZT含量呈正相关,与ABA含量呈负相关。可知,根茎型和根蘖型苜蓿在应对干旱胁迫时有较好的适应能力。

The indole acetic acid(IAA),gibberellin A_(3)(GA_(3)),zeatin(ZT)and abscisic acid(ABA)contents in rhizomatous rooted,tap rooted,and creeping rooted alfalfa on the aboveground and underground after drought stress were determined by the method of high-performance liquid chromatography(HPLC)in the current and following years.The relationship between these endogenous hormones and drought resistance of different root-type alfalfa was studied.The results showed that with the intensification of drought stress,the aboveground and underground IAA and ZT contents of rhizomatous rooted,tap rooted and creeping rooted alfalfa decreased significantly during the sowing year and the following growth year.Compared with CK,the annual average decrease of IAA was 50.09%,36.52%,49.15%and 58.17%,53.42%,56.62%respectively,and the decrease of ZT was 38.11%,52.57%,36.18%and 43.86%,63.94%,54.17%respectively.The content of ABA increased significantly,but the rate of increase was gradually declined with the extension of growth years.The increase rates in the sowing year and the following year were 62.50%~358.82%and 19.70%~85.19%respectively.However,GA_(3) contents remarkedly decreased during the sowing year,whereas GA_(3) contents reached the highest level under the moderate and severe stress during the following year.The GA_(3)/ABA,IAA/ABA,(IAA+GA_(3)+ZT)/ABA,and aboveground and underground dry mass decreased under drought conditions during the sowing year.The aboveground and underground IAA/ABA significantly decreased by 68.63%~70.69%and 76.77%~88.65%respectively,and GA_(3)/ABA and(IAA+GA_(3)+ZT)/ABA increased first and then decreased during the following next year.The GA_(3)/ABA,IAA/ABA,and(IAA+GA_(3)+ZT)/ABA were lowest in rhizomatous rooted alfalfa and were highest in tap rooted alfalfa under the same drought stress.There were positive correlations between dry weight of aboveground part and GA_(3),IAA,and ZT contents in leaves and stems as well as between dry weight of underground part and GA_(3),IAA,and ZT contents in roots while ABA content in leaves and stems and in roots was negatively correlated with dry weight of aboveground part and underground part,respectively.Therefore,rhizomatous rooted and creeping rooted alfalfa had better adaptability to drought stress.