Melon: a good model for climateric non-climateric behavior: the variation of this trait in a germplasm collection

Melon (Cucumis melo L. Cucurbitaceae) represents one of the most variable species within the genus Cucumis as well as among the other cultivated plants. Moreover it is a key species in order to study ethylene involvement in ripening because several climacteric and non climacteric accessions are available. A core collection of 176 melon accessions including wild relatives, feral types, landraces, breeding lines and commercial cultivars from 54 countries was used for this study. This collection was selfed, genotyped with AFLP and SNP markers and extensively phenotyped for plant and fruit traits at COMAV. The abscission layer formation has been used as a practical method for phenotyping this trait in the collection. The PCA approach based on SNP markers confirmed the presence of two clear subspecies; melo and agrestis. Among agrestis, African wild types, can be easily distinguished from far eastern conomon along PC1, while PC2 separated Indian momordica from the rest. Melo subspecies comprises five groups distributed along PC1 and PC2. A high degree of variability for abscission layer formation has been observed among the groups indicating it is a good mean for the genetic study of climacteric and non-climateric ripening.