As(Ⅲ)胁迫对小麦发芽过程中木聚糖酶活性及基因表达动态变化的影响

Effect of As(Ⅲ) stress on the xylanase activity and its gene expression during wheat germination

采用室内水培方法,研究了不同浓度As(Ⅲ)胁迫对小麦发芽过程中籽粒、幼根、幼叶3个部位在培养180h内木聚糖酶活性的动态变化。并以小麦稳定表达的肌动蛋白基因作为对照,利用半定量RT-PCR技术,对小麦木聚糖酶基因的表达进行了研究。结果表明,小麦发芽过程中3个部位木聚糖酶活性平均值大小顺序为籽粒>幼芽>幼根。随着As(Ⅲ)浓度升高,籽粒中木聚糖酶活性呈现低促高抑的趋势,幼根和幼叶中木聚糖酶活性呈上升趋势。4个浓度As(Ⅲ)处理后木聚糖酶基因表达强度依次为25mg/L>5mg/L>0mg/L>0.1mg/L。

The dynamic changes of xylanase activity in seed, root and plumule of wheat treated by different As（Ⅲ） concentrations were studied using the water cultivating method. The results indicated that the average xylanase activity was higher in seed than in plumule and root. With the increased As（Ⅲ） concentration, the xylanase activity first went up then went down in seed, while it presented a asending trend in root and plumule. As the sampling time prolonged, the xylanase activity in seeds first rose then dropped with the treatment of As（Ⅲ）, the enzyme activity on 0mg/L and 0. lmg/L As（Ⅲ） concentrations appeared a peak at 60h and 120h, the zenith of 5 mg/L As（Ⅲ） concentration appeared at 72h and 120h, and it came forth at 72h and 108h on 25mg/L As（Ⅲ） stress. The xylanase activity on 0.1,5, 25mg/L As（Ⅲ） concentration first ascended then descended in roots, they all appeared peaks at 60h, but the activity presented a descendant trend with 0mg/L As（Ⅲ） treatment during the germination. As sampling time prolonged, the xylanase activity first elevated then dropped along in plumule on As（Ⅲ） stress. The enzyme activity was moving up as the As（Ⅲ） concentration went up. Overall, It had a strong inhibition to xylanase activity in seeds as well as a strongly stimulative effect in roots on 25mg/L As（Ⅲ） stress. Semi-quantity Reverse Transcription Polymerase Chain Reaction was used to study the xylanase gene expression. The results showed that, the xylanase gene began to express at 132h on 0mg/L As（Ⅲ） stress in wheat leaves, but its expression phase was short, there was no expression after the 8th day of germination. At the same time, The xylanase gene began to express at 120h on the other As（Ⅲ） concentrations. In addition, the xylanase gene expression was enhanced when the wheat was treated in 25mg/L As（Ⅲ） concentration.