Mango is an extremely perishable fruit with a short postharvest time, and a considerable proportion of harvested mangoes become spoiled due to the postharvest decay in mango-producing areas of the world. The current study was designed to evaluate the effects of chitosan on the storage life of mango. Mango samples were coated with 750, 1000, and 1500 ppm chitosan solution, before storing them in the open or zip-bags under ambient and refrigeration conditions for different storage periods. Changes in different physical and chemical parameters were recorded to evaluate the treatments’ effectiveness in extending fruit shelf-life and sustaining postharvest quality of mangoes. The results showed that chitosan coating was able to reduce weight loss up to 65% in comparison to the uncoated control. Total mold and bacterial counts were also significantly lower in postharvest mangos when they were coated with chitosan compared to the uncoated samples. In addition, different fruit quality attributes, such as vitamin C content, titratable acidity, sugar content, ash, and protein content were also retained to a considerable extent by the chitosan coatings. Chitosan at refrigeration temperature (4 °C) with zip-bag packaging had a greater positive effect on fruit shelf-life, weight maintenance, and quality attributes than ambient temperature. Among the different coating concentrations, 1000 ppm chitosan solutions could provide better performance to extend the shelf-life of mango fruit while maintaining quality attributes. Altogether, our findings suggest that chitosan coating effectively prolongs the storage life of mango fruit and maintains fruit quality during storage, and offers promising potential for successful commercialization of this edible coating for mango growers and the industry.

Flavonoids are secondary metabolites associated with plant seed coat and flower color. These compounds provide health benefits to humans as anti-inflammatory and antioxidant compounds. The expression of the late biosynthetic genes in the flavonoid pathway is controlled by a ternary MBW protein complex consisting of interfacing MYB, beta-helix–loop–helix (bHLH), and WD40 Repeat (WDR) proteins. P, the master regulator gene of the flavonoid expression in common bean (Phaseolus vulgaris L.), was recently determined to encode a bHLH protein. The T and Z genes control the distribution of color in bean seeds and flowers and have historically been considered regulators of the flavonoid gene expression. T and Z candidates were identified using reverse genetics based on genetic mapping, phylogenetic analysis, and mutant analysis. Domain and AlphaFold2 structure analyses determined that T encodes a seven-bladed β-propeller WDR protein, while Z encodes a R2R3 MYB protein. Deletions and SNPs in T and Z mutants, respectively, altered the 3D structure of these proteins. Modeling of the Z MYB/P bHLH/T WDR MBW complex identified interfacing sequence domains and motifs in all three genes that are conserved in dicots. One Z MYB motif is a possible beta-molecular recognition feature (β-MoRF) that only appears in a structured state when Z MYB is modeled as a component of a MBW complex. Complexes containing mutant T and Z proteins changed the interaction of members of the complex in ways that would alter their role in regulating the expression of genes in the flavonoid pathway.

White mold (WM) is a major disease in common bean (Phaseolus vulgaris L.), and its complex quantitative genetic control limits the development of WM resistant cultivars. WM2.2, one of the nine meta-QTL with a major effect on WM tolerance, explains up to 35% of the phenotypic variation and was previously mapped to a large genomic interval on Pv02. Our objective was to narrow the interval of this QTL using combined approach of classic QTL mapping and QTL-based bulk segregant analysis (BSA), and confirming those results with Khufu de novo QTL-seq. The phenotypic and genotypic data from two RIL populations, ‘Raven’/I9365-31 (R31) and ‘AN–37’/PS02–029C–20 (Z0726-9), were used to select resistant and susceptible lines to generate subpopulations for bulk DNA sequencing. The QTL physical interval was determined by considering overlapping interval of the identified QTL or peak region in both populations by three independent QTL mapping analyses. Our findings revealed that meta-QTL WM2.2 consists of three regions, WM2.2a (4.27-5.76 Mb; euchromatic), WM 2.2b (12.19 to 17.61 Mb; heterochromatic), and WM2.2c (23.01-25.74 Mb; heterochromatic) found in both populations. Gene models encoding for gibberellin 2-oxidase 8, pentatricopeptide repeat, and heat-shock proteins are the likely candidate genes associated with WM2.2a resistance. A TIR-NBS-LRR class of disease resistance protein (Phvul.002G09200) and LRR domain containing family proteins are potential candidate genes associated with WM2.2b resistance. Nine gene models encoding disease resistance protein [pathogenesis-related thaumatin superfamily protein and disease resistance-responsive (dirigent-like protein) family protein etc] found within the WM2.2c QTL interval are putative candidate genes. WM2.2a region is most likely associated with avoidance mechanisms while WM2.2b and WM2.2c regions trigger physiological resistance based on putative candidate genes.

