Phenotypic variation during micropropagation of the chimeralRhododendron ?President Roosevelt?

Abstract

The putative periclinal chimera Rhododendron × limbatum 'President Roosevelt' was used to study the origin of shoots in vitro. Genotypic segregation readily occurred in vitro. Numerous phenotypes were observed, although most shoots were either entirely green or maintained the original variegation pattern. Derivatives of the third apical layer were rarely involved in shoot formation. A reversed chimeral form was isolated. Adventitious shoots were usually miniaturized and rapidly proliferating, but axillary shoots had thicker stems, larger leaves and proliferated more slowly. Corolla tissue produced stunted, leafy shoots; no variegated shoots were produced from floret explants. In shoot tip cultures the addition of 40/~M 2iP without IBA resulted in the greatest number of shoots. Explant choice was the most critical factor for maintenance of foliar variegation.

Effects of the in vitro behavior of micropropagated plants on the stability of variegation in Yucca gloriosa, Phormium tenax, and Cordyline australis cultivars

“…Nevertheless, histological analyses revealed that all of the cell layers can be at the origin of an adventitious meristem, with the possibility of a multicellular origin, sometimes leading, even in small proportions, to variegated plants arising from adventitious regeneration (Marcotrigiano, 1986;Nabeshima et al, 2017). The consequence is that numerous studies have shown that propagation of periclinal chimeras by axillary bud meristems maintained a chimeric structure, whereas adventitious meristems led to the reorganization of cell layers and to very low rates of true-to-type plants (Papachatzi et al, 1981;Pierik et al, 1983;Lineberger and Wanstreet, 1983;McPheeters and Skirvin, 1983;Lineberger and Druckenbrod, 1985;Marcotrigiano, 1986;Pogany and Lineberger, 1990;Marcotrigiano et al, 1997;Amory and Gill, 1999).…”

“…For the specific case of periclinal chimeras, the mode of multiplication has a very pronounced effect on the maintenance of the variegated character. A high proportion of true-to-type plants are obtained by axillary branching (preformed meristems), while the adventitious meristems from organogenesis modes reveal very high frequencies of off-type plants in many genera like Yucca (Pierik and Steegmans, 1983), Ajuga reptans (Lineberger and Wanstreet, 1983), Rubus (McPheeters and Skirvin, 1983), Saintpaulia (Lineberger and Druckenbrod, 1985), Nicotiana (Marcotrigiano, 1986), Rhododendron (Pogany and Lineberger, 1990), Fragaria (Marcotrigiano et al, 1997) and Liriope (Amory and Gill, 1999).…”

Somaclonal Variation and Induced Mutations in Crop Improvement

“…The control of the extent of obtained varia- Mitteau, 1986 Dommergues andGillot, 1983 Pogany and Lineberger, 1990Lineberger et al, 1993 o Improving ornamental plants 91 tion may have relevance for ornamental plant breeders wanting to reach an equilibrium between the negative effects of random variation in propagation and the positive induction of useful mutants. The control of the extent of obtained varia- Mitteau, 1986 Dommergues andGillot, 1983 Pogany and Lineberger, 1990Lineberger et al, 1993 o Improving ornamental plants 91 tion may have relevance for ornamental plant breeders wanting to reach an equilibrium between the negative effects of random variation in propagation and the positive induction of useful mutants.…”