Morphological and molecular diversity in a germplasm collection of seed pumpkin

Seed pumpkin is an important economic crop grown in Heilongjiang Province, China that comprises distinct cultivars of Cucurbita maxima and C. pepo. However, little is known about the genetic diversity of seed pumpkin. Morphological and molecular characterizations were used to investigate the genetic diversity and genetic relationships within a germplasm collection that included 38 Chinese and 28 Russian seed cultivars of C. maxima, and 10 Chinese seed genotypes of C. pepo. The most variable morphological characters were all usually associated with the fruit. Thirty-five SSR markers yielded a total of 85 amplified DNA fragments, of which 85.89% were polymorphic, indicating a high degree of genetic diversity. The information provided by the SSR markers was agreed with the morphological diversity. Principal components analysis (PCA), principal coordinates analysis (PCO), and UPGMA clustering clearly distinguished the accessions based on species and geographic regions for both morphological and molecular characterizations. This indicated that genetic divergence has occurred between germplasm from China and that from Russia. On the other hand, geographical location also appeared to have affected genetic diversity due to adaptation of the plants to the different environments. This finding suggested that molecular information on genetic relationships in combination with morphological characteristics would serve to (1) improve the classification system of seed pumpkin cultivars in cultivation for germplasm conservation, (2) enhance the economic value of seed pumpkin.

► We analyzed the genetic diversity in 76 seed accessions of C. maxima and C. pepo.
► The germplasm collection included diverse accessions grown in China and Russia.
► We used morphological and simple sequence repeat (SSR) data to estimate diversity.
► All clustering methods clearly separated the accessions of the two species.
► Clustering also reflected the geographical origins of the seed pumpkin accessions.