Chugh Vishal, Kaur Narinder, Gupta Anil K
Department of Biochemistry, Punjab Agricultural University, Ludhiana 141004, India.
Indian J Biochem Biophys. 2011 Oct;48(5):346-52.
The present investigation was undertaken to identify the possible mode of mechanism that could provide tolerance to maize (Zea mays L.) seedlings under waterlogging. Using cup method, a number of maize genotypes were screened on the basis of survival of the seedlings kept under waterlogging. Two tolerant (LM5 and Parkash) and three susceptible (PMH2, JH3459 and LM14) genotypes were selected for the present study. Activities of antioxidant and ethanolic fermentation enzymes and content of hydrogen peroxide (H2O2), glutathione and ascorbic acid were determined in roots of these genotypes after 72 h of waterlogging. Waterlogging treatment caused decline in activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) in all the genotypes. However, only susceptible genotypes showed slight increase in glutathione reductase (GR) activity. Significant reduction in APX/GR ratio in susceptible genotypes might be the cause of their susceptibility to waterlogging. The tolerant seedlings had higher GR activity than susceptible genotypes under unstressed conditions. Stress led to decrease in H202 and increase in glutathione content of both tolerant and susceptible genotypes, but only tolerant genotypes exhibited increase in ascorbic acid under waterlogging conditions. In the tolerant genotypes, all the enzymes of anaerobic metabolism viz. alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH) and pyruvate decarboxylase (PDC) were upregulated under waterlogging, whereas in susceptible genotypes, only ADH was upregulated, suggesting that efficient upregulation of entire anaerobic metabolic machinery is essential for providing tolerance against waterlogging. The study provides a possible mechanism for waterlogging tolerance in maize.
本研究旨在确定在渍水条件下可能赋予玉米（Zea mays L.）幼苗耐受性的机制模式。采用杯栽法，根据渍水条件下幼苗的存活情况筛选了多个玉米基因型。本研究选择了两个耐渍基因型（LM5和Parkash）和三个敏感基因型（PMH2、JH3459和LM14）。在渍水72小时后，测定了这些基因型根系中抗氧化酶和乙醇发酵酶的活性以及过氧化氢（H2O2）、谷胱甘肽和抗坏血酸的含量。渍水处理导致所有基因型中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性下降。然而，只有敏感基因型的谷胱甘肽还原酶（GR）活性略有增加。敏感基因型中APX/GR比值的显著降低可能是其对渍水敏感的原因。在未受胁迫条件下，耐渍幼苗的GR活性高于敏感基因型。胁迫导致耐渍和敏感基因型的H2O2含量降低，谷胱甘肽含量增加，但只有耐渍基因型在渍水条件下抗坏血酸含量增加。在耐渍基因型中，厌氧代谢的所有酶，即乙醇脱氢酶（ADH）、醛脱氢酶（ALDH）和丙酮酸脱羧酶（PDC）在渍水条件下均上调，而在敏感基因型中，只有ADH上调，这表明整个厌氧代谢机制的有效上调对于提供耐渍性至关重要。该研究为玉米耐渍性提供了一种可能的机制。
