Pedro Gómez’s research while affiliated with Andalusian Institute of Agricultural and Fisheries Research and Training and other places

Tomato leaf curl New Delhi virus (ToLCNDV, family Geminiviridae, genus Begomovirus) is a whitefly-transmitted virus that causes widespread damage in Cucurbitaceae and Solaneceae crops worldwide. The Spanish strain, ToLCNDV-ES, affects mainly cucurbit crops and has spread through the Mediterranean basin since its first detection in 2013 in the south of Spain. The control of the virus has been based on the adoption of measures to control the vector, which have not been sufficient to reduce production losses. Therefore, the identification of key genes for ToLCNDV resistance is essential for the development of resistant plants. Regarding genetic control of resistance in cucurbit crops, one major locus on chromosome 11 and two additional regions in chromosomes 12 and 2 of C. melo linked to ToLCNDV resistance have been described recently. Concerning C. moschata, a major QTL was also identified on chromosome 8 that resulted in synteny with a QTL on chromosome 11 of C. melo. In this work, we investigated the molecular basis of ToLCNDV resistance in contrasting accessions of C. melo and C. moschata by transcriptional characterization of 10 different candidate genes controlling host factors related to proviral or antiviral mechanisms. Two proviral factor genes, ARP4 in C. melo and SYTA in C. moschata, showed clear differences in expression levels when the susceptible and resistant accessions were compared. The knowledge of proviral factors associated with resistance could be used to screen an active mutagenesis TILLING platform. This is the case of C. pepo, in which no ToLCNDV resistance has been described to date. The relationship between the regulation of the genes ARP4 and SYTA, as well as the genome position of the described loci related to ToLCNDV resistance, is also discussed.

Pisum sativum L. ssp. arvense, is colloquially called tirabeque or mangetout because it is eaten whole; its pods are recognized as a delicatessen in cooking due to its crunch on the palate and high sweetness. Furthermore, this legume is an important source of protein and antioxidant compounds. Quality control in this species requires the analysis of a large number of samples using costly and laborious conventional methods. For this reason, a non-chemical and rapid technique as near-infrared reflectance spectroscopy (NIRS) was explored to determine its physicochemical quality (color, firmness, total soluble solids, pH, total polyphenols, ascorbic acid and protein content). Pod samples from different cultivars and grown under different fertigation treatments were added to the NIRS analysis to increase spectral and chemical variability in the calibration set. Modified partial least squares regression was used for obtaining the calibration models of these parameters. The coefficients of determination in the external validation ranged from 0.50 to 0.88. The RPD (standard deviation to standard error of prediction ratio) and RER (standard deviation to range) were variable for quality parameters and showed values that were characteristic of equations suitable for quantitative prediction and screening purposes, except for the total soluble solid calibration model.

The study of fruit development in zucchini via gene expression has proven to be applicable in breeding programs. Phenotypic and transcriptomic studies of fruit set and parthenocarpy have been previously developed and some relevant genes have been reported. From these studies, three genotypes (MUCU-16, Whitaker, and Cavili) and six genes (CpAUX22, CpIAA4, CpIAMT-1, CpPIN5, CpCYCD6-1, and CpEXPLB1) were selected. The expression of these genes was analyzed in each genotype under three different treatments (pollination, auxin-treatment and non-treatment) during one week post anthesis. Also, a phenotyping analysis was conducted. The different nature of the samples and the genes selected allowed associations between different fruit traits and fruit development stages. There was a rapid response of CpAUX22 and CpIAA4 to the auxin treatment. Also, these genes and the CpIAMT-1 became more overexpressed in pollinated samples over time. The CpPIN5 gene increased its expression over time in all genotypes while CpCYCD6-1 was overexpressed in the early stages of fruit development in all samples. The CpEXPLB1 was highly up-regulated in non-treated samples, suggesting a relationship with fruit abortion. The overexpression of CpAUX22 and the non-overexpression of CpEXPLB1 in early stages may be associated with fruit growth in zucchini.

Cucurbita species can be affected by soil-borne pathogens, such as Phytopthora capsici and Fusarium solani f. sp. cucurbitae (Fsc). Diverse commercial and conserved lines of Cucurbita spp. were tested. C. pepo subsp. pepo genotypes showed the highest susceptibility to both pathogens. The tolerance to P. capsici and Fsc was then screened in a zucchini mutant population. Two M3 mutant lines (Cp107 and Cp116) with a high occurrence of tolerant individuals to Phytophthora capsici were obtained from a screening of 160 M2 mutant lines. The M3 lines presented higher tolerance than the background MUCU-16. Furthermore, in the inoculated samples, both mutants overexpressed CpDEF and expressed more CpPAL and CpChiIV than the susceptible control. It has been previously shown that this expression pattern could be associated with tolerance in the P. capsici - Cucurbita spp. pathosystem. The M3 lines obtained could be applied in breeding programs, as they are likely to be compatible with the highly susceptible C. pepo subsp. pepo genotype.

Phytophtora capsici causes major diseases in cucurbit crops worldwide. In this study, we inoculated this pathogen into Cucurbita pepo subsp. pepo susceptible MUCU-16 and C. moschata tolerant M63. The gene expression of plant pathogenesis-related proteins chitinase (CpChiIV), lignin-forming peroxidase (CpLPOX), and defensin (CpDEF) and hormone-related enzymes salicylic acid (CpPAL) and ethylene (CpACO) was analyzed for two weeks post-inoculation in root and crown tissues. Differentially expressed genes were found between genotypes, tissues, days post-inoculation, and inoculated/non-inoculated samples. After inoculation, CpPAL and CpChiIV (crown) were downregulated in MUCU-16, while CpLPOX and CpDEF were upregulated in M63. In inoculated samples, higher expression changes were presented on days 10–14 than on day 3 for CpACO, CpLPOX, and CpDEF genes. Overexpression was higher for CpDEF compared to the other tested genes, indicating good suitability as a marker of biotic stress. The overexpression of CpDEF was higher in crown than in roots for both inoculated genotypes. The basal expression of CpPAL and CpDEF was higher in MUCU-16, but after inoculation, CpPAL and CpDEF gene expression were higher in M63. These changes suggest an association between CpDEF upregulation and tolerance, and between CpPAL downregulation and susceptibility.

