Abstract:

To realize the accurate molecular identification for fruit shape,we performed following study. Based on resource advantage of“National mid-term gene-bank for watermelon and melon”and re-sequencing platform,two segregation populations,including an F₂ and an BC₁P₁,has been constructed to unravel the functional genetic variation for fruit shape in watermelon. A 159 bp InDel（Insertion/Deletion）and one non-synonymous SNP led round fruit to long fruit in watermelon,respectively. Moreover,the SNP located on the genomic region of 159 bp InDel. One CAPS marker,Markersun,was developed and genotyped in F₂ and BC₁P₁ populations,and a core germplasm resources including 128 inbred lines. The marker Markersun showed InDel and SNP polymorphism in F₂ and BC₁P₁ populations,respectively,and totally cosegregated with fruit shape variation in both populations. The marker Markersun both showed InDel and SNP polymorphism in core germplasm resources and totally cosegregated with fruit shape variation. The results were reconfirmed based on resequencing data of 196 germplasm resources in watermelon. Moreover,genotype analysis of different type of germplasms found that long fruit caused by SNP occurred earlier and inherited independently;while long fruit caused by 159 bp InDel occurred during domestication of cultivated watermelon. The current research firstly realized accurate molecular identification of watermelon fruit shape. At the same time,two functional variations of fruit shape were excavated and corresponding marker was developed to accurately identify watermelon fruit shape. These results will provide technical support and targets for the functional verification of fruit shape traits,and accelerate the study of the functional mechanism for fruit shape gene in watermelon.

Key words: Citrullus lanatus, fruit shape, functional molecular marker, core germplasm, accurate identification