Genetic Mapping Reveals a Flower-and-Tendril Mutation (Clftm) in Watermelon (Citrullus lanatus L.)

In the study of plant organogenesis, flower development is an outstanding model system. A natural mutation in watermelon was found to be involved in converting both male and female flowers to sepals, and the top of normal tendrils to young leaves. A normal watermelon inbred line and a hybrid line were created through inbreeding of sister-lines for this mutation. We identified a recessive single gene, named Clftm (flower-and-tendril mutation), that controls this mutation. The candidate region was between 3.12 and 4.25 Mb on chromosome 3 according to BSA-seq. Then, several major markers, 56 CAPS markers, 4 SSR markers and 6 SNP markers, were used for fine mapping; the candidate gene was mapped to the 110 kb region on chromosome 3 (4.08–4.19 Mb). Although the locus was delimited to this 110 kb interval, no candidate gene was identified within it. Utilizing the F2 populations and 20 watermelon accessions, an SNP marker was found to be closely linked to watermelon flower-and-tendril mutation. This research provides new insight for future studies on flower development and floral organ formation.