砷胁迫对小麦萌发过程中戊聚糖含量和木聚糖酶活性的影响

Effect of As (Ⅲ) Stress on Pentosan Content and Xylanase Activity during Seed Germination of Wheat

为探讨重金属砷胁迫下小麦幼苗生长过程中戊聚糖的累积变化规律,本试验采用室内水培方法,研究了不同浓度砷胁迫下小麦籽粒萌发、幼苗生长形态指标及籽粒、根、芽3个部位在培养7 d内戊聚糖含量和木聚糖酶活性的动态变化。结果表明,≤5 mg/L的砷对小麦发芽率、根长、芽长、籽粒重、芽重有促进作用,>5 mg/L的砷抑制小麦生长和发芽;随着砷浓度的升高,籽粒中戊聚糖含量呈先上升后下降的趋势,根和芽中戊聚糖含量呈下降趋势;随着砷浓度的升高,籽粒中木聚糖酶活性仍呈先上升后下降的趋势,根和芽中木聚糖酶活性则呈先下降后上升的趋势。对小麦幼苗3个部位来说,戊聚糖含量平均值大小依次为根>籽粒>芽,木聚糖酶活性平均值大小依次为籽粒>芽>根。说明≤5 mg/L的砷促进籽粒中戊聚糖的积累和木聚糖酶的活性,>5 mg/L的砷则抑制之,>5 mg/L的砷对根和芽中木聚糖酶活性有促进作用。

To explore the dynamic change of pentosan content during wheat germination, the dynamic changes of pentosan content and xylanase activity in wheat seed, root and plumule under different As （Ⅲ） concentration treatments were studied. The results indicated that, while the As （Ⅲ） concentration was less than 5 mg/L, the germination rate, the average root length, plumule length, seed weight and plumule weight increased. However, the growth of wheat was inhibited when the concentration of As（ Ⅲ） was more than 5 mg/L. With the increasing concentration of As（ Ⅲ ）, pentosan content elevated first then dropped in seed, but the pontosan content deareased in root and plumule; and the xylanase activity elevated first then dropped in seed, while the xylanase activity dropped first then rose up in root and plumule. On the other side, as the As（ Ⅲ ） concentration increasing, the content of average pentosan in root was more than that in seed and plumule, and the xylanase activity in different organs was in the order of seed〉plumule〉root, which indicated that low concentration of As（Ⅲ） had a positive effect on the accumulation of pentosan and the increase of xylanase activity, And while concentration of more than 5 mg/L had a negative effects on both of them. At the same time, the xylanase activity in roof and plumule in creased while the As（Ⅲ） concentration was more than 5mg/L.