Production of haploid embryos and plants in Iranian melon (Cucumis melo L.) through irradiated pollen-induced parthenogenesis.

Abstract

Abstract The irradiated pollen technique (IPT) is the most successful haploidization technique within Cucurbitaceae. The influence of gamma-ray doses (250, 350, 450 and 550 Gy), genotypes and stage of development of embryos obtained by IPT on the induction of haploid embryos were studied in several Iranian melon cultivars as well as their hybrids with alien cultivars. Female flowers were pollinated using pollen that had been irradiated with gamma rays. Different shapes and stages of embryos were excised 21-25 days after pollination and cultured on E20A medium. Direct culture, liquid culture and integrated culture methods were used; integrated culture and liquid culture methods showed advantages in increasing the efficiency of haploid plant production in melon breeding programmes. Results revealed that 550 Gy of gamma irradiation was successful in inducing parthenogenesis and fruit development, whereas lower irradiation doses were not effective in inducing haploid embryos. The percentages of embryos per seed were the highest in 'Samsoori' (1.2%) and 'Saveh' (1.1%) cultivars. Some of the heart-shaped and cotyledon-shaped embryos developed into haploid plants. In total, 52 parthenogenic melon plantlets were recovered from 274 embryos via IPT. Production of haploid embryos and haploid plants was strongly influenced by gamma-ray dose, embryo stage and genotype. Indirect methods and chromosome counting performed on the root cells of regenerated plants showed that these plants were haploid (n = x = 12).