Department of Plant Sciences

Common bean is the most important food legume in the world particularly for developing countries in the tropics, where it is produced on acid and Al-toxic soils. Al resistance in bean is known to be achieved through exudation of citrate from the root tip which chelates Al to a nontoxic form after a lag phase. Here we report on Al-induced transcriptional changes in the root tips of an Al-resistant bean cultivar using suppression subtractive hybridization. Four hours of Al treatment resulted in differential expression of a rage of genes. Genes involved in stress response, plant defense, signal transduction and translation were up-regulated while genes involved in metabolism were largely down-regulated. In addition, we also identified key genes involved in Al resistance. These include: voltage-dependent anion-selective channel, NADP-specific isocitrate dehydrogenase, Cytochrome P450 monooxygenase and F1-ATPase. The role of these genes in Al resistance is discussed.