α-亚麻酸对干旱胁迫下水稻种子萌发的影响

Effects of α-linolenic acid on germination of rice seeds under drought stress

亚麻酸属ω-3系统的多不饱和脂肪酸,是细胞膜的重要组成部分。在干旱胁迫下,植物通过释放α-亚麻酸重塑细胞膜的流动性,但外源添加α-亚麻酸能否提高植物对干旱的抗性尚未可知。该研究采用PEG6000模拟干旱胁迫,探讨了种子萌发过程中α-亚麻酸对水稻萌发和幼苗生长过程中抗旱性的影响。结果表明:在14%和16%PEG干旱胁迫下,水稻种子推迟萌发,幼苗的生长受到抑制。25μmol·L^(-1)和250μmol·L^(-1)的α-亚麻酸可缓解干旱对水稻幼根和幼苗生长的抑制,且随着干旱程度的增加,缓解作用增强。16%PEG胁迫下,25μmol·L^(-1)、250μmol·L^(-1)的α-亚麻酸分别提高幼苗的根长34.3%和29.1%、苗长67.8%和52.0%、根重43.9%和35.2%、苗重59.1%和43.6%。α-淀粉酶活力测定发现,25μmol·L^(-1)和250μmol·L^(-1)的α-亚麻酸分别提高干旱胁迫下水稻种子α-淀粉酶活力为56.7%~70.7%和36.8%~43.8%。水稻幼根活力测定显示,25μmol·L^(-1)和250μmol·L^(-1)的α-亚麻酸分别提高干旱胁迫下幼根活力为11.4%~28.4%和5.4%~22.2%。此外,还对不同干旱胁迫下水稻种子α-淀粉酶活性和幼根活力的变化进行了讨论,认为α-亚麻酸主要通过提高种子萌发过程中α-淀粉酶的活性来缓解所遭遇的干旱胁迫,而对水稻幼根活力的影响则相对有限。

As a member ofω-3 polyunsaturated fatty acids,α-linolenic acid（ALA）is a component of plant cell membrane.It was shown that plants release ALA to remodel the mobility of cell membrane under drought stress.However,it is not known whether exogenous ALA can increase the plant tolerance to drought stress.In this research,we studied the impact of additional ALA on the drought tolerance of rice seeds under PEG6000 during the germination and seedling stage.The result showed that under 14%and 16%PEG stresses,the germination of rice seeds was postponed and their seedlings growth were inhibited.After addition of 25μmol·L^（-1）or 250μmol·L^（-1）of ALA,the inhibiting effect owing to the drought stress was relieved.And the alleviatng effect became stronger as the stress became severer.Under drought stress with 16%PEG,25μmol·L^（-1）and 250μmol·L^（-1）of ALA improved the root length by 34.3%and 29.1%,respectively,while improved the seedling length by 67.8%and 52.0%;the root weight was increased by 43.9%and 35.2%,and the seedling weight was increased by 59.1%and 43.6%,respectively.Analysis ofα-amylase activity in rice grains under 14%and 16%PEG stress showed,after addition of 25μmol·L^（-1）and 250μmol·L^（-1）ALA,the activity was increased by 56.7%-70.7%and 36.8%-43.8%,respectively.Analysis of root activity showed that after addition of 25μmol·L^（-1）and 250μmol·L^（-1）of ALA,the root activity under 14%and 16%PEG stresses were increased by 11.4%-28.4%and 5.4%-22.2%,respectively.The change ofα-amylase activity and root activity with different PEG concentrations were also discussed.Therefore,we propose that ALA can relieve the drought tolerance of rice seeds mainly by means of increasingα-amylase activity during seed germination and seedling growth stages,while with a limited effect on root activity of rice radicle.