Effect of Culture Conditions on in vitro lnduction of Adventitious Buds from Leaf Explant in Pepper (Capsicum annuum L.)

Effect of culture conditions on in vitro induction of adventitious buds from leaf explant was studied in pepper cv. 'Shosuke' (Capsicum annuum L.), to establish mass propagation method of genic male sterile line, 'ms-Shosuke', which is in practice used for hybrid seed production. Left explant was trimmed from aseptically grown seedling, and a proximal quarter part of the leaf along with a small portion of petiole was placed on MS agar medium with the proximal cut end embedded in the medium. The cultures were kept at 27℃, and illuminated for 16 hours per day (3000 lux). Leaf explants trimmed from 30 days old seedlings were inoculated on MS media supplemented with different concentrations of zeatin and casein hydrolysate (Table 1), and of BAP and IBA (Table 2). Adventitious buds were induced at high frequency on all of the culture media. Among them the following media were recommended: one to be supplemented with 3mg/I zeatin and 100mg/I casein hydrolysate, and the other with 3~5mg/I BAP and 0.2mg/I IBA. Physiological age of leaf explant, which was expressed as seedling age, proved to be a crucial factor to determine differentiation ability. Average number of adventitious buds induced from an explant was more than 12, when the explant was trimmed from 25 days old seedling (Table 3). IT was therefore concluded that just unfolded young leaf should be used as explant. To promote the development of shoots from adventitious buds, the cultures were transferred to MS medium supplemented with 1mg/I zeatin. Then well developed shoots were dipped in 1mg/I IAA solution for three days and aseptically grown on vermiculite, resulting in the establishment of plantlets with roots. Although rooting occurred in all shoots, the efficiency of shoot development from adventitious buds was only 21% in the best case (Table 4). Therefore the culture method must be further improved to increase efficiency.