<i>In vitro</i> regeneration of ‘Feizixiao’ litchi (<i>Litchi chinensis</i> Sonn.)

Abstract

A simple efficient in vitro plant regeneration system was developed by indirect somatic embryogenesis of ‘Feizixiao’ litchi (Litchi chinensis Sonn.). Pollen in the anther of monocytes was used to induce callus. Two auxins (naphthalene acetic acid [NAA] and 2,4-dichloriphenoxyacetic acid [2,4-D]), and two cytokines (kinetin [KT] and 6-benzyladenine [BA]) were tested to explore their influence on callus induction. MS medium supplemented with 2.22 μM BA, 2.69 μM NAA, 13.57 μM 2,4-D, and 0.4 g/L LH (lactalbumin hydrolysate) showed the highest callus induction frequency. The callus obtained from anther was subcultured in MS medium containing 4.52 μM 2,4-D to obtain synchronized friable embryogenic callus. Different developmental stages of SEs were obtained from the callus on MS medium containing 6% (w/v) sucrose and different PGRs (plant growth regulators). On MS medium containing 6% (w/v) sucrose and supplemented with 0.54 μM NAA, 23.23 μM KT, 0.4 g/L LH, 0.56 μM inositol, and 10% (w/v) CW (coconut water), a higher number of SEs (globular, heart, torpedo and cotyledonary embryos) was achieved than on other media. Plantlets were established onto half-strength MS medium containing 1.44 μM GA₃ (gibberellic acid) followed by successful acclimatization in the greenhouse. With flow cytometry and chromosome counting, ploidy analysis of regenerated plants revealed that the regenerated plantlets were all diploid. This study is the first report on somatic embryogenesis of ‘Feizixiao litchi’, providing an opportunity to improve the cultivar by biotechnology methods.

Keywords: litchi (Litchi chinensis Sonn.), anther culture, callus, regeneration, somatic embryogenesis