Culture of very young Phaseolus vulgaris L. pods and plantlet regeneration

In order to rescue early aborting hybrids between Phaseolus polyanthus Greenm. (female) x Phaseolus vulgaris L., a pod culture technique was developed on 2-day old P. vulgaris pods. Seven different culture techniques are described using a modified Phillips et al. (1982) medium for maturation. The application of high and variable osmolality conditions similar to what is observed in vivo during pod culture (1 wk) and before extracting the embryos, gave the best results in terms of pod, ovule and embryo development. Our pod culture technique is a valuable way to rescue very immature embryos. High germination rates can be obtained, plantlet survival is higher than in any other technique used before and, for the first time, plantlet regeneration has been obtained from 2 days old P. vulgaris embryos. This technique could provide an alternative solution for crossing Phaseolus species when embryos abort at very early stages.