engleski

Efficient plant regeneration of Begonia semperflorens and Begonia spp. from petiole and leaf explants

Efficient plant regeneration of intended genotypes is a prerequisite for the genetic modifications, mutation breeding and in vitro somaclones production. Petiole and leaf segments of two begonia genotypes, Begonia semperflorens cv. “Eureka” and Begonia spp. were used for in vitro adventitious bud induction and plant regeneration. Begonia spp. is 6th selfing generation after crossing B. semperflorens and Begonia x hybrida cv. “Dragon Wings”. Excised explants were placed on agar-solidified Murashige and Skoog (MS) media supplemented with 0.2 mg l-1 naphthalene-acetic acid (NAA) + 0.5 mg l-1 6-benzylaminopurine (BA) (MS1-treatment 1) or thidiazuron (TDZ) (MS2-treatment 2), or were soaked in liquid ½ MS medium supplemented with 9.0 mg l-1 BA (MSBA) or TDZ (MSTDZ) and then transferred to hormone-free MS medium (MSHF) (treatment 3 and 4, respectively). Initial necrosis of explants was a considerable problem in this study. The highest percentage of necrosis occurred when explants, especially leaf explants, were exposed to a high concentration of BA or TDZ (treatments 3 and 4) and then transferred to MSHF medium. Explants that survived formed adventitious buds with different rates of efficiency depending on genotype and treatment. B. semperflorens cv. Eureka formed, in average, adventitious buds on 47.3% and Begonia spp. on 13% of explants. The mean percentages of adventitious bud formation recorded in treatment 3 (55.0%) and 4 (53.7%) were significantly higher than in treatments 1 (32.1%) and 2 (16.8%). Petiole and leaf explants responded to bud induction with similar efficiency (31% and 29.3%, respectively). The final regeneration efficiency expressed as a number of shoots per responding explant significantly differed only according to explant type. Petiole explants produced in average 5.3 and leaf explants only 1.7 shoots per responding explant. Efficient plant regeneration of Begonia spp. genotype indicates that homozygous parental lines of wax begonias could be amenable to efficient in vitro regeneration. Different treatments resulted with similar mean number of shoots per responding explant (2.9 - 4.1), but the treatments with BA could be recommended for plant regeneration as it induced normal shoots, while TDZ caused stunted growth.

Begonia semperflorens; Begonia spp.; plant regeneration; adventitious buds; direct organogenesis; explant type; medium

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