In vitro plant regeneration via indirect organogenesis from different explants of Lathyrus sativus L. and Lathyrus cicera L.

The grass pea (Lathyrus sativus L.) and flatpod peavine (Lathyrus cicera L.) are the most economically important and widely cultivated Lathyrus species. However, their utilization is limited due to the presence of their endogenous toxin beta-N-oxalyl-L-alpha, beta-diaminopropionic acid (beta-ODAP). Thus, a beta-ODAP free variety should be developed through some plant breeding technique like either mutational breeding or genetic-manipulation. In this circumstance, the plant regeneration of Lathyrus species becomes a bottleneck. In the present study, an efficient system for in vitro regeneration of L. sativus with high beta-ODAP levels, and L. cicera with low beta-ODAP levels, was developed from different explants (axillary buds, leaves and stems). At first, the green nodular calli were induced from sterile seedlings. It was found that the pre-culture of sterile seedlings with 15 mg/L 6-benzyladenine (BA) was necessary for L. cicera, but not for L. sativus. All of these calli were able to differentiate into adventitious shoot formation when cultured further. Among those explants, leaf segments were the optimum because of their easy obtainment and high regeneration efficiency (i.e., 66.48% in L. sativus and 62.13% in L. cicera). Furthermore, it was found that the pre-treatment would significantly improve the efficiency for nodular calli induction in both varieties, although it was easier on explants of L. sativus than on those of L. cicera. When these in vitro-derived plantlets of the two Lathyrus species were planted on half-strength Murashige and Skoog medium (MS) medium with alpha-naphthalene acetic acid (NAA) supplemented, 60% of them developed several roots. After being transplanted into soil, above 85% of each Lathyrus species grew well. The protocol would be useful for further expanding the propagation and Agrobacterium-mediated genetic transformation to obtain low beta-ODAP varieties.