Studies of androgenic processes in diploid potato

Abstract

Androgenic processes in diploid potato (2n=2x=24) were studied in three interspecific hybrids. Five incubation temperature treatments were examined. Temperature shock (35°C) during the first 12 h of anther culture and elevated incubation temperature (30°C 16h/20°C 8h) (hereafter 35°C-30°C/20°C) enhanced androgenic embryo production. Variation among experiment dates was highly significant. Temperature treatment (35°C-30°C/20°C) during anther culture did not influence the subsequent conversion rate of androgenic embryos, thus providing a simple and effective way to enhance androgenic embryo yield.

Repeated experiments were conducted to study extended anther culture by replacing anthers into medium following the usual harvest 6 weeks after culture initiation. Embryos continued to be produced after the first harvest. Embryo yield at the first harvest was significantly correlated with that at the second harvest (P <0.01). Significantly more embryos were produced when anthers were put back into the same medium compared to fresh medium in extended anther culture. Although relatively high embryo yield was produced in extended anther culture, high contamination and low regeneration rate eliminate any practical use unless a better regeneration protocol is developed.

Randomly amplified polymorphic DNA (RAPD) techniques were applied to analyze the genetic composition of anther-derived plants, whose ploidy level was predetermined by flow cytometry. The RAPD fragments amplified from various anther derived diploid plants (2n=2x=24) were compared with those from anther donor (2n=2x=24) and anther-derived monoploids (2n=1x=12). Anther donor and anther-derived monoploids were distinguished by scoring segregating bands as well as total number of scorable bands that exhibited polymorphism. Thus RAPD has the potential to separate homozygous from heterozygous diploids, since the frequency of RAPDs present in homozygous diploids is expected to be the same as in a group of known monoploids, whereas heterozygous ones will be similar to the anther donor.