Open the Windows toward Somatic Embryogenesis of Leaf Explants of Persian Walnut (Juglans regia L.)

Leaves from in vitro proliferating shoots of cvs. Chandler and Hartley of Persian walnut were cultured on MS and NN media supplemented with BA and NAA. Three light conditions including darkness, low light intensity and modified light intensity were used. Most of the calli were friable and non-embryonic in all three conditions. Rate of callogenesis depended on cultivar, culture medium, light conditions, and interaction between them. In the sixth week, all individual effects and interaction effects were significant and the highest rate of callogenesis were achieved from cv. Hartley on NN medium in the darkness and low light intensity conditions and the lowest one was in cv. Chandler on MS medium in the low light intensity and on NN medium in the modified light intensity conditions. However, in the tenth week, just individual effects of cultivars, light conditions, and media were significant and rate of callogenesis in Hartley, NN medium and dark conditions were more than Chandler, MS medium and other light conditions. Three months after culturing of leaf explant on plant-growth-regulator-free media, gradually, frequency of callogenesis decreased. Browning of explants and calli was more in the MS media, cv. Chandler and darkness or low light intensity conditions. At the end of five months after initial culture, no embryo was formed from these calli