Abstract
Somatic embryos of borage (Borago officinalis L., Boraginaceae) were induced directly from immature zygotic embryos and indirectly from callus. Embryogenic callus maintained on liquid basal medium supplemented with 4.5 μm 2,4-D and 10% (v/v) coconut water (CW) produced globular structures that became rhizogenic upon transfer to 2,4-D-free basal medium. Embryogenic callus maintained on semisolid basal medium supplemented with 4.5 μm 2,4-D and 10% CW continued to produce somatic embryos, but development was abnormal. Globular structures often failed to develop cotyledons, and those that developed were small and fused; hypocotyls tended to be large and elongated. Root meristems appeared normal, but shoot meristems were not formed. Carbon source (sucrose, glucose, or maltose) and ABA did not normalize somatic embryogenesis. A highly embryogenic, non-browning clone produced various tissue types when 2,4-D was withdrawn that varied in total fatty acids: white nodular structures (12.6%), cotyledonary structures (22.5%), white callus (5.0%), green leafy growth (3.1%), and translucent globular growth (5.1%). γ-Linolenic acid, as a percentage of total fatty acids, was highest in cotyledonary structures (19.9%) and lowest in white callus (10.2%). Chemical names used: abscisic acid (ABA); 2,4-dichlorophenoxyacetic acid (2,4-D); coconut water (CW).