谷子对干旱胁迫的生理生态响应

Abstract

干旱少雨严重限制了我国西北地区谷子的产量，为明确谷子响应干旱的生理特征，以干旱敏感谷子品种安04和不敏感品种豫谷1号以及xiaomi为材料，通过盆栽试验，研究了谷子不同生育期叶片光合参数、叶绿素含量、非结构性碳、β-淀粉酶基因表达对水分亏缺的响应。结果表明，正常水分条件下安04产量高于豫谷1号，干旱胁迫严重限制了两个谷子品种的产量形成，安04和豫谷1号分别减产71.2%和56.0%，豫谷1号产量显著高于安04。正常水分条件下，安04具有比豫谷1号更高的净光合速率（P<0.05），干旱胁迫下，豫谷1号叶片净光合速率显著高于安04；叶片蒸腾速率结果同光合结果一致。干旱条件下，豫谷1号具有更高的叶片相对含水量。干旱胁迫显著降低了两个谷子品种花期的叶绿素a、叶绿素b及总叶绿素含量，且安04降低幅度均大于豫谷1号。干旱胁迫均显著增加了豫谷1号拔节期和开花期的叶片可溶性糖含量，而安04叶片可溶性糖含量并没有发生显著性变化，同时干旱胁迫显著增加了豫谷1号β-淀粉酶基因SiBAM1的表达水平。施用β-淀粉酶活性抑制剂α-环糊精，xiaomi叶片可溶性糖及脯氨酸含量显著降低，进一步加重了干旱对xiaomi的生长抑制。综上所述，干旱胁迫诱导谷子β-淀粉酶基因表达和β-淀粉酶活性升高从而水解淀粉形成可溶性糖，高可溶性糖含量对谷子提高抗旱性起重要作用。;Foxtail millet (Setaria italica L.) is an important commercial crop in north China, especially northwest China. However, the uneven distribution of precipitation induce severe seasonal drought and drought seriously limits the yield production of foxtail millet. To clarify physiological characteristics of different genotypes of foxtail millet cultivars in response to drought stress, drought resistance cultivar (Yugu 1) and drought sensitive cultivar (An 04) and xiaomi were selected as materials to detect and compare the photosynthetic parameters, chlorophyll content, non-structure carbohydrate, gene expression of beta-amylase (SiBAM1) at one or three growth periods (jointing, anthesis and ten days after anthesis stage) through a pot experiment carried out in the rainproof shed. Results showed that under normal soil water condition, the An 04 held higher grain yield than Yugu1 cultivar. Drought stress severely restricted the yield formation of two cultivars. while the yield of An 04 was reduced by 71.2%, and that of Yugu 1 was reduced by 56.0%. And Yugu1 cultivar had higher grain yield that An 04 under drought condition. Under normal soil water conditions, An 04 had a higher net photosynthetic rate than Yugu 1 (P<0.05). while under drought stress, the leaf net photosynthetic rate of Yugu 1 was significantly higher than that of An 04 at these three detected growth stages. Leaf transpiration rate was consistent with that of leaf photosynthetic rate. However, the Yugu1 held higher leaf relative water content than An 04 under drought condition. Drought stress significantly reduced the chlorophyll a, chlorophyll b and total chlorophyll contents of the two cultivars, while the decrease range of An 04 was greater than that of Yugu 1 especially at anthesis stage. Drought stress significantly increased the soluble sugar content in Yugu 1 leaves at the stage of jointing and anthesis stage, while there was no significant change in the soluble sugar content in the leaves of An 04. Drought stress significantly increased the expression level of SiBAM1 in Yugu 1 gene. Application of α-cyclodextrin, an inhibitor of β-amylase activity, further increased the inhibition of drought on the growth of millet xiaomi, and the contents of leaf soluble sugar and proline decreased significantly compared with none α-cyclodextrin application. In summary, drought stress induced the increase of β-amylase gene expression and β-amylase activity in foxtail millet, which could take part in hydrolyzing starch into soluble sugar, and the increased soluble sugar played an important role in improving drought resistance of foxtail millet.