An APETALA3 MADS-box linked SCAR marker associated with male specific sex expression in Coccinia grandis (L). Voigt

• RAPDs were screened to detect a male specific sex fragment CgMSM in C. grandis.
• SCAR marker (CgY1) designed from it amplified an 829 bp fragment in males.
• Southern blotting confirmed it as a single copy locus only in male genome.
• CgY1 showed high homology with MADS-box domain of Apetalla3-MADS box gene.
• CgY1 accurately detected 11 males and 6 females of C. grandis with unknown sex.

Coccinia grandis L. (Family – Cucurbitaceae), a perennial dioecious herb with heteromorphic sex chromosomes has the quality of a model plant for analysis of sexual evolution in angiosperms. Yet, little is known about the physical side, genetic orientation and substitution behavior of key gender-defining factors in this important plant species. Screening of genomic DNA with RAPD primers was used for sex diagnosis and gender specificity of C. grandis in this study. Bulk analyses of pooled DNA from male and female genotypes resulted in the isolation of a putative male specific sex marker CgMSM. A sequence characterized amplified region (SCAR) marker CgY1 designed from CgMSM amplified an 829 bp fragment in the male C. grandis but not in the female plants. Southern blotting confirmed it as a single copy locus in the male genome. Further, the CgY1 marker accurately identified 11 male and 6 female genotypes from 17 individuals of C. grandis with unknown sex. Sequence homology revealed high similarity between CgMSM (CgY1) and the putative MADS-box domain of the APETALA3 (AP3) MADS-box gene which is responsible for development of petals and stamens in flowering plants. Thus, the SCAR marker CgY1 could be used as an efficient tool for early sex identification in C. grandis and forms the basis for characterization of genes associated with evolutionary pathways in sexual dimorphism.