Biochemical and Morphological Changes during in vitro Rhizogenesis in Cuttings of Sequoia sempervirens (D. Don) Endl

Abstract

Summary Three-centimeter-long tip cuttings of Sequoia sempervirens (D. Don) Endl were cultivated in vitro continuously in the absence of auxin (basal medium), continuously in the presence of auxin (induction medium), and temporarily in induction medium, followed by transfer into basal medium (sequential medium). The majority of the cuttings grown in basal medium formed new shoots. Cuttings cultivated in induction medium grew poorly. Only cuttings grown in sequential medium rooted after callus formation in their basal parts. The soluble-protein content increased before root emergence. Peroxidase activity increased during the root induction phase. After the transfer into the basal medium and before the appearance of the first roots, there was a slight decrease or stabilization in peroxidase activity. Subsequently, peroxidase activity increased significantly, in parallel with increased rooting. Isoperoxidase patterns changed during rhizogenesis; some isozymes appeared only in the presence of exogenous auxin. The amount of phenolic compounds increased during the root-induction period and subsequently decreased to initial levels, following the transfer of the explants into the basal medium. Root primordia were detected approximately 14 d after the transfer into basal medium. The primordia differentiated from the calli formed at the basal portions of the cuttings.