A Novel Introgression Line Library Derived from a Wild Melon Gives Insights into the Genetics of Melon Domestication, Uncovering New Genetic Variability Useful for Breeding.

A collection of 30 melon introgression lines (ILs) was developed from the wild accession Ames 24297 (TRI) into 'Piel de Sapo' (PS) genetic background. Each IL carried an average of 1.4 introgressions from TRI, and the introgressions represented 91.4% of the TRI genome. Twenty-two ILs, representing 75% of the TRI genome, were evaluated in greenhouse (Algarrobo and Meliana) and field (Alcàsser) trials, mainly to study traits related to domestication syndrome such as fruit weight (FW) and flesh content (FFP), as well as other fruit quality traits as fruit shape (FS), flesh firmness (FF), soluble solid concentration (SSC), rind color and abscission layer. The IL collection showed an impressive variation in size-related traits, with FW ranging from 800 to 4100 g, reflecting the strong effect of the wild genome on these traits. Most of the ILs produced smaller fruits compared with PS; however, unexpectedly, the IL TRI05-2 produced bigger fruits, likely due to new epistatic interacions with the PS genetic background. In contrast, the genotypic effect for FS was smaller, and few QTLs with notable effects were detected. Interestingly, variability was also observed for FFP, FF and SSC, rind color and abscission layer formation. Genes in these introgressions are candidates for having been involved in melon domestication and diversification as well. These results confirm that the TRI IL collection is a very powerful tool for mapping traits of agronomic interest in melon, allowing the confirmation of previously reported QTLs and the identification of new ones to better understand the domestication process of this crop.

Effects of a Raisin Supplement on Cognitive Performance, Quality of Life, and Functional Activities in Healthy Older Adults-Randomized Clinical Trial.

The objective of this study was to evaluate the effects of consuming 50 g of raisins on cognitive performance, quality of life, and functional activities in healthy older adults. This is a parallel randomized controlled clinical trial, in which 80 subjects over 70 years of age participated. For 6 months, the intervention group (IG; n = 40) consumed 50 g of raisins per day added to their usual diet, whereas the control group (CG; n = 40) received no supplement. All variables were measured at baseline and at 6 months. Cognitive performance assessed with the Montreal Cognitive Assessment (MOCA) test shows a difference of 3.27 points (95% CI 1.59 to 4.96), p ≤ 0.001, favorable to the IG, after the intervention. Among the cognitive performances, an improvement is observed in the IG in orientation, assessed both with the MOCA test 0.49 (95% CI 0.10 to 0.87), p = 0.014, and with the Mini-Mental State Examination (MMSE) test, 0.36 (95% CI 0.02 to 0.70), p = 0.038. In visuospatial/executive capacity and in language, improvements were also observed in the IG, 1.36 (95% CI 0.77 to 1.95), p = 0.001, and 0.54 points (95% CI 0.12 to 0.96), p = 0.014, respectively. Immediate and delayed recall, assessed with the Rey Auditory Verbal Learning Test, improved in the IG. In addition, the IG showed a better quality of life and greater autonomy in instrumental activities of daily living after 6 months. No significant changes were observed in the rest of the variables analyzed. Therefore, the consumption of 50 g of raisins produces a slight improvement in cognitive performance, quality of life, and functional activities in the elderly.

Effect of Polyphenolic Complements on Cognitive Function in the Elderly: A Systematic Review.

Polyphenols have been shown to be effective against many chronic diseases. These compounds could have a beneficial effect at the cognitive level. The exact mechanism by which they provide positive effects at the cognitive level is not well known, but it is believed that they could counteract neuroinflammation. The objective of this study is to review nutritional interventions that include foods or supplements rich in flavanols, flavonols, or stilbenes to the usual diet on cognitive deterioration in people over 50 years of age. Clinical trials published in PubMed and Web of Science from 1 March 2010 to 1 March 2020 were explored, from which 14 studies were selected. All of them showed some improvement after the intervention. In interventions with flavanols and stilbenes, relevant improvements have been observed both in healthy patients and in patients with established cognitive impairment. Most studies agree that the greatest benefits are found with high doses and longer duration treatments. The changes were fundamentally assessed through cognitive tests, and in some of the studies, through magnetic resonance imaging (fMRI). The type of cognitive test used to assess the effect of the intervention was revealed to be critical. Several studies have also shown improvements in analytical parameters and blood pressure.

