Somatic embryogenesis in Asparagus officinalis L. cv. Argenteuil: interactions between genotype, explant type and growth regulators on callus induction, growth and embryogenic differentiation

ABSTRACT

Callus induction, growth and embryogenic differentiation were studied in two selected genotypes of Asparagus officinalis L. cv. Argenteuil, to develop a protocol for somatic embryogenesis. Two experiments were carried out. In the first, four explant types (spear sections and lateral buds, both of in vivo and in vitro origin), and three levels of 2,4-D (1.5, 5 and 10 mg.l-1) and two of KIN (0 and 1 mg.l-1) added to MS basal medium, were tested during the three initial culture stages (90 d period). All factors were included in one factorial design to statistically analyze interaction effects. Interactions between genotype, explant type and time of culture initiation were significant for callus induction and growth during the two initial culture stages. The addition of kinetin enhanced callus induction and growth, and high levels of 2,4-D depressed callus growth. The average embryogenic differentiation was < 2 overall (11 with the best factor combination). In the second experiment, another explant type (bud clusters) was tested; the average embryogenic differentiation was 1.9 (best combination 5.6). For the two genotypes studied, the best factor combinations were the culture of in vivo lateral buds or bud clusters on MS basal medium with 1.5 mg.l-1 2,4-D and 1 mg.l-1 KIN.