两个不同耐铝玉米自交系根系对铝毒胁迫的响应

Responses of two maize inbred lines of different aluminium tolerance to Alinduced oxidative stress

通过铝(Al)毒胁迫处理,检测两个不同耐Al玉米自交系(耐Al自交系178和Al敏感自交系Mo17)根系氧化胁迫相关指标如Al含量、H2O2含量、丙二醛(MDA)含量,抵御氧化胁迫的过氧化物酶(POD)活性及细胞壁木质素含量,以期为揭示Al毒抑制玉米根系发育的机制提供佐证.结果表明,Al毒处理后,两个玉米自交系根系的Al含量、H2O2含量、MDA含量、木质素含量和POD活性均有所增加.当Al处理24 h时,这些生理指标变化最大.其中,178中木质素含量和POD活性增加幅度大于Mo17,分别为0.126 OD和2.04 U;而Mo17中Al含量、H2O2含量和MDA含量增加幅度更大,分别为1.835μg g-1、16.71μmol g-1和40.2 nmol g-1.综上,玉米根系的生长抑制与Al诱导的膜脂过氧化有关,而根系细胞抗氧化酶POD的活性及木质素含量的变化是玉米对Al毒胁迫的一种诱发性防御反应.

Aluminium（Al） toxicity seriously inhibits root growth and development of plants in acid soils. Root growth inhibition is the most obvious phenotype observable shortly after Al exposure. Previous reports believed Al triggered oxidative stress and further activated defense responses of plant. In China maize is seriously stressed by Al due to the rapid spread of acid soil, but the reason of root growth inhibition is still unknown. This study aimed to understand the mechanism of root growth inhibition under Al stress. We investigated the parameters relative to oxidative stress, including content of aluminium, hydrogen peroxide（H2O2）, malondialdehyde（MDA）, and those involved in defense responses such as oxidative stress activity of peroxidase and content of lignin. The result showed that all values, including content of Al, H2O2, MDA, content of lignin, activity of peroxidase, increased in both maize lines after Al treatment. Notably, after Al exposure for 24 h, the changes of the physiological parameters were in maximum. Meanwhile, lignin content and the activity of peroxidase were increased, up to the peak value of 0.126 OD and 2.04 U, respectively, in the Al tolerant 178, much higher than that of the Al sensitive Mo17. On the contrary, the maximum content of Al, H2O2 and MDA in Mo17 was 1.835 μg g-1, 16.71 μmol g-1, 40.2 nmol g-1, respectively, after Al treatment, much higher than that in 178. These results suggested that the inhibition of maize root growth is correlated with the Al-induced lipid peroxidation, and that the changes of lignin content and activity of peroxidase may be a defense response caused by Al toxicity in maize.