Genotype-environment Interaction in the Desynapsis of a Hemerocallis 'Sleeping Beauty' Clone and its Progeny.

Abstract

Microsporogenesis was studied in the plants from a selfed clone of Hemerocallis ‘Sleeping Beauty’ showing regular meiosis under normal cultural conditions and desynapsis when subjected to stress of low water combined with high temperature. The progeny, grown under normal field conditions, had non-desynaptic and desynaptic plants in the ratio of 3:1 indicating that the parent clone was heterozygous and that the desynapsis was controlled by a single recessive gene. The studies revealed a gradation among different genotypes in their response to environmental conditions. The stress situation under which the heterozygote showed desynap-tic meiosis did not affect microsporogenesis in other cultivars. However, within the range of variation in environmental conditions during normal outdoor cultivation, the desynapsis heterozygote showed uniform bivalent pairing and non-significant differences in chiasma frequency. Desynapsis homozygotes, on the other hand, showed desynapsis even under normal field conditions and were affected by day to day fluctuations in ambient conditions showing prominent differences in bivalent and chiasma frequencies. The desynaptic plants, besides having low bivalent pairing, were characterized by delayed entry of MMCs into meiosis, high rate of suppression of meiosis, and blockage or highly irregular division following Al. Variation in the number of cells with different bivalents followed a binomial distribution in three desynaptic plants. In one it deviated significantly from the expected which was possibly due to intercellular differences.