Appropriate fertigation management plays an important role in increasing crop quality and economizing water. The objective of the study was to determine the effects of two fertigation treatments, normal (T100) and 50% sustained deficit (T50), on the physico-chemical quality of legumes. The determinations were performed on the edible parts of peas, French beans and mangetout. The trials were conducted in a protected cultivation certified organic farm. The response of legumes to the treatments varied between the cultivars tested. The fertigation treatments had a significant effect on the morphometric traits (width for mangetout and French bean; fresh weight for French bean; seed height for Pea cv. Lincoln). The total soluble solids and citric acid content have been shown to be increased by low soil water availability (T50) for mangetout. Fertigation treatments did not significantly affect the antioxidant compounds (total phenolic and ascorbic acid), minerals and protein fraction contents of legumes studied. Regarding legume health benefits, the most prominent cultivars were BC-033620 pea and French bean because of their high total phenolic (65 mg gallic acid equivalent 100 g−1 fresh weight) and ascorbic acid content (55 mg ascorbic acid 100 g−1 fresh weight), respectively. The results expand our knowledge concerning the nutraceutical quality and appropriate cultivation methods of legumes in order to make the system more sustainable and to encourage their consumption.

Although Cucurbita pepo is one of the most variable species of the plant kingdom, Zucchini morphotype has undergone intensive breeding that has led to a narrow genetic base making the crop vulnerable to pest and diseases. This vulnerability makes the knowledge of resistance genes of utmost importance. In this study, a data mining search of Zucchini summer squash genome database was conducted to identify and annotate members of the NBS-encoding gene family. In order to characterize the retrieved genes in detail, they have been studied in the bases of phylogenetic relationships, structural diversity, conserved protein motifs, gene duplications and promoter region analysis. Our study shows that the NBS-encoding gene family is relatively small in Zucchini (34 members, which are separated into non-TIR- and TIR-NBS-LRR subfamilies) with a significantly lower number of R-genes than in other species. Duplications have not played a major role in the expansion of this type of genes in C. pepo. Among the cis-regulatory elements presented in these sequences, six motifs are over-represented. These elements were reported to be involved in pathogens or plant stress induced responses. These results will contribute to the identification, isolation and characterization of candidate R-genes, thereby providing insight into NBS gene family evolution in the species.

The main economic value of the Cucurbita species resides in the consumption of its immature fruits as vegetables, commonly known as summer squashes. The beneficial health effects of summer squash are attributed to their bioactive compounds, contributing positively to the daily nutritional intake and also protecting against some diseases, including diabetes, cardiovascular diseases, accelerated aging, and some types of cancer. This chapter provides an overview of nutritional composition, antioxidant properties, as well as the health benefits of the eight summer squash morphotypes (pumpkin, vegetable marrow, cocozelle, zucchini, acorn, scallop, crookneck, and straightneck). We also highlight the influence of ripening stage, agronomic conditions, and environmental variation that can contribute to increase desirable summer squash attributes as well as the potential contribution to the required daily intake by compiling the most recent works found in the literature on this subject.

Background: Zucchini fruit set can be limited due to unfavourable environmental conditions in off-seasons crops that caused ineffective pollination/fertilization. Parthenocarpy, the natural or artificial fruit development without fertilization, has been recognized as an important trait to avoid this problem, and is related to auxin signalling. Nevertheless, differences found in transcriptome analysis during early fruit development of zucchini suggest that other complementary pathways could regulate fruit formation in parthenocarpic cultivars of this species. The development of next-generation sequencing technologies (NGS) as RNA-sequencing (RNA-seq) opens a new horizon for mapping and quantifying transcriptome to understand the molecular basis of pathways that could regulate parthenocarpy in this species. The aim of the current study was to analyze fruit transcriptome of two cultivars of zucchini, a non-parthenocarpic cultivar and a parthenocarpic cultivar, in an attempt to identify key genes involved in parthenocarpy. Results: RNA-seq analysis of six libraries (unpollinated, pollinated and auxin treated fruit in a non-parthenocarpic and parthenocarpic cultivar) was performed mapping to a new version of C. pepo transcriptome, with a mean of 92% success rate of mapping. In the non-parthenocarpic cultivar, 6479 and 2186 genes were differentially expressed (DEGs) in pollinated fruit and auxin treated fruit, respectively. In the parthenocarpic cultivar, 10,497 in pollinated fruit and 5718 in auxin treated fruit. A comparison between transcriptome of the unpollinated fruit for each cultivar has been performed determining that 6120 genes were differentially expressed. Annotation analysis of these DEGs revealed that cell cycle, regulation of transcription, carbohydrate metabolism and coordination between auxin, ethylene and gibberellin were enriched biological processes during pollinated and parthenocarpic fruit set. Conclusion: This analysis revealed the important role of hormones during fruit set, establishing the activating role of auxins and gibberellins against the inhibitory role of ethylene and different candidate genes that could be useful as markers for parthenocarpic selection in the current breeding programs of zucchini.