Physiological Basis of Excessive Soil Moisture Tolerance in Tropical Maize
Response of maize plants to excessive moisture (EM) stress has been studied extensively, however, systematic information on the cascade of events conferring the EM-tolerance is yet to be established. This study was undertaken to assess the stress- adaptive physiological changes associated with EM- induced anoxic conditions, and to establish mechanism of EM-tolerance in tropical maize. Tropical/sub- tropical elite maize in bred lines, having different genetic background, were used in this study. Germplasm were exposed to EM-stress at knee-high stage (V7) by flooding the plots continuously for seven days. EM-induced changes in root geotropism (surface rooting) and increased brace roots development were identified as stress-responsive traits, however, the later one was found to be an stress-adaptive trait resulting in improved tolerance to the stress. Anatomical studies showed drastic changes in cortical region of root tissues in tolerant genotypes in terms formation of large aerenchymatous spaces. With regards to stress-induced metabolic changes increased NAD--alcohol dehydrogenase (ADH) activity was prevalent in all the genotypes under EM-conditions. Though the enzyme activity was slightly higher in tolerant entries but not high enough to justify the significant genotypic variability. However, the product of ADH-activity (ethanol) was relatively much higher in root and leaf tissues of susceptible genotypes. Analysis of ethanol concentration in shoot, root and inundated water showed that the level of ethanol was relatively much higher in the water present in rhizosphere of relatively tolerant genotypes. This finding suggests that EM-tolerant maize genotypes were able to extrude the toxic level of ethanol from root tissues to rhizosphere. Our findings suggest that mechanism of EM-tolerance in maize germplasm involves morphological and anatomical adaptation through development of brace roots and aerenchyma formation, and metabolic adjustment through regulatory induction of alcohol dehydrogenase (ADH) and extrusion of ethanol out of root tissues.
Maize Zea mays Excessive moisture Water-logging Tolerance mechanism
Pervez H. Zaidi P. Maniselvan Poonam Yadav P. Dureja N.N. Singh G. Srinivasan
Directorate of Maize Research, Pusa Campus, New Oelhi-110012, India Division of Agro-chemical, Indian Agricultural Research Institute, New Delhi-12, India Intensive Agro-ecosystem Program (IAP), CIMMYT, Mexico
国际会议
第九届亚洲玉米大会(the Ninth Asian Regional Maize Workshop)
北京
英文
224-227
2005-09-05（万方平台首次上网日期，不代表论文的发表时间）