BUSCADOR RECOLECTA

The peach is one of the most important global tree crops within the economically important Rosaceae family. The crop is threatened by numerous pests and diseases, especially fungal pathogens, in the field, in transit, and in the store. More than 50% of the global post-harvest loss has been ascribed to brown rot disease, especially in peach late-ripening varieties. In recent years, the disease has been so manifest in the orchards that some stone fruits were abandoned before harvest. In Spain, particularly, the disease has been associated with well over 60% of fruit loss after harvest. The most common management options available for the control of this disease involve agronomical, chemical, biological, and physical approaches. However, the effects of biochemical fungicides (biological and conventional fungicides), on the environment, human health, and strain fungicide resistance, tend to revise these control strategies. This review aims to comprehensively compile the information currently available on the species of the fungus Monilinia, which causes brown rot in peach, and the available options to control the disease. The breeding for brown rot-resistant varieties remains an ideal management option for brown rot disease control, considering the uniqueness of its sustainability in the chain of crop production.

A sustainable approach to control the incidence of brown rot in pre- and post-harvest management is to select genotypes with high contents of antioxidant compounds and tolerance to Monilinia laxa (Aderh. and Ruhland) Honey. In this study, 68 progenies of the ‘Babygold 9’ × ‘Crown Princess’ population from the EEAD-CSIC breeding program were screened under controlled conditions for a period of 3 years (2013–2015). Susceptibility to brown rot was evaluated after inoculating 20 healthy fruits per genotype with M. laxa. Brown rot incidence, lesion diameter, and colonization extent, as well as the severities of these issues, were calculated after 5 days of incubation. Physicochemical traits, such as fruit firmness and soluble solids content, were also recorded before and after storage. Titratable acidity, pH, and antioxidant composition were measured at harvest. Significant differences were found for pathogenic traits, as well as for contents of vitamin C, total phenolics, flavonoids, and anthocyanins, within genotypes in this population. Negative correlations were also found between the content of phytochemical compounds (such as anthocyanins and total phenolics), as well as disease incidence and severity. Differences in susceptibility to brown rot confirm the genetic variability available in these progeny. This allowed the selection of six genotypes highly resistant to brown rot of M. laxa, with high organoleptic properties and high phenol content, to be introduced in our peach breeding program.

Brown rot, caused by Monilinia spp., provokes pre-and post-harvest damage in peach (Prunus persica (L.) Batsch), which causes an economic impact in the industry. With a view to breeding for increased tolerance to this disease, a screening test based upon artificial fruit inoculation was validated on several parental lines of a peach breeding program during the two-period harvest. In addition, cultivars with different total phenolic contents were included in the two-year study. All physicochemical fruit traits recorded at harvest showed differences among all cultivars. The antioxidant compound content determined using spectrophotometry (to measure ascorbic acid and antioxidant capacity) and UPLC-MS (to measure and identify phenolic compounds) also revealed important differences among all genotypes. The rate of brown rot lesion following fruit inoculation varied widely among cultivars, and it was possible to discriminate between highly and less susceptible cultivars. Cultivars with minimal development of damage were identified as germplasm with the desirable allele combination to increase brown rot tolerance in peach breeding programs. Finally, Pearson’s correlation coefficients (r) between pairs of variables were calculated, searching for any biochemical candidate conferring tolerance. The correlation of phytopathological traits with the antioxidant composition, concerning contents of ascorbic, neochlorogenic, and chlorogenic acids and total polyphenols in fruit, is discussed.

The "Pero de Cehegín"is an ancient local variety of apple grown in Murcia (Spain). In this study, microsatellites markers showed evidence of a unique profile that has never been reported before in other Spanish apple germplasm collections. Five "Pero de Cehegín"clones were evaluated and compared with two commercial apple varieties, "Fuji"and "Golden Delicious", to assess its marketing potential. For this, the physical (weight, height, and width of the fruit, moisture content, firmness, and color of the fruit, among others), and chemical (total soluble solids, total acidity, and maturity index) properties of the fruits were evaluated. In addition, the content of bioactive compounds such as total polyphenol content, total antioxidant activity using the ABTS+, DPPH, and FRAP methods, and the sugar profile were analyzed, and their sensory profile was also evaluated. Physico-chemical differences were found within the "Pero de Cehegín"clones and between the commercial varieties. "Pero de Cehegín"had a high firmness, high total soluble solids, very low total acidity, high FRAP antioxidant capacity, and more sucrose content in comparison with "Fuji"and "Golden Delicious". These distinctive characteristics and the good appearance of the fruit make this variety a marketable product that will increase the offering of traditional, local, but underutilized fruit varieties.

One of the diseases that has the greatest negative effect on peach production is brown rot, produced by the fungus, Monilinia spp. The way to diminish this disease is the selection of genotypes with a high tolerance to Monilinia spp. while maintaining fruit quality. In this study, the tolerance to Monilinia laxa and agronomic and biochemical characteristics of forty-two hybrids derived from the ‘Andross’ × ‘Calante’ cross were studied under controlled conditions during two consecutive years, and compared with their parents. The assessment of tolerance to brown rot was estimated on inoculated fruit with M. laxa, recording the incidence of brown rot and colonization, lesion diameter and extent of colonization, to establish the severity of incidence and colonization. At harvest, physicochemical traits and antioxidant compounds (vitamin C, total phenolics, flavonoids and relative antioxidant capacity) were determined. We have found inverse relationships between fruit firmness, pH, titratable acidity and antioxidant contents with the disease symptoms in fruit. Our results confirm that the accumulation of antioxidants tends to reduce the lesion and colonization in inoculated fruit. Principal component analysis allowed the selection of two genotypes, AC-24 and AC-93, of ‘Calanda’-type peaches with a known standard quality, high antioxidant content and minimal susceptibility to brown rot.

Improving peach cultivars with superior traits is a primary objective of breeding initiatives. In this study, we aimed to elucidate the genetic basis of key agronomic and fruit-related traits using a reproducible ddRAD-seq protocol applied to a discovery panel of 90 peach accessions. Our customized workflow (available at https://github.com/najlaksouri/GWAS-Workflow) integrates three variant callers and tests up to seven models to perform a robust genome-wide association analysis (GWAS). This approach produced 13,045 high-confidence SNPs and identified Blink as the most suitable model, effectively balancing false positive and negative associations. A total of 16 significant associations signals were unveiled for six highly heritable traits (H2 > 0.5), including harvest date, fruit weight, flesh firmness, contents of flavonoids, anthocyanins and sorbitol. By assessing the allelic effect of significant markers on phenotypic attributes, nine SNP alleles were deemed favorable. Notably, a promising marker (SNC_034014.1_7012470) demonstrated simultaneous association with harvest date and fruit firmness, displaying a positive allelic effect on both traits. We anticipate that this marker can serve as a good predictor of firmer varieties. Candidate causal genes were shortlisted when fulfilling the following criteria: (i) position within the linkage disequilibrium block, (ii) functional annotation and (iii) expression pattern. A comprehensive bibliographic review of previously reported QTLs mapping nearby the associated markers allowed us to benchmark the accuracy of our approach. Despite the moderate germplasm size, ddRAD-seq allowed us to produce an accurate representation of the peach genome, resulting in SNP markers suitable for empirical association studies. Together with candidate genes, they lay the foundation for further genetic dissection of peach key traits., This work was funded by Spanish Research Agency [grants AGL2014-52063-R, AGL2017-83358-R, PID2023-146749OB-I00 MCIN/AEI/https://doi.org/10.13039/501100011033 and by “ERDF A way of making Europe”] and the Government of Aragón [grantsA09_20R, A09_23R, A10_20R], which were co-financed with FEDER funds and the CSIC [grant2020AEP119]. N.K. was funded with a pre-doctoral contract awarded by the Government of Aragón (2018–2023) and C.F-i-F. by a JAE-Pre fellowship from CSIC (2008–2013)

The ornithine–urea cycle (urea cycle) makes a signifcant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea
cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants.
High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine
decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity
of copper amine oxidase, which releases ammonium from putrescine, was signifcantly decreased in both shoots
and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro
assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early
supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cyclerelated proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important
protective mechanisms limiting ammonium toxicity in M. truncatula. These fndings demonstrate the relevance of the
urea cycle to polyamine metabolism in higher plants., This work was supported by the grants from the Spanish Government
AGL2014-52396-P (MICINN) and AGL2017-86293-P (MINECO/
FEDER) to JFM, and the Basque Government, Spain, IT-1018-16
(UPV/EHU-GV) to RE. MU is a recipient of a pre-doctoral fellowship from the Government of Navarre, Spain. JB and PLG have received pre-doctoral fellowships from the Public University of Navarre,
Spain. PT has received funding from the Italian Ministry of Education,
University and Research (Grant to Department of Science, University
‘Roma Tre’-‘Dipartimenti di Eccellenza’, ARTICOLO 1, COMMI 314–
337. LEGGE 423 232/2016; PRIN 2017—CUP F84I19000730005).
Partial support was obtained from the Spanish State Research Agency
AGL2017-83358-R (AEI/FEDER) and the Government of Aragon,
Spain, Group A09-20R to YG. Open Access funding was provided by the
Public University of Navarra.