Restoration of intact anthers in a thermosensitive, antherless, male-sterile cultivar of Asiatic hybrid lily in response to high temperature

Abstract

SummaryThe Asiatic hybrid lily cultivar ‘Akita Petit White’ (APW) is male-sterile with antherless stamens. This trait is advantageous for florists, who otherwise have to remove anthers carefully after the flowers have bloomed. However, unexpectedly, we observed one or two stamens with intact anthers in a few flowers, on fewer than 1% of a total of 400 plants in a field trial of this cultivar, in a horticultural setting. The trial was performed with bulbs that had been stored at –2°C for 9 months. The purpose of the present study was to identify those factors that regulate the expression and reversal of the antherless phenotype in APW lilies. We grew APW plants, from bulbs that had been stored frozen, under three temperature regimes in growth cabinets. Temperature conditions were: high 32°C/25°C (day/night), moderate 25°C/18°C, or low 18°C/11°C; all with a 14 h photoperiod.All stamens in plants which had been grown under the high temperature conditions had intact anthers. Under the moderate temperature conditions, the edges of all filaments, in all plants examined, were yellowish and swollen, resembling undeveloped anthers. Under the low temperature conditions, the antherless phenotype was stable, and no stamens had intact or undeveloped anthers. Pollen from intact anthers, from plants grown under the high temperature conditions, germinated in vitro and produced vegetative and generative nuclei in the normal manner. The yields of viable seeds produced after pollination with these pollen grains were almost equal to those of other Asiatic hybrid lilies (96 – 113 seeds per capsule were obtained with various hybrid combinations). Regulation of the antherless phenotype by temperature is discussed.