Effect of activated charcoal, abscisic acid and polyethylene glycol on maturation, germination and conversion of Aesculus hippocastanum androgenic embryos

The influence of activated charcoal (AC), abscisic acid (ABA) and polyethylene glycol (PEG) on the maturation and conversion of horse chestnut (Aesculus hippocastanum L.) androgenic embryos weretested. Androgenic embryos originating from microspores and anther culture were maturated over 90 days. Androgenic embryos on media containing PEG (50 g l-1), in combination with AC (1 g l-1) showed arapid development of embryos in the cotyledonary stage and lowered percentage of abnormal structures. The best results of androgenic microspore embryo germination were observed on media supplemented with AC alone (99%) and in combination with PEG (100%). Also, the greatest number of androgenic microspore plants (18%) and androgenic anther plants (12%) were formed on media enriched with 1 % AC. Lowest germination percentages of 37 and 39% in microspore culture and 33 and38% in anther culture were obtained on maturation media with ABA 20 mg l-1 alone and in combination with AC 1g l-1. Flow cytometric analysis showed that most of the androgenic embryos were haploid, corresponding to their microspore origin, while half of these became diploid after maturation for 90 days. All regenerants originating from microspore culture were haploid immediately after germination, but only 10% embryos re ained haploidity after 3 years subculturing, while 10.5% were diploid, 73.5% tetraploid and 6% octaploid on hormone-free medium. Unlike those from anther culture, after 3 years of subculturing on hormone-free medium, there were no haploid regenerant from anther culture, while8.5% were diploid, 81% tetraploid and 10.5% octaploid