CONTROL OF HYPERHYDRICITY OF MANGO SOMATIC EMBRYOS

Hyperhydricity of immature somatic embryos has been a limiting factor for the development of highly embryogenic suspension cultures of many important mango cultivars. Reversion of hyperhydricity was achieved in two ways: 1) heart-stage somatic embryos (2-3 mm length) were partial ly dehydrated under controlled conditions at high relative humidity (R H) for 24-48 h and 2) the gelling agent (Gel-Gro) concentration of the plant growth medium was increased from 2.0 to 6.0 g 1(-1). Partially dehydrated immature somatic embryos were normal in appearance. Somatic embryos that were partially dehydrated germinated precociously when c ultured on maturation medium. Although abscisic acid (ABA) did not rev erse hyperhydricity of primary somatic embryos, ABA did stimulate the reversal of this abnormal pattern of development among secondary embry os. ABA (500 mu M) inhibited precocious germination and permitted soma tic embryo maturation. Partially dehydrated, immature somatic embryos (4-7 mm long) remained viable for up to 32 days in the absence of matu ration medium under high RH.