Efficiency of SSR markers for determining the origin of melon plantlets derived through unfertilized ovary culture

Abstract

The effects of temperature pre-treatment, thidiazuron, naphthaleneacetic acid, and 6-benzylaminopurine on in vitro gynogenic plant production from un-pollinated melon (Cucumis melo L.) ovaries were investigated. Simple sequence repeat (SSR) marker analysis was conducted to identify the homozygous diploid individuals. The temperature pre-treatment (4°C) for 4 days increased embryo formation frequency (63.3%) significantly. Addition of thidiazuron (0.04 and 0.02 mg/l) in the induction medium significantly increased the number of responding ovaries (46.6%, 65.83%), respectively. The maximum number of plantlet regeneration (22.5%) was achieved by culturing the ovary derived embryos on Murashigue and Skoog medium (MS medium) supplement with 0.6 mg/l 6-benzylaminopurine. Spontaneous doubled haploids originated directly through embryogenesis were subjected to genetic analysis using SSR molecular marker with 23 primers pair for homozygosity. SSR markers with microsatellite CMGA172, confirmed that the alleles in the parental material were also present in the gynogenic plantlets, but amplified only two alleles as compared to four alleles of the heterozygous parent material at same locus. Therefore these regenerated plantlets were consider homozygous and produced through a process of gametophytic embryogenesis.