Abstract
Cucurbita maxima Duchesne squash and pumpkins are cultivated world-wide. Cucurbita maxima fruits are produced for fresh market and are valuable for food processing. Therefore, fruit characteristics and yield are the traits of high economic importance for breeders. To date, the genetic basis of fruit-associated traits in C. maxima have been poorly understood. In the present study, we evaluated fruit-associated traits and conducted quantitative trait locus (QTL) analysis using recombinant inbred lines (RILs) derived from a cross of two inbred lines with different fruit morphotypes. Phenotypic data for nine fruit traits (earliness, weight, number per plant, yield per plant, length and diameter, shape index, flesh thickness, sucrose content and dry matter content) were collected for RILs in two open-field experiments. Pairwise analysis of the phenotypic data revealed correlations among the fruit and yield-associated traits. Using a previously developed genetic map, we identified 26 QTLs for eight traits. The QTLs were found in 10 locations on eight chromosomes of C. maxima. The QTLs were detected across experiments and explained up to 41.4% of the observed phenotypic variations. Major-effect QTLs for multiple fruit-associated traits were clustered on chromosome 4, suggesting that this genomic region has been under selection during diversification and/or domestication of C. maxima.
Highlights
Cucurbita maxima Duchesne originates from South America and has spread worldwide in the post-Columbian era
Major-effect quantitative trait locus (QTL) for multiple fruit-associated traits were clustered on chromosome 4, suggesting that this genomic region has been under selection during diversification and/or domestication of C. maxima
This study provides us with novel data about QTLs associated with economically important traits in C. maxima and it contributes to the fine mapping and identification of the genes responsible for fruit traits in this cucurbit species
Summary
Cucurbita maxima Duchesne originates from South America and has spread worldwide in the post-Columbian era. Cucurbita maxima is an annual species with indeterminate plant growth and a predominantly monoecious sexual system. It is an allotetraploid species with chromosome number. C. maxima is one of 10 Cucurbitaceae species of worldwide economic importance, and together with C. pepo and C. moschata, it is one of the three most important Cucurbita species [3,4,5,6]. C. maxima is recognized as the most diverse species of Cucurbita and its fruits are characterized by great morphological variation and differences in size, shape and peel color [7]
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