The cultivar ‘Fuentes de Ebro’ is a long-day onion grown in the northeast of Spain, which is characterized by its succulence and low pungency. However, to match the market demand the size, pungency, and storability need to be improved. We have evaluated these quality-related bulb traits in 15 grower’s open-pollinated lines of this cultivar. Phenotypic variation observed for bulb weight, size and soluble solids content was significantly affected by location, growing season and line, while pungency depended on line and plot location. We found higher levels of genetic variation for bulb size and pungency than for soluble solids content, and significant phenotypic correlations indicated that milder onion tend to show larger size and lower soluble solids content. After one cycle of selection, we have obtained progeny with significantly lower pungency levels, and therefore, we estimated a realized heritability of 0.67. As conclusion, it is feasible to obtain a sweet cultivar after some selection cycles in the ‘Fuentes de Ebro’ onion, although considering indirect consequences in size and soluble solids conten

In total, 139 Cucumis melo accessions were evaluated for resistance to races 0, 1, and 2 of Fusarium oxysporum fsp. melonis and 127 accessions were evaluated for resistance to races 1 and 2 of Sphaerotheca fuliginea. In addition, seven C. melo wild relatives were also tested. Artificial inoculations were performed and plants were scored for presence or absence of symptoms. The screening revealed that sources of natural resistance to these fungi are limited. However, several sources of resistance were found in C. melo accessions. Thus, the accession `CUM-334' from Tajikistan has shown resistance to the three races of F. oxysporum fsp. melonis, behaving similarly to the melon inbred line `MR1'. Two accessions of C. melo var. conomon, `CUM-190' and `Shiroubi Okayama', from Japan, were resistant to races 0 and 1 and twelve accessions were resistant to races 0 and 2. Intra-specific variability for resistance to powdery mildew in C. melo was found to be poor. Nevertheless, six Spanish cultivars and the accessions `TGR-1551', `CUM-313', and `CUM-129' were resistant to races 1 and 2 of S. fuliginea.

Onions are the second most-valuable vegetable in the world. Despite its global culinary and economic significance, the knowledge of genetic diversity and resources is limited. The aim of this study was to morphologically and physico-chemically characterize eighty-six onion landraces from Spain, part of the secondary Mediterranean Centre of diversity. The evaluated traits in the bulb included: weight, shape, firmness, soluble solids content (SSC), pungency and sugars content (glucose, fructose and sucrose). The results evidenced a great variability in all the evaluated traits. Correlations were significant between pungency and SSC (r = 0.34), firmness (r = 0.32), and sucrose content (r = 0.34); between fructose and glucose contents (r = 0.79); between sucrose content and SSC (r = 0.57); between SSC and weight (r = -0.35); between fructose and sucrose contents (r = -0.22); and between weight and sucrose content (r = -0.43). The combination of cluster and discriminant analyses resulted in a classification into four clusters (95.3% fit). Cluster 1 is represented by firm, pungent and large-sized bulbs; cluster 2 consists of large-sized, mild and sweet onions; cluster 3 is constituted by pungent, high-SSC and small-sized bulbs and cluster 4 is made up by elongated bulbs. The variability in important agronomical traits found point out that these onion accessions could be candidates for future breeding programs. In addition, the clustering could make the initial plant material selection easier and the correlations among the evaluated traits found could help to establish adequate selection strategies.Additional key words: cluster analysis; firmness; genetic diversity; pungency; soluble solids; sugars. Resumen Caracterización de los recursos genéticos de cebolla (Allium cepa L.) procedentes del centro secundario de diversificación de EspañaLa cebolla es el segundo cultivo hortícola a nivel mundial. Sin embargo, el conocimiento sobre los recursos y la diversidad genética de esta especie es limitado. Por ello, el objetivo del presente trabajo consistió en el estudio morfológico y físico-químico de una colección de 86 cultivares de cebolla procedentes de España (que forma parte del centro secundario de diversificación). Los caracteres evaluados en el bulbo incluyeron: peso, forma, firmeza, contenido en sólidos solubles (SSC), pungencia y contenido en azúcares (glucosa, fructosa y sacarosa). Los resultados evidenciaron una gran variabilidad en todos los caracteres evaluados. Las correlaciones fueron significativas entre la pungencia y SSC (r = 0,34), firmeza (r = 0,32) y contenido en sacarosa (r = 0,34); entre contenido en fructosa y glucosa (r = 0,79); entre contenido en sacarosa y SSC (r = 0,57); entre SSC y peso (r = -0,35); entre contenido en fructosa y sacarosa (r = -0,22) y entre el peso y contenido en sacarosa (r = -0,43). El análisis discriminante dio lugar a la formación de cuatro grupos con un ajuste del 95,3%. El grupo 1 está formado por bulbos grandes, firmes y picantes, el grupo 2 por cebollas grandes, su...

Melon necrotic spot virus (MNSV) has been found affecting melon (Cucumis melo L.) crops. At present the only known resistance in melon is controlled by a single recessive gene, nsv. The presence of nsv in a melon genotype has been correlated with the lack of necrotic lesions on the mechanically inoculated cotyledons. Thus, in a screening program for MNSV resistance, melon genotypes that developed necrotic lesions in the inoculated cotyledons were discarded. However, in this paper we show that some melon accessions mechanically inoculated with MNSV do develop local necrotic lesions, therefore showing the absence of the gene nsv, but fail to develop the systemic symptoms typical of diseased plants under the screening conditions. In some of these accessions the influence of the temperature on the development of systemic symptoms was studied. The results showed that, depending on the accession, temperatures under 25 or 20 °C enhanced the systemic development of the disease. One of the tested varieties, `Doublon', did not develop systemic symptom at any of the tested temperatures (15, 17.5, 20, 22.5, 25, 27.5, and 30 °C). In this variety, the lack of systemic symptoms was correlated to the lack of virus infection of these tissues based upon ELISA results. MNSV was not detected in the uninoculated parts of the plant, and seems to remain confined to the local lesions produced on the cotyledons following the mechanical inoculation. Restriction of viral multiplication and/or cell-to-cell movement could explain the pattern of viral distribution in this variety. This reaction was observed in the `Doublon' plants mechanically inoculated with each of five isolates of MNSV tested, including an isolate that overcomes the nsv gene resistance.

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