Khanna Palak, Kaur Kamaljit, Gupta Anil K
Indian J Exp Biol. 2016 Jun;54(6):386-93.
High temperature is one of the important stress factors that affect crops in tropical countries. Plants do evolve or adopt different mechanisms to overcome such stress for survival. It is an interesting subject and has attracted many researchers to work upon. Here, we studied the effect of salicylic acid (SA) on seedling growth and antioxidative defense system in two spring maize (Zea mays L.) genotypes viz., CML-32 (relatively heat tolerant) and LM-11 (relatively heat susceptible), under high temperature stress. High temperature induced greater reduction in dry biomass of LM-1 1 seedlings as compared to those of CML-32. There was a parallel increase in ascorbate peroxidase and glutathione reductase activities in the roots of CML-32 seedlings. However, the activities of catalase and superoxide dismutase decreased and the contents of H202, proline and malonaldialdehyde (MDA) increased in seedlings of both the genotypes. Application of SA (400 µM) led to increased dry biomass in heat stressed CML-32 seedlings. It improved the efficiency of Halliwell-Asada pathway in roots of CML-32 seedlings as was evidenced by the enhanced ascorbate peroxidase and glutathione reductase activities. The activities of catalase and superoxide dismutase increased in both the tissues of LM-11 seedlings, whereas in CML-32, it was only in shoots, after SA application. Peroxidase activity increased in SA treated seedlings of both the genotypes, though the increase was comparatively higher in CML-32. The contents of H₂O₂ and MDA decreased and that of proline increased in SA treated seedlings of both the genotypes, under stress conditions. It may be concluded that SA induced differential antioxidant response by upregulating Halliwell-Asada pathway in roots and attaining high POX activity in both the tissues of CML-32 seedlings, under high temperature stress.
高温是影响热带国家农作物的重要胁迫因素之一。植物确实会进化或采用不同机制来克服这种胁迫以求得生存。这是一个有趣的课题，吸引了许多研究人员开展相关工作。在此，我们研究了水杨酸（SA）对两种春玉米（Zea mays L.）基因型，即CML - 32（相对耐热）和LM - 11（相对热敏感）在高温胁迫下幼苗生长和抗氧化防御系统的影响。与CML - 32相比，高温导致LM - 11幼苗的干生物量下降幅度更大。CML - 32幼苗根系中的抗坏血酸过氧化物酶和谷胱甘肽还原酶活性呈平行增加。然而，两种基因型幼苗中的过氧化氢酶和超氧化物歧化酶活性下降，H2O2、脯氨酸和丙二醛（MDA）含量增加。施用SA（400 µM）使热胁迫下的CML - 32幼苗干生物量增加。抗坏血酸过氧化物酶和谷胱甘肽还原酶活性增强，证明其提高了CML - 32幼苗根系中哈氏 - 阿萨达途径的效率。施用SA后，LM - 11幼苗的两个组织中过氧化氢酶和超氧化物歧化酶活性均增加，而在CML - 32中，仅地上部分增加。两种基因型经SA处理的幼苗中过氧化物酶活性均增加，不过CML - 32中的增加幅度相对更高。在胁迫条件下，两种基因型经SA处理的幼苗中H₂O₂和MDA含量下降，脯氨酸含量增加。可以得出结论，在高温胁迫下，SA通过上调CML - 32幼苗根系中的哈氏 - 阿萨达途径并使其两个组织中获得高POX活性来诱导不同的抗氧化反应。
