Morphogenesis in Sitka spruce (Picea sitchensis (Bong.) Carr.) bud cultures – tree maturation and explants from epicormic shoots

Abstract

The adventitious bud forming ability of Sitka spruce (Picea sitchensis (Bong.) Carr.) buds in vitro was found to be dependent upon the age of tree from which the explants were taken. Bud formation declined exponentially with increasing tree age when 1.0 and 10 lM 6-benzylaminopurine (BA) were used to induce adventitious buds. When less BA was used (0.1 lM) bud production was much lower with all ages of tree and no mathematical relationship between declining bud production and tree age was found. By a tree age of 6 years bud-forming ability had declined severely. Even the few buds that developed on older tree tissues failed to elongate into shoots, became necrotic and eventually died, indicating that adventitious bud induction in this species is not a rejuvenative process. Callusing of bud explants also declined with increasing tree age when 0.1 lM BA was used whilst very little callusing occurred at the higher cytokinin concentrations (1.0 and 10 lM BA). Tissue necrosis in vitro increased with tree age, whilst the ability of BA to retard necrosis declined with increasing tree age. Buds from epicormic shoots, formed on the lower trunks of 20-year-old trees when these were exposed to light, were not significantly better at forming adventitious buds in vitro than buds taken from the lower branches of the crown.

Coppicing Abilities of Decapitated Elite Tree Trunks of Selected Acacia Species Genotypes in Mixed-Species Plantation

“…This technique has also been used to rejuvenate matured species for the micropropagation of elite clones to reverse the influence of age effects on the rooting ability of shoots in in vitro cultures. Coppice shoots collected from 20-year-old Picea sitchensis were found to be excellent explants in culture, with improved rooting abilities [65]. Coppice materials from 5-year-old A. hybrid (A. auriculiformis × A. mangium) stumps were also reported to be the best in the induction and proliferation of explants in culture medium [66].…”

Micrografting of Pistacia vera L.: A review

“…The final success of micrografting largely relies on several different factors that make micrografting a quite complex procedure. The physiological state and the age of the donor plant of the explant from which the scion is multiplied are one of them (Selby et al, 2005). Generally, the explants are collected from aged plants not favorable in micropropagation because callus initiation is difficult from these explants, and exudation of toxic phenols in aged explants is more than those explants from plants at the juvenile stage (Ahmad et al, 2013).…”