Accumulation of proline in leaves of sorghum genotypes (Sorghum bicolor L. Moench) which differ in their response to drought

Abstract

The accumulation of proline in the leaves of three sorghum genotypes, which differ in their response to drought was determined by measuring the water potential, their components and the proline content at the end of a water stress applied at three phenological stages. Results indicate that water stress induces increments in the proline content, depending on the phenological stage in which the stress happens and on the genotype, since the differences between genotypes were significant only when drought was applied at flag leaf stage. The resistant genotype UAT 152 accumulated the most proline when water stress was applied at flag leaf stage and at panicle initiation. It was concluded that higher proline accumulation under water stress could be a physiological mechanism of sorghum genotypes that confering resistance to this factor due to its relationship with the turgor maintenance, explained by a reduction in the osmotic potential and its possible contribution to osmotic adjustment, mainly in the drought resistant genotypes. In this study, accumulation in leaves, suggests that the differences between resistant genotypes and the susceptible one, may involve not only this mechanism, but also the capacity of proline translocation to the root, like in the case of the resistant genotype UAT 124; or other osmolytes like ABA, that can explain the behavior in the osmotic potential and, consequently, in the water potential.