High variability in the tissue culture response of root-tips of Allium ascalonicum individuals and optimization of the regeneration procedure

This study assessed the shoot regeneration capacity of root-tips isolated from single seed-derived individual plants, obtained from a wild, open-pollinated micropopulation of shallot (Allium ascalonicum). Considerable variation was observed in the regeneration capacities of individual lines, ranging from 0.93 to 100 %, and a mean bud number per root explant between 0.09 and 20.67. One line was found to be superior, and was chosen for protocol optimization, focusing on the 2,4-D/BA ratio, duration of the CI phase and light conditions. The application of the optimized protocol to other lines, selected for their variable regeneration capacities, enhanced the process of regeneration and shortened the time required to obtain healthy plantlets, even in inferior lines. However, highly responsive lines remained superior, indicating that differences at the individual level must not be overlooked. The conditions employed in this study may serve as a base to facilitate the application of molecular breeding methods in shallot.