Rejuvenation of Adult Specimens of Castanea Sativa Mill: Through In Vitro Micropropagation

Abstract

Castanea sativa is a woody plant difficult to propagate by conventional methods. Cuttings are difficult to root, and, due to the almost complete autoincompatibility, the levels of heterozygoty are very high, thus compromising programs of propagation by seeds. Until recently some success was obtained on the micropropagation of adult plants of C.sativa × C.crenata hybrids (reviewed by Vieitez et al.,1986). However, as stressed by several authors trees and shrubs can only be selected for cloning when they are adult (cf. Bonga and Durzan,eds.,1982, and Pierik,1987). As a consequence, efficient methods of micropropagation of adult specimens are required if cloning of a specific tree is needed. In C.sativa different attempts of micropropagate adult material have failed systematically in the rooting step (Chevre, 1985; Mullins, 1987). The presence of rooting inhibitors in mature material may be one of the reasons of this failure, since this kind of compounds seems to be absent from juvenile and etiolated material (Gesto et al.,1977; Vieitez et al.,1987). Since C.sativa lacks other precise juvenility markers, the ability of rooting could therefore be considered as a rough rejuvenation marker. Recently a complete process of micropropagation of adult material of C.sativa has been described (Feijô and Pais,1988; Feijô and Pais,1989). This paper describes some results on this process related to a possible rejuvenation occurring in vitro.