White mold (WM), caused by the ubiquitous fungus Sclerotinia sclerotiorum , is a devastating disease that limits production and quality of dry bean globally. In the present study, classic linkage mapping combined with QTL‐seq were employed in two recombinant inbred line (RIL) populations, “Montrose”/I9365‐25 (M25) and “Raven”/I9365‐31 (R31), with the initial goal of fine‐mapping QTL WM5.4 and WM7.5 that condition WM resistance. The RILs were phenotyped for WM reactions under greenhouse (straw test) and field environments. The general region of WM5.4 and WM7.5 were reconfirmed with both mapping strategies within each population. Combining the results from both mapping strategies, WM5.4 was delimited to a 22.60–36.25 Mb interval in the heterochromatic regions on Pv05, while WM7.5 was narrowed to a 0.83 Mb (3.99–4.82 Mb) region on the Pv07 chromosome. Furthermore, additional QTL WM2.2a (3.81–7.24 Mb), WM2.2b (11.18–17.37 Mb, heterochromatic region), and WM2.2c (23.33–25.94 Mb) were mapped to a narrowed genomic interval on Pv02 and WM4.2 in a 0.89 Mb physical interval at the distal end of Pv04 chromosome. Gene models encoding gibberellin 2‐oxidase proteins regulating plant architecture are likely candidate genes associated with WM2.2a resistance. Nine gene models encoding a disease resistance protein (quinone reductase family protein and ATWRKY69) found within the WM5.4 QTL interval are putative candidate genes. Clusters of 13 and 5 copies of gene models encoding cysteine‐rich receptor‐like kinase and receptor‐like protein kinase‐related family proteins, respectively, are potential candidate genes associated with WM7.5 resistance and most likely trigger physiological resistance to WM. Acquired knowledge of the narrowed major QTL intervals, flanking markers, and candidate genes provides promising opportunities to develop functional molecular markers to implement marker‐assisted selection for WM resistant dry bean cultivars.

Common bean (Phaseolus vulgaris L.) market classes have distinct seed coat colors, which are directly related to the diverse flavonoids found in the mature seed coat. To understand and elucidate the molecular mechanisms underlying the regulation of seed coat color, RNA-Seq data was collected from the black bean 5-593 and used for a differential gene expression and enrichment analysis from four different seed coat color development stages. 5-593 carries dominant alleles for 10 of the 11 major genes that control seed coat color and expression and has historically been used to develop introgression lines used for seed coat genetic analysis. Pairwise comparison among the four stages identified 6,294 differentially expressed genes (DEGs) varying from 508 to 5,780 DEGs depending on the compared stages. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that phenylpropanoid biosynthesis, flavonoid biosynthesis, and plant hormone signal transduction comprised the principal pathways expressed during bean seed coat pigment development. Transcriptome analysis suggested that most structural genes for flavonoid biosynthesis and some potential regulatory genes were significantly differentially expressed. Further studies detected 29 DEGs as important candidate genes governing the key enzymatic flavonoid biosynthetic pathways for common bean seed coat color development. Additionally, four gene models, Pv5-593.02G016100, 593.02G078700, Pv5-593.02G090900, and Pv5-593.06G121300, encode MYB-like transcription factor family protein were identified as strong candidate regulatory genes in anthocyanin biosynthesis which could regulate the expression levels of some important structural genes in flavonoid biosynthