Water stress-regulated gene expression in Cicer arietinum seedlings and plants

Abstract

Water stress induces biochemical and physiological responses in plants, such as growth inhibition. A number of genes that respond to drought stress in Cicer arietinum are described and their expression patterns are studied in order to give an approach of their function. Genes coding for lipid transfer proteins (LTP) and late embryogenesis abundant (LEA) proteins seem to be important in chickpea water stress response. The induction of these genes is not exclusive of osmotic stress caused by polyethylene glycol, since they also showed a significant up-regulation by high salinity. These genes are not responsive to exogenous abscisic acid (ABA) treatment. CapLTP was mainly expressed in young tissues: messengers are more abundant in seedlings than in adult plants, and the transcript level decreased gradually as the age of epicotyls increased. In this sense, LTPs would be involved in cuticle synthesis during early developmental stages. CapLEA-1 and CapLEA-2 are markedly up-regulated by NaCl treatment in every seedling sections. The response of these genes to high salinity suggests their implication in protection of cellular functions from high ion concentration damage. Present results agree with the postulated role for group 3 LEAs in sequestering ions, thus palliating toxic effects of NaCl. The presence of LEAs in vegetative well-watered tissues suggests a new function for these proteins. Other cDNAs encoding glyoxalases, proline-rich proteins and raffinose synthases have also been identified as induced by water stress.