铝胁迫下高粱BTx623幼苗的形态及生理响应特征

Morphological and physiological responses of sorghum BTx623 seedlings to aluminum toxicity

采用不同浓度铝离子(0,25,50,100μmol·L^(-1),p H=4.5)胁迫处理高粱幼苗,以探究铝胁迫对高粱BTx623幼苗生长发育的影响。结果表明,与对照相比,不同浓度铝处理后,高粱幼苗株高无显著变化,但其根系长度和相对伸长率显著下降;25μmol·L^(-1)铝胁迫下幼苗的鲜重、干重、叶绿素含量和根系脱氢酶活性分别增加了11.4%,50.0%,32.1%和32.5%,而50和100μmol·L^(-1)铝胁迫下幼苗鲜重、干重、叶绿素含量和根系脱氢酶活性均有不同程度的下降。随着铝胁迫程度加大,根尖铝积累量、根系过氧化氢(H_2O_2)和丙二醛(MDA)的含量逐渐增加。25μmol·L^(-1)铝胁迫下根系超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性分别上升了44.5%和33.7%,过氧化物酶(POD)活性变化不显著,而100μmol·L^(-1)铝胁迫下这3种酶活性均显著降低。综上,25μmol·L^(-1)铝胁迫下高粱BTx623幼苗根系抗氧化酶活性增强,对鲜重、干重和叶绿素含量亦具有促进作用,但对根系伸长具有显著抑制作用;而50和100μmol·L^(-1)铝胁迫对高粱BTx623幼苗地上及地下部分均具有较强的抑制作用。

The present study investigated the morphological and physiological responses of sorghum BTx623 seedlings under different aluminum （A1） concentrations （ 0, 25,50 and 100 μmol· L ^- 1, pH = 4. 5 ）. It was shown that compa- ring with the control, A1 stress significantly reduced the root relative growth （RRG） and root length, while the height of seedlings was not significandy influenced. The fresh weight, dry weight, chlorophyll content and root dehydrogen- ase activity of seedlings increased by 11.4% , 50.0% , 32.1% and 32. 5% under 25 μmol· L ^- 1 Al stress, whereas decreased under 50 and 100 μmol· L ^- 1 Al stresses. Al accumulation, H2O2 production and MDA content of the root notably elevated as the increase of Al concentration. Further analysis revealed that the SOD and CAT activities were significantly up-regulated by 44. 5% and 33.7% under 25 μmol· L ^- 1 Al stress, while POD activity was not signifi- cantly affected under A1 stress. However, higher concentration of Al （ 100 μmol· L ^- 1 ） could inhibit the activities of these three anti-oxidant enzymes. In conclusion, 25 μmol· L ^- 1 Al stress induced the up-regulation of anti-oxidant en-zymes to alleviate the oxidative stress and increased the fresh weight, dry weight and chlorophyll content, but inhibi- ted the root elongation of sorghum BTx623 seedlings. However, 50 and 100 μmol· L ^- 1Al stress bad significant inbib- itory effects on both above and underground parts of the seedlings.