Identification of Fruit-Associated QTLs in Winter Squash (Cucurbita maxima Duchesne) Using Recombinant Inbred Lines

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.

QTL Mapping for Pumpkin Fruit Traits Using a GBS-based High-density Genetic Map

“…In the present study, FW exhibited transgressive segregation and was positively correlated with FL, FD, SCS, and FTH, respectively. Similar results were also observed in C. maxima (Kazminska et al 2020). In the previous reports, 1 and 6 QTL related to FW was detected in pumpkin and C. maxima (Hashimoto et al 2020), Kazminska et al 2020), respectively.…”

“…Similar results were also observed in C. maxima (Kazminska et al 2020). In the previous reports, 1 and 6 QTL related to FW was detected in pumpkin and C. maxima (Hashimoto et al 2020), Kazminska et al 2020), respectively. In the present study, 4 QTLs were detected for FW, and two of them were co-localized with the SCS and FTH related QTLs, respectively.…”

“…In the present study, 3 QTLs for FL and 5 QTLs for FD were detected in pumpkin. Of them, a QTL for FL locating on chromosome 14 was overlapped with the one detected in C. maxima, while no consensus QTLs for FD were observed between pumpkin and C. maxima (Kazminska et al 2020). In addition, no colocation of QTLs for FL and FD were found in the present study, suggesting that elongation of fruit and increase of diameter might be under different genetic mechanisms in pumpkin.…”

“…Due to lack of the physical position information in pumpkin reference genome, it was di cult to compare the above-mentioned QTLs with the other studies. Moreover, 3 and 2 QTLs were identi ed for FL and FD in C. maxima, respectively (Kazminska et al 2020). In the present study, 3 QTLs for FL and 5 QTLs for FD were detected in pumpkin.…”

Genetic Mapping and Identification of the Candidate Gene for White Seed Coat in Cucurbita maxima

“…Improvements of whole genome sequences and high-density genetic maps have promoted the precision of genomic data in Cucurbita and support a better foundation for the research and application of candidate genes in Cucurbita species [ 36 , 37 , 38 , 39 , 40 , 41 ]. With effective utilization of molecular markers and genetic map resources, QTLs for many agronomic traits and candidate genes have been identified and applicated accordingly in breeding selection [ 42 , 43 , 44 , 45 , 46 ]. Some QTLs of seed trait such as seed size, seed width, and seed yields have been identified in Cucurbita maxima and candidate genes are precited [ 10 , 47 ].…”