不同供磷水平对小麦苗期干旱胁迫适应性的影响

Effects of Phosphorus Supply Level on Drought Stress Adaptability of Wheat at Seedling Stage

为探讨不同磷供应水平下小麦应对干旱胁迫的适应性机制,选用新疆冬小麦主栽品种新冬20号为供试材料,在正常磷(CP:1.0 mmol·L^(-1))和低磷(LP:0.05 mmol·L^(-1))两种水平下进行水培试验,并施加15%聚乙二醇-6000(PEG-6000)模拟干旱胁迫,分别测定干旱胁迫0、3、5、7 d及复水3 d的幼苗相关生理生化指标、干旱7 d及复水3 d的离子组变化,并通过芯片检测干旱7 d后根系中相关基因表达水平。结果表明,与CP相比,LP对小麦植株干重产生抑制作用,且对地上部的影响大于根系;LP对总根长、总根表面积和总根体积有较好的促进作用。干旱胁迫后LP对根系相关生长指标的影响表现为先抑后促;复水后LP下植株的恢复能力更强。LP对根系丙二醛(MDA)、植株可溶性糖和含水量也有抑制作用;但干旱胁迫后,与同时期CP相比,LP对小麦地上部MDA含量、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性和含水量以及根系POD活性均有促进作用。与CP相比,LP处理中根系和地上部矿质元素含量均大部分下降。通过芯片检测,干旱胁迫7 d后,与CP相比,LP下根系中硅转运蛋白基因和硫转运相关基因显著上调,抗逆相关基因极显著上调,相关热激蛋白编码基因均极显著下调。综上所述,低磷环境下小麦根系的觅养行为通过调节生理过程、离子和基因水平得到一定程度的补偿,对干旱胁迫有一定的耐受性,对干旱胁迫的适应性增强,有助于复水后较快恢复。

In order to explore the effect of phosphorus apply on the adaptability of wheat under drought stress, a Xinjiang winter wheat variety Xindong 20 was selected as the test material.The hydroponic experiments were carried out at normal phosphorus(CP:1.0 mmol·L^(-1)) and low phosphorus(LP: 0.05 mmol·L^(-1)) levels, and then the drought stress simulated by 15% polyethylene glycol(PEG-6000) was subjected to wheat plant.The changes of physiological indices, ion groups, and the expression of the related genes in seedlings were analyzed at the respective sampling period. The results showed that LP treatment inhibited the dry weight of wheat plant compared with CP treatment.Moreover, the effect on the shoot is greater than that on the root. The total root length, root surface area and the root volume were promoted by LP treatment. The effect of LP on root growth index was first inhibited and then promoted under drought stress.The ability of plant recovery was stronger under LP after rewatering compared with CP treatment. The contents of malondialdehyde(MDA), soluble sugar and water in roots were inhibited by LP. However, compared with CP at the same time, LP promoted MDA content, peroxidase activity, superoxide dismutase activity, and water content in shoot, and POD in root of wheat after drought stress. Compared with CP, the content of mineral elements in root and shoot decreased largely under LP treatment. Compared with CP, silicon transporter gene, sulfur transporter-related gene, and the stress resistant-genes were significantly up-regulated, and the genes encoding heat shock proteins were significantly down-regulated in LP root under drought stress for 7 d. In summary, the foraging behavior of wheat roots under low phosphorus environment was compensated by adjusting physiological process, ion and gene level to some extent.The compensation effect makes wheat plants have certain drought tolerance. Thus, the adaptability to drought stress is enhanced, which is helpful to recover more quickly after rewatering.