Transmissible reproductive changes following physiological adaptation to salinity in Sorghum bicolor

Abstract

A 3 wk exposure to 150mM NaCl induced adaptation to salinity in 8-d-old seedlings of Sorghum bicolor (L.) Moench. This treatment, defined as standard adaptation treatment, modified the expression of the reproductive traits, and the relationship between vegetative and reproductive organs. The adaptation response was accelerated When 8-d-old seedlings were sprayed daily with abscisic acid (ABA) for 10 d. Adaptation was also enhanced when seedlings were exposed to salinity on day 5, instead of day 8, after germination. These adaptation treatments, applied during the early vegetative development, influenced the expression of late reproductive characters. Thus besides the direct disturbing effect of NaCl, the adaptation process also has a specific influence on the expression of the sexual characters. Offspring of adapted plants were exposed to a standard adaptation treatment. The expression of the reproductive traits of the progeny was generally less perturbed than in their parents, where treatment influenced characters such as fertility, plant height and seed sue of the progeny. Therefore, the adaptation process induced stable and transmissible changes in the expression of the reproductive characters. An analogy between changes induced by salt adaptation in Sorghum plants and somaclonal variations is suggested. The evolutionary significance of the adaptation response is discussed.