Unique anatomic adaptations in recalcitrant fruits of the genus Ouercus both delay desiccation stress and promote water uptake

摘要

Desiccation-sensitive recalcitrant seeds and fruits are killed by the loss of even moderate quantities of water. Consequently, minimizing the rate of water loss may be an important ecological factor and evolutionary driver by reducing the risk of mortality during post-dispersal dry-spells. Thus, desiccation sensitivity has obvious disadvantages in the event of dry spells after dispersal. However, for recalcitrant fruits of a range of Quercus species, prolonged drying times have been observed previously (Xia era/ 2012a). With ca. 450 species, Quercus is the largest and most widely distributed genus in the Fagaceae. Species from the genus are widespread in habitats ranging from temperate and tropical forests to dry thorn scrub and semi-desert. The lack of a relationship between fruit oil content / fruit size and drying rates was reported (Xia et al 2010, 2012a) suggesting that instead, pericarp anatomical characteristics may be important for regulating the rate of water loss / uptake. However, the underlying mechanism(s) regulating water loss and subsequent water uptake (imbibition) in fruits of Quercus species are still poorly known.