Parthenogenesis and apogamy in unpollinated ovary culture of leek (Allium tuberosum Roxb.)

Abstract

Leek (Allium tuberosum) is highly heterozygous owing to asynchronous maturity of the androecium and gynoecium. Haploid induction is pertinent to overcome this impediment in leek breeding. In this study, unpollinated ovaries of leek were float cultured on liquid medium to induce development of haploid plantlets. On Murashige and Skoog media supplemented with 3–12% sucrose, 0–0.4 mg/L−1 2,4-dichlorophenoxyacetic acid (2,4-D), and 0–2 mg/L−1 zeatin (Zt), many ovules produced parthenogenic and/or apogamic embryos. Microscopic observation confirmed the embryos originating from the egg and egg-like antipodal cell. The optimal concentration of the medium components is 0.1 mg/L−1 2,4-D, 0.5 mg/L−1 Zt and 9% sucrose, in which 58.3% ovules produced embryos. This method will be useful in haploid breeding of leek on account of the high frequency of autonomous haploid embryogenesis. Apogamy of antipodal cells is few to occur naturally in higher plants, therefore this report is the confirmation of antipodal apogamy. The origin and development of parthenogenesis and apogamy in leek are discussed.