Cucurbita maxima Duch. is one of the most morphologically variable cultivated species. The Center for Conservation and Breeding of the Agricultural Diversity (COMAV) holds a diverse germplasm collection of the Cucurbita genus, with more than 300 landraces of this species. Morphological and molecular characterization are needed to facilitate farmer and breeder use of this collection. With this aim, the morphological variation of a collection of 120 C. maxima accessions was evaluated. The majority of these accessions originated from Spain, which has acted as a bridge since the 16th century for spreading squash morphotypes between the Americas and Europe. South American landraces (the center of origin of this species) were also included. Eight morphological types were established based on this characterization and previous intraspecific classifications. A subset of these accessions, selected from these classification and passport data, was employed for molecular characterization. Two marker types were used; sequence related amplified polymorphism (SRAP), which preferentially amplifies open reading frames (ORF), and amplified fragment length polymorphism (AFLP). In the main, SRAP marker analysis grouped accessions in accordance to their type of use (agronomic traits) and AFLP marker analysis grouped accessions as to their geographical origin. AFLP marker analysis detected a greater genetic variability among American than among Spanish accessions. This is likely due to a genetic bottleneck that may have occurred during the introduction of squash into Europe. The disparity of the results obtained with the two markers may be related to the different genome coverage which is characteristic of each particular marker type and/or to its efficiency in sampling variation in a population.
María Ferriol, Belén Picó, and Fernando Nuez
Andrés Cáceres, Gorka Perpiña, María Ferriol, Belén Picó, and Carmina Gisbert
Francisco Javier Palomares-Rius, Ana Garcés-Claver, María Belén Picó, Cristina Esteras, Fernando Juan Yuste-Lisbona, and María Luisa Gómez-Guillamón
Ana Carolina de Assis Dantas, Ioná Santos Araújo Holanda, Cristina Esteras, Glauber Henrique de Sousa Nunes, and Maria Belén Picó
Melon (Cucumis melo) is one of the most important horticultural crops in Brazil. A set of 40 melon landraces representing a northeastern Brazilian variation was agronomically evaluated with 13 morphological traits and molecularly with 13 simple sequence repeat markers and compared with a set of 21 reference accessions of diverse taxonomic and geographic origins. Brazilian accessions were highly variable for seed, flowering time, fruit, and yield-related traits. However, most of them shared a monoecious sex type, a climacteric ripening behavior, and fruit that were low to medium in sugar with a high acid content, characteristics in accordance with those of Asian melons belonging to Momordica, Flexuosus, and Chate, and Far-Eastern Makuwa and Chinensis melon groups. Molecular analysis confirmed the genetic similarity of the Brazilian landraces to reference accessions from India, the Far East, and the Middle East belonging to those botanical groups. Momordica, Makuwa, and Chinensis melons are rarely found as landraces outside of this area thus suggesting that these landraces were introduced into Brazil from these regions. Our molecular results also support a high genetic diversity in the Brazilian collection [polymorphism information content (PIC) = 0.43], which is only slightly lower than that of the references (PIC = 0.59) that include most of the main horticultural groups of the two C. melo subspecies. This study shows that in Brazil, there is currently a large variability of this species maintained in the form of landraces, which are a potentially useful resource for breeding melons.