Active metabolism during desiccation of the desiccation tolerant short-lived seeds of Poincianella pluviosa (DC.) L. P. Queiroz

Abstract

During embryogenesis and seed filling, developing seeds are metabolically highly active, while at the desiccation stage of tolerant seeds a decreased metabolism is expected. Seeds of Poincianella pluviosa present an extensive maturation cycle (11 months), longer than seed storability at room temperature (8 months). The metabolic profile of these seeds was characterized during maturation and drying, focusing in their role on seed behavior after shedding. Distinct responses of the embryonic axes and cotyledons to drying were observed depending on the developmental stage. Low proportions of tricarboxylic acids intermediaries until maturity indicated a low respiratory metabolism prior to the desiccation stage. Changes in shikimate, 4-coumarate, and quinate proportions suggest a metabolic shift towards the synthesis of chlorogenate isomers, found in high proportions in dispersed seeds. High proportions of lactate and glycerol were observed in immature seeds after artificial drying, but also in naturally dried axes of dispersed seeds. This suggests an active metabolism prior to drying and an osmotic stress under hypoxia, mechanisms that were never described before in desiccation-tolerant seeds. The results indicated that P. pluviosa seeds are dispersed with an incomplete metabolic switch-off, which can be related to their short lifespan.

Choosing the Right Path for the Successful Storage of Seeds

“…Mature orthodox seeds are developmentally arrested, metabolically quiescent, and dry. Thus, seeds shed or harvested at a MC of 20% or below are very likely to be orthodox [ 30 , 58 , 59 ]. In contrast, recalcitrant seeds are frequently shed from the mother plant at a MC of above 60% that may trigger germination [ 60 ].…”

“…Among the explanations of short-lived behavior is that seeds are dispersed without a complete metabolic shut-down, as in the case of desiccation tolerant Poincianella pluviosa (DC.) L. P. Queiroz [ 59 ]. Another reason may be related to a lack of endosperm and an energy reservoir, as in the case of Populus sp.…”