Identification of three genomic regions and underlying candidate genes controlling the high level of resistance to ToLCNDV derived from a wild melon. SNP markers appropriated for MAS management of resistance. Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus that severely affects melon crop (Cucumis melo) in the main production areas of Spain since 2012. In this work, we evaluated the degree of resistance of four accessions (two belonging to the subsp. agrestis var. momordica and two to the wild agrestis group) and their corresponding hybrids with a susceptible commercial melon belonging to the subsp. melo (Piel de Sapo, PS). The analysis using quantitative PCR (qPCR) allowed us to select one wild agrestis genotype (WM-7) with a high level of resistance and use it to construct segregating populations (F and backcrosses). These populations were phenotyped for symptom severity and virus content using qPCR, and genotyped with different sets of SNP markers. Phenotyping and genotyping results in the F and BC1s populations derived from the WM-7 × PS cross were used for QTL analysis. Three genomic regions controlling resistance to ToLCNDV were found, one major locus in chromosome 11 and two additional regions in chromosomes 12 and 2. The highest level of resistance (no or mild symptoms and very low viral titer) was obtained with the homozygous WM-7WM-7 genotype at the major QTL in chromosome 11, even with PSPS genotypes at the other two loci. The resistance derived from WM-7 is useful to develop new melon cultivars and the linked SNPs selected in this paper will be highly useful in marker-assisted breeding for ToLCNDV resistance in melon.

Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus (family Geminiviridae) first reported in India and its neighbouring countries. ToLCNDV severely affects zucchini crop (Cucurbita pepo) in the main production areas of Southern Spain since 2012. This emerging begomovirus is a serious threat to this and other cucurbit crops. Breeding resistant cultivars is the most promising method for disease control, but requires the identification of sources of resistance in the Cucurbita genus. In this work, we screened for ToLCNDV resistance a large collection of Cucurbita spp. accessions, including landraces and commercial cultivars of the main cultivated species, C. pepo, Cucurbita moschata and Cucurbita maxima and wild species. The screening was performed using mechanical and whitefly inoculation. The level of resistance was assessed by scoring symptom severity and by measuring the virus content with quantitative polymerase chain reaction in selected genotypes. Diversity in the response was observed within and among species. Severe symptoms and high viral amounts were found at 30 days after mechanical and whitefly inoculation in C. pepo, in all accessions belonging to the Zucchini morphotype and to other morphotypes of both subspecies, pepo and ovifera, and even in the wild relative Cucurbita fraterna. C. maxima was also highly susceptible. This species showed characteristic symptoms of leaf decay and intense yellowing, different from those of mosaic, curling and internode shortening found in C. pepo. The only species showing resistance was C. moschata. Four accessions were symptomless or had some plants with only mild symptoms after three independent rounds of mechanical inoculation with different inoculum sources. Two of them also remained symptomless after virus inoculation with viruliferous whiteflies. ToLCNDV was detected in these asymptomatic accessions at 15 and 30 days post inoculation, but viral amounts were much lower than those found in susceptible genotypes, suggesting a high level of resistance. The symptoms in the susceptible accessions of this species were also different, with a characteristic leaf mottling, evolving to a severe mosaic. The newly identified C. moschata resistant accessions are good candidates for breeding programmes to avoid the damage caused by ToLCNDV.

Sáez et al. ToLCNDV Resistance in C. moschata of melon, previously described as responsible of ToLCNDV resistance. Common genes in the candidate regions of both cucurbits, with high-or moderate-impact polymorphic SNPs between resistant and susceptible C. moschata accessions, are interesting to study the mechanisms involved in this recessive resistance.

A total of 27% of manic patients showed mixed features. Groups differed regarding clinical characteristics, course of illness, psychosocial functioning, prescribed treatment and symptom progress. Depressive symptoms in mania should be routinely assessed and considered to guide treatment.