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 mechanisms of EM tolerance in tropical maize. Tropical/sub-tropical elite maize inbred lines with different genetic backgrounds were used in this study. Germplasm were exposed to EM stress at knee- high stage (V7) by flooding field plots continuously for seven days. EM-induced changes in root geotro pism (surface rooting) and increased brace root development were identified as stress-responsive traits, however, only the latter was found to be a stress-adaptive trait resulting in improved tolerance to the stress. Anatomical studies showed drastic changes in the cortical region of root tissues in tolerant genotypes involving the formation of large aerenchymatous spaces. With regard to stress-induced metabolic changes, increased NAD+ -alcohol dehydrogenase (ADH) activity was prevalent in all the genotypes under EM conditions. Although the ADH activity was slightly higher (not statistically significant) in tolerant entries, 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 the rhizosphere. Our findings suggest that mechanisms of EM-tolerance in maize involve 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 Delhi-110012, India Division of Agro-chemical, India 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
112-115
2005-09-05（万方平台首次上网日期，不代表论文的发表时间）