木薯‘新选048’二倍体及其同源四倍体对干旱胁迫的生理响应

Physiological responses of cassava variety ‘Xinxuan 048’ diploid and autotetraploid to drought stress

为研究不同倍性木薯对干旱胁迫耐受能力的差异,本研究以木薯品种‘新选048’二倍体及其同源四倍体盆栽苗为材料,设置不同程度的干旱胁迫,研究干旱对2个倍性木薯苗形态、渗透调节物质、抗氧化能力及内源激素的影响。结果表明:随着干旱胁迫程度的加强,2个倍性的木薯叶片均出现下垂、萎蔫、变黄,进而干枯的症状,二倍体表现更为严重。可溶性蛋白和脯氨酸(Pro)含量基本随着胁迫程度的加剧而逐渐增加,二倍体更为敏感,积累量大于四倍体。2个倍性材料的抗氧化相关指标基本随着干旱程度的加强而升高,四倍体总抗氧化能力(T-AOC)和超氧化物歧化酶(SOD)活性比二倍体高,而过氧化氢(H_2O_2)含量、丙二醛(MDA)含量、过氧化物酶(POD)活性和过氧化氢酶(CAT)活性比二倍体低。随着干旱程度的增加,2个倍性材料的赤霉素(GA)含量先上升后下降,在四倍体中的含量始终大于二倍体;吲哚乙酸(IAA)含量变化不规则;玉米素核苷(ZR)含量在二倍体中逐渐下降,而在四倍体中先轻微上升后下降,在四倍体中下降幅度较大,但ZR含量在四倍体中始终大于二倍体中的含量;脱落酸(ABA)含量先上升后下降,轻度胁迫下四倍体大于二倍体,其他程度胁迫下二倍体大于四倍体。综合分析,在干旱胁迫下,四倍体木薯产生较强的抗氧化能力,同时通过GA、ZR和ABA的协同作用,延长叶片的功能期,从而达到比二倍体抗旱的效果。

In order to analyse the different response to drought tolerance of cassava（Manihot esculenta） variety ‘Xinxuan 048＇ diploid and autotetraploid,we set up different treatments of drought stress to measure the morphology,osmotic adjustment indexes,antioxidant capacity and endogenous hormones of cassava diploid and its autotetraploid seedlings.The results showed that,with the increase of drought stress,leaves of the two genotype cassava appeared drooping,wilting,yellowing and withering,and the performance of diploid plant was more serious.Both of the contents of soluble protein and proline（Pro） of the two genotypes increased gradually with the increase of drought stress.The diploid was more sensitive,and accumulated more soluble protein and proline than the autotetraploid.The antioxidant indexes of the two genotype cassava increased with the strengthening of drought stress.The autotetraploid plant had stronger total antioxidant capacity（T-AOC） and higher superoxide dismutase（SOD） activity,but lower hydrogen peroxide（H2O2） content,malondialdehyde（MDA） content,peroxidase（POD） activity and catalase（CAT） activity compared with the diploid.With the increase of drought stress,the gibberellin（GA） contents in the two genotype cassava increased firstly and then drop.the GA content in autotetraploid plant was higher than that in the diploid.The indole acetic acid（IAA） contents of the two genotypes changed irregularity.The content of atin riboside（ZR） gradually declined in the diploid plant,but slightly increased firstly and then decreased quickly in autotetraploid,the ZR content in autotetraploid was always higher than that in diploid.It was observed that the content of abscisic acid（ABA） increased firstly and then decreased in both of the two genotype cassava,the autotetraploid ABA content under mild stress was great than that in diploid,but the other degree under stress was opposite.Comprehensive analysis showed that the autotetraploid cassava had strong antioxidant capacity under drought stress.Meanwhile,the synergistic effect of GA,ZR and ABA prolonged the functional period of leaves,so as to get higher drought resistance than diploid.