SCREENING OF LARGE NUMBERS OF SEED FAMILIES OF PINUS-STROBUS L. FOR SOMATIC EMBRYOGENESIS FROM IMMATURE AND MATURE ZYGOTIC EMBRYOS

The somatic embryogenic process was investigated using immature and ma ture zygotic embryos originating from 13 open-pollinated seed families selected for their embryogenic capacity from over 128 seed families o f Pinus strobus. In a first step, intact megagametophytes with precoty ledonary embryos from these families were placed on modified Litvay me dium. Embryogenic tissues (ETs) were obtained for 12 of them, with ini tiation rates varying from 2.6% to 23%. On average, 14% of the ETs (36 /258) formed stable embryogenic cell lines (ECLs) after 4-6 months of subculture. Mature somatic embryos were produced for 30 out of 52 cell lines, and plants were regenerated. Later, initiation of ETs from mat ure zygotic embryos was also tested for the selected families. ECLs we re obtained for five of them, with a maximum initiation rate of 2.7%, and plants were produced for four ECLs.