铝胁迫对不同耐铝性小麦基因型根尖抗氧化酶活性的影响

Effects of aluminum stress on antioxidant enzyme activity in root tips of wheat genotypes differing in aluminum tolerance

以2个小麦基因型鉴-864(耐性)和扬麦5号(敏感)为材料,在水培条件下研究铝胁迫下根系伸长,根尖铝含量,根尖超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性,丙二醛(MDA)和根尖过氧化氢含量随着时间的变化.结果表明:在30μmol?L-1AlCl3胁迫下,随着铝处理时间的增加,小麦根系伸长受到显著抑制,且扬麦5号受抑制程度更为明显.根尖铝含量随着铝处理时间的增加而上升,且扬麦5号显著高于鉴-864.在铝胁迫下,2个小麦基因型根尖SOD、CAT和APX活性随着处理时间的延长而增加.在铝处理3h时,2个小麦基因型根尖酶活性无显著差异;铝处理6h后,扬麦5号根尖SOD活性显著高于鉴-864,而鉴-864根尖CAT和APX活性显著高于扬麦5号.2个小麦基因型根尖MDA含量随着铝处理时间的增加而升高,在铝处理3h时,2个小麦基因型无显著差异;铝处理6h后,扬麦5号显著高于鉴-864.H2O2含量随着铝处理时间的延长而上升,以敏感基因型积累较多.可见,与小麦耐性基因型相比,在铝胁迫下小麦敏感基因型根尖SOD活性较高而CAT、APX活性较低,从而引起H2O2过量积累而导致氧化胁迫,使细胞的脂质过氧化程度加剧,最终严重抑制根系伸长.

The time-dependent effects of aluminum （Al） stress on root elongation, aluminum content, superoxide dismutase （SOD）, catalase （CAT）, ascorbate peroxidase （APX）, malondialdehyde （MDA） and H2O2 in the root tips of Al-resistant （Jian-864） and Al-sensitive （Yangmai-5） genotypes of wheat （ Triticum aestivum L. ） were investigated by using hydroponics. Root elongation of both genotypes was greatly inhibited with the increasing exposure time to 30μmol·L^-1 AlCl3, but more inhibition of root elongation was observed in Yangmai-5. Total Al content in root tips increased as time passed by, with total Al content significantly higher in Yangmai-5 than that in Jian-864. The SOD, CAT and APX activities in root tips of both lines increased with increasing exposure time to Al. There was no significant difference in the 3 enzyme activities of both genotypes at 3 h exposure to Al. In contrast, SOD activity in Yanmgai-5 was distinctly higher than that in Jian-864, while CAT and APX activities in Jian- 864 were markedly higher than those in Yangmai-5 after 6 h exposure to Al. There was no remarkable difference in MDA content in both genotypes at 3 h exposure to Al, whereas MDA content in root tips of Yangmai-5 was significantly higher than that of Jian-864 after 6 h exposure to Al. Meanwhile, H2O2 content was also enhanced with the increasing exposure time to Al treatment, with more accumulation in Yangmai-5. In conclusion, compared with Al-tolerant genotype （Jian-864）, SOD activity in root tips of Al-sensitive genotype （Yangmai-5） was much higher and CAT and APX activities were relatively lower. As a result, H2O2 was excessively accumulated in Yangmai-5 and then leaded to oxidative stress and severe lipid peroxidation, thereby significantly inhibiting root elongation.