Regeneration in Tetrapleura tetraptera via Indirect Somatic Embryogenesis from Isolated Axillary Meristems

Abstract

To facilitate the use of biotechnological techniques for conservation, germplasm exchange and improvement of Tetrapleura tetraptera, the study investigated in vitro plant regeneration via somatic embryogenesis from isolated axillary meristem of the plant. Indirect primary somatic embryos were induced on MS basal medium supplemented with nine different concentrations of 2,4-D. Pre-embryogenic calli were made to mature on MS basal medium containing BAP alone or with four concentrations of NAA. Secondary somatic embryos were induced on MS basal medium supplemented with nine different concentrations of 2,4-D. Maturation of the secondary pre-embryogenic calli took place on MS medium fortified with eight concentrations of BAP. Medium fortified with 6.0 mg/l 2, 4-D had the highest frequency of primary embryogenic callus (16.4%) and average number of primary immature embryo per callus (2.3). Culture media supplemented with 0.6 mg/l BAP and 0.1 mg/l NAA recorded the highest primary embryogenesis (24.5%) and average number of matured primary embryo per explant (2.8 embryos/explants). Medium fortified with 1.2 mg/l BAP gave the highest secondary embryogenesis (72.4%) and average number of matured embryo per callus (3.1 embryos per callus). Explants in medium receiving 1.0 mg/l BAP and 0.7 mg/l IBA recorded largest number of shoot-bud (27.6%) and average number of shoot-bud per explant (2.4/explant) with vigorous and green appearance. Shoot elongation was greatest in medium fortified with 1.0 mg/l BAP and 15.0 mg/l IBA with vigorous appearance. The largest number of roots (4.3/plantlet) were formed by plantlets grown in medium supplemented with 1.0 mg/l BAP and 15.0 mg/l IBA with normal appearance. The study concluded that indirect somatic embryos obtained from isolated axillary meristem with 2,4- D, BAP, NAA were capable of regeneration into normal vigorous plants.