Caracterização fisiológica e molecular de sementes de Poincianella pyramidalis (Tul.). L. P. Queiroz (Leguminosae-Caesalpinioideae) submetidas a estresses abióticos

Abstract

The formation of high quality seeds is a basic pre-requisite to generate vigorous seedlings, that tolerate the various types of biotic and abiotic stresses (as drought and heat) which limit agricultural yield and productivity. In this context, the use of techniques that increase seed vigour (as osmopriming) might have a positive effect on plant production. This approach aimed to establish the germinative behavior of Poincianella pyramidalis (catingueira) seeds in different conditions of temperature and osmotic potentials, as well as to determine the molecular and physiological base involved in the response of the seeds to osmopriming. The assays involving incubation of catingueira seeds in different temperatures (20, 25, 30, 35, 37 e 40ºC) and osmotic potentials (0,0; -0,2; -0,4; -0,6; -0,8; -1,0; -1,2 MPa) showed that the species has a wide ecology plasticity (once it is able to germinate in all studied temperatures) and moderate tolerance to osmotic stress (germination was kept until -1.0 MPa potential and formation of normal seedlings until -0.6 MPa potential). Osmopriming increases catingueira seed vigour (rate and uniformity of germination are maximized), reverts the negative effects of accelerated ageing at 40 ºC (but not at 45 ºC), does not compromise longevity of seeds stored for two years in the fridge, does not revert the effects of extremely stressful conditions (as overly negative osmotic potentials and higher temperatures) and does not influence in emergence and development of catingueira seedlings. Many genes are involved in the improvement of catingueira seed vigour after osmopriming application. These genes are related to metabolic functions that are reactivated in the osmopriming condition. The information generated from this proposal serves as a base to study others species from the Brazilian Northeastern Semi-arid.