Control of hyperhydricity of mango somatic embryos.
Monsalud M. J., Mathews H., Litz R. E., Gray D. J.
Author Affiliation: University of Florida, Tropical Research and Education Center, 18905 S.W. 280 St., Homestead, FL 33031, USA.
Plant Cell, Tissue and Organ Culture 42 : 195-206
Abstract : 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 studied in mango somatic embryos derived from cultured ovules, and was achieved in two ways: (1) heart-stage somatic embryos (2-3 mm length) were partially dehydrated under controlled conditions at high relative humidity (RH) for 24-48 h; and (2) the gelling agent (Gel-Gro) concentration of the growth medium was increased from 2 to 6 g/litre. Partially dehydrated immature somatic embryos were normal in appearance. Somatic embryos that were partially dehydrated germinated precociously when cultured on maturation medium. Although abscisic acid (ABA) did not reverse hyperhydricity of primary somatic embryos, ABA did stimulate the reversal of this abnormal pattern of development among secondary embryos. ABA (500 µM) inhibited precocious germination and permitted somatic embryo maturation. Partially dehydrated, immature somatic embryos (4-7 mm long) remained viable for up to 32 days in the absence of maturation under high RH.