Journal of Experimental Botany Effects of abscisic acid on somatic embryo maturation of hybrid larch

Somatic embryos of hybrid larch (Larix x lepto-europaea) which had been matured for 4 weeks on maturation medium, developed normally on medium supplemented with 60 //M ABA, but abnormally on medium with no ABA. A comparative structural and histochemical investigation was carried out on these two types of mature embryos. At the light microscope level, differences between both treatments were vis-ible only after 2-3 weeks of maturation. At around this time, abnormal development becomes evident macro-scopically: ABA-minus embryos remain rather stubby as opposed to the more cylindrically shaped ABA-plus embryos. Whereas somatic embryos matured with ABA consist of densely cytoplasmic cells showing a hig