Biochemical changes and development of leaf tracheary elements of a desert plant Fouquieria splendens ssp. breviflora exposed to water stress

Fouquieria splendens ssp. breviflora is a species of the family Fouquieriaceae, growing in arid zones of Mkico, between 700 and 2100 m above sea level (a.s.1). This species characteristically forms leaf buds under conditions of adequate water supply. The physiological response of this species was studied under varying conditions of irrigation in soil and water, using stems collected during two seasons: dry and rainy; evaluating the foliar material produced the quantity of free proline and total protein and anatomical foliar changes in the water conduction systems. This species displayed distinctive adaptive mechanisms involving the development of foliar fascicles differentiation of vessels with formation of tracheal elements, and, metabolically, a high proline and total protein content in the stems of the dry season, showing that the responses observed in F. splendens spp. breviflora are adaptive physiological responses that take place simultaneously, being evidence of the first mechanisms of response to water-stress conditions. Thus, this species is regarded as a poikilohydric plant, as it is capable of the regulation of its metabolism during bud development when flooding events occur in the species' habitat after a prolonged dry and desiccation period.