2,4-表芸苔素内酯浸种对干旱胁迫下大麦种子萌发期淀粉代谢的影响

Effects of soaking seeds with 2,4-epbrassinolide on starch netabolism during germination of barley seeds under drought stress

为研究2,4-表芸苔素内酯对干旱胁迫下大麦种子萌发期淀粉代谢的影响,将新啤6号大麦种子用不同浓度芸苔素内酯浸种处理,在质量分数23%聚乙二醇-6000溶液中进行培养。在种子萌发72 h时,统计发芽率和幼苗生长指标,并在12、24、36、48、60、72 h测定种子的淀粉酶活性和淀粉、可溶性总糖、蔗糖、果糖、葡萄糖含量。结果表明:干旱胁迫会显著抑制种子萌发,也会降低萌发过程中的淀粉酶活性,提高淀粉含量,降低可溶性糖含量;与单独干旱胁迫相比,适宜浓度(5、25μg·L^(-1))的芸苔素内酯可显著提高种子的发芽率、根长、芽长和胚芽鞘长,使萌发种子内的淀粉酶活性不断增强,淀粉含量持续降低。25μg·L^(-1)芸苔素内酯处理的大麦种子可溶性总糖、葡萄糖、蔗糖和果糖含量显著提高,而较高浓度(200μg·L^(-1))芸苔素内酯对上述指标表现出抑制作用。综上,适宜浓度的芸苔素内酯可通过提高干旱胁迫下种子的淀粉代谢速率来促进种子萌发和幼苗生长。

To study the effects of 2,4-epbrassinolide on starch metabolism of barley seeds during germination under drought stress,XinPi No.6 barley seeds were soaked in brassinosteroid solution with different concentrations and cultured in 23%polyethylene glycol 6000 solution.The germination rate and seedling growth indexes were measured 72 h after germination,amylase activities and contents of starch,soluble total sugar,sucrose,fructose and glucose in barley seeds were determined at 12,24,36,48,60 and 72 h after germination.The results showed that drought stress significantly inhibited seed germination and amylase activities,increased starch contents and decreased soluble sugar contents.Compared with drought stress alone,application with suitable concentrations of brassinosteroid(5,25μg·L^(-1))significantly increased germination rate,root length,bud length,coleoptile length,increased amylase activities and decreased starch contents in germinated seeds.The contents of soluble total sugar,glucose,sucrose and fructose were significantly increased under 25μg·L^(-1) brassinosteroid treatment,while higher concentration(200μg·L^(-1))inhibited the above indexes.These results suggested that suitable concentrations of brassinosteroid could enhance seed germination and seedling growth through promoting the rate of starch metabolism under drought stress.