Genetic Control of Reproductive Traits under Different Temperature Regimes in Inbred Line Populations Derived from Crosses between S. pimpinellifolium and S. lycopersicum Accessions.

In the present work, we study the genetic control of reproductive traits under different heat stress conditions in two populations of inbred lines derived from crosses between two S. pimpinellifolium accessions and two tomato cultivars (E9×L5 and E6203×LA1589). The temperature increase affected the reproductive traits, especially at extremely high temperatures, where only a few lines were able to set fruits. Even though a relative modest number of QTLs was identified, two clusters of QTLs involved in the responses of reproductive traits to heat stress were detected in both populations on chromosomes 1 and 2. Interestingly, several epistatic interactions were detected in the E9×L5 population, which were classified into three classes based on the allelic interaction: dominant (one locus suppressed the allelic effects of a second locus), co-adaptive (the double-homozygous alleles from the same parent alleles showed a higher phenotypic value than the combination of homozygous alleles from alternative parents) and transgressive (the combination of double-homozygous alleles from different parents showed better performance than double-homozygous alleles from the same parents). These results reinforce the important role of non-additive genetic variance in the response to heat stress and the potential of the new allelic combinations that arise after wide crosses.

A cryptic variation in a member of the Ovate Family Proteins is underlying the melon fruit shape QTL fsqs8.1.

KEY MESSAGE: The gene underlying the melon fruit shape QTL fsqs8.1 is a member of the Ovate Family Proteins. Variation in fruit morphology is caused by changes in gene expression likely due to a cryptic structural variation in this locus. Melon cultivars have a wide range of fruit morphologies. Quantitative trait loci (QTL) have been identified underlying such diversity. This research focuses on the fruit shape QTL fsqs8.1, previously detected in a cross between the accession PI 124112 (CALC, producing elongated fruit) and the cultivar 'Piel de Sapo' (PS, producing oval fruit). The CALC fsqs8.1 allele induced round fruit shape, being responsible for the transgressive segregation for this trait observed in that population. In fact, the introgression line CALC8-1, carrying the fsqs8.1 locus from CALC into the PS genetic background, produced perfect round fruit. Following a map-based cloning approach, we found that the gene underlying fsqs8.1 is a member of the Ovate Family Proteins (OFP), CmOFP13, likely a homologue of AtOFP1 and SlOFP20 from Arabidopsis thaliana and tomato, respectively. The induction of the round shape was due to the higher expression of the CALC allele at the early ovary development stage. The fsqs8.1 locus showed an important structural variation, being CmOFP13 surrounded by two deletions in the CALC genome. The deletions are present at very low frequency in melon germplasm. Deletions and single nucleotide polymorphisms in the fsqs8.1 locus could not be not associated with variation in fruit shape among different melon accessions, what indicates that other genetic factors should be involved to induce the CALC fsqs8.1 allele effects. Therefore, fsqs8.1 is an example of a cryptic variation that alters gene expression, likely due to structural variation, resulting in phenotypic changes in melon fruit morphology.

Identification of tomato accessions as source of new genes for improving heat tolerance: from controlled experiments to field.

BACKGROUND: Due to global warming, the search for new sources for heat tolerance and the identification of genes involved in this process has become an important challenge as of today. The main objective of the current research was to verify whether the heat tolerance determined in controlled greenhouse experiments could be a good predictor of the agronomic performance in field cultivation under climatic high temperature stress. RESULTS: Tomato accessions were grown in greenhouse under three temperature regimes: control (T1), moderate (T2) and extreme heat stress (T3). Reproductive traits (flower and fruit number and fruit set) were used to define heat tolerance. In a first screening, heat tolerance was evaluated in 219 tomato accessions. A total of 51 accessions were identified as being potentially heat tolerant. Among those, 28 accessions, together with 10 accessions from Italy (7) and Bulgaria (3), selected for their heat tolerance in the field in parallel experiments, were re-evaluated at three temperature treatments. Sixteen tomato accessions showed a significant heat tolerance at T3, including five wild species, two traditional cultivars and four commercial varieties, one accession from Bulgaria and four from Italy. The 15 most promising accessions for heat tolerance were assayed in field trials in Italy and Bulgaria, confirming the good performance of most of them at high temperatures. Finally, a differential gene expression analysis in pre-anthesis (ovary) and post-anthesis (developing fruit) under heat stress among pairs of contrasting genotypes (tolerant and sensitive from traditional and modern groups) showed that the major differential responses were produced in post-anthesis fruit. The response of the sensitive genotypes included the induction of HSP genes, whereas the tolerant genotype response included the induction of genes involved in the regulation of hormones or enzymes such as abscisic acid and transferases. CONCLUSIONS: The high temperature tolerance of fifteen tomato accessions observed in controlled greenhouse experiments were confirmed in agronomic field experiments providing new sources of heat tolerance that could be incorporated into breeding programs. A DEG analysis showed the complex response of tomato to heat and deciphered the different mechanisms activated in sensitive and tolerant tomato accessions under heat stress.

Genetic Control of Reproductive Traits in Tomatoes Under High Temperature.

Global climate change is increasing the range of temperatures that crop plants must face during their life cycle, giving negative effects to yields. In this changing scenario, understanding the genetic control of plant responses to a range of increasing temperature conditions is a prerequisite to developing cultivars with increased resilience. The current work reports the identification of Quantitative Trait Loci (QTL) involved in reproductive traits affected by temperature, such as the flower number (FLN) and fruit number (FRN) per truss and percentage of fruit set (FRS), stigma exsertion (SE), pollen viability (PV) and the incidence of the physiological disorder tipburn (TB). These traits were investigated in 168 Recombinant Inbred Lines (RIL) and 52 Introgression Lines (IL) derived from the cross between Solanum lycopersicum var. "MoneyMaker" and S. pimpinellifolium accession TO-937. Mapping populations were cultivated under increased temperature regimen conditions: T1 (25°C day/21°C night), T2 (30°C day/25°C night) and T3 (35°C day/30°C night). The increase in temperature drastically affected several reproductive traits, for example, FRS in Moneymaker was reduced between 75 and 87% at T2 and T3 when compared to T1, while several RILs showed a reduction of less than 50%. QTL analysis allowed the identification of genomic regions affecting these traits at different temperatures regimens. A total of 22 QTLs involved in reproductive traits at different temperatures were identified by multi-environmental QTL analysis and eight involved in pollen viability traits. Most QTLs were temperature specific, except QTLs on chromosomes 1, 2, 4, 6, and 12. Moreover, a QTL located in chromosome 7 was identified for low incidence of TP in the RIL population, which was confirmed in ILs with introgressions on chromosome 7. Furthermore, ILs with introgressions in chromosomes 1 and 12 had good FRN and FRS in T3 in replicated trials. These results represent a catalog of QTLs and pre-breeding materials that could be used as the starting point for deciphering the genetic control of the genetic response of reproductive traits at different temperatures and paving the road for developing new cultivars adapted to climate change.

Re-evaluation of the role of Indian germplasm as center of melon diversification based on genotyping-by-sequencing analysis.

BACKGROUND: The importance of Indian germplasm as origin and primary center of diversity of cultivated melon is widely accepted. Genetic diversity of several collections from Indian has been studied previously, although an integrated analysis of these collections in a global diversity perspective has not been possible. In this study, a sample of Indian collections together with a selection of world-wide cultivars to analyze the genetic diversity structure based on Genotype by Sequence data. RESULTS: A set of 6158 informative Single Nucleotide Polymorphism (SNP) in 175 melon accessions was generated. Melon germplasm could be classified into six major groups, in concordance with horticultural groups. Indian group was in the center of the diversity plot, with the highest genetic diversity. No strict genetic differentiation between wild and cultivated accessions was appreciated in this group. Genomic regions likely involved in the process of diversification were also found. Interestingly, some SNPs differentiating inodorus and cantalupensis groups are linked to Quantitiative Trait Loci involved in ripening behavior (a major characteristic that differentiate those groups). Linkage disequilibrium was found to be low (17 kb), with more rapid decay in euchromatic (8 kb) than heterochromatic (30 kb) regions, demonstrating that recombination events do occur within heterochromatn, although at lower frequency than in euchromatin. Concomitantly, haplotype blocks were relatively small (59 kb). Some of those haplotype blocks were found fixed in different melon groups, being therefore candidate regions that are involved in the diversification of melon cultivars. CONCLUSIONS: The results support the hypothesis that India is the primary center of diversity of melon, Occidental and Far-East cultivars have been developed by divergent selection. Indian germplasm is genetically distinct from African germplasm, supporting independent domestication events. The current set of traditional Indian accessions may be considered as a population rather than a standard collection of fixed landraces with high intercrossing between cultivated and wild melons.

Effect of silicon addition on soybean (Glycine max) and cucumber (Cucumis sativus) plants grown under iron deficiency.

Silicon is considered an essential element in several crops enhancing growth and alleviating different biotic and abiotic stresses. In this work, the role of Si in the alleviation of iron deficiency symptoms and in the Fe distribution in iron deficient plants has been studied. Thus, soybean and cucumber plants grown in hydroponic culture under iron limiting conditions were treated with different Si doses (0.0, 0.5 and 1.0 mM). The use of a strong chelating agent such as HBED avoided Fe co-precipitation in the nutrient solution and allowed for the first time the analysis of Si effect in iron nutrition without the interference of the iron rhizospheric precipitation. SPAD index, plant growth parameters and mineral content in plant organs were determined. For soybean, the addition of 0.5 mM of Si to the nutrient solution without iron, initially or continuously during the experiment, prevented the chlorophyll degradation, slowed down the growth decrease due to the iron deficiency and maintained the Fe content in leaves. In cucumber, Si addition delayed the decrease of stem dry weight, stem length, node number and iron content in stems and roots independently of the dose, but no-effect was observed in chlorosis symptoms alleviation in leaves. The observed response to Si addition in iron deficiency was plant-specific, probably related with the different Fe efficiency strategies developed by these two species.

Physiological responses and differential gene expression in Prunus rootstocks under iron deficiency conditions.

Two Prunus rootstocks, the Myrobalan plum P 2175 and the interspecific peach-almond hybrid, Felinem, were studied to characterize their biochemical and molecular responses induced under iron-Deficient conditions. Plants of both genotypes were submitted to different treatments using a hydroponic system that permitted removal of Fe from the nutrient solution. Control plants were grown in 90 µM Fe (III)-EDTA, Deficient plants were grown in an iron free solution, and plants submitted to an Inductor treatment were resupplied with 180 µM Fe (III)-EDTA over 1 and 2 days after a period of 4 or 15 days of growth on an iron-free solution. Felinem increased the activity of the iron chelate reductase (FC-R) in the Inductor treatment after 4 days of iron deprivation. In contrast, P 2175 did not show any response after at least 15 days without iron. The induction of the FC-R activity in this genotype was coincident in time with the medium acidification. These results suggest two different mechanisms of iron chlorosis tolerance in both Strategy I genotypes. Felinem would use the iron reduction as the main mechanism to capture the iron from the soil, and in P 2175, the mechanism of response would be slower and start with the acidification of the medium synchronized with the gradual loss of chlorophyll in leaves. To better understand the control of these responses at the molecular level, the differential expression of PFRO2, PIRT1 and PAHA2 genes involved in the reductase activity, the iron transport in roots, and the proton release, respectively, were analyzed. The expression of these genes, estimated by quantitative real-time PCR, was different between genotypes and among treatments. The results were in agreement with the physiological responses observed.

A comparative analysis into the genetic bases of morphology in tomato varieties exhibiting elongated fruit shape.

Fruit shape is a quantitatively inherited character. In tomato, two major loci, sun and ovate, control fruit shape index, which is the ratio of fruit height over width. In this study, we measured many additional fruit shape features in three inter-specific F2 populations using the software application Tomato Analyzer. These populations were derived from varieties carrying elongated fruit but for which the major shape loci differed. We compared the effect of the major fruit shape loci with overall shape, as well as with the distal and proximal end shape features in each population. sun and ovate represented the largest effect on fruit shape in the Howard German and Sausage F2 populations, respectively. The largest effect QTL in the Rio Grande population carrying neither sun nor ovate, were fs8.1 on chromosome 8 and tri2.1/dblk2.1 on chromosome 2. These latter loci were also segregating in the other two populations, thus indicating common regions that control shape across the three populations. The phenotypic analyses showed that sun and ovate contributed to almost all aspects of shape such as the distal and proximal end features. In Rio Grande however, the largest effect QTL did not control all aspects of shape and the distal and proximal features were distinctly controlled in that population. Combined, our results implied that within the cultivated tomato germplasm pool the largest effect on elongated fruit shape was controlled by a combination of the loci sun, ovate, fs8.1 and tri2.1/dblk2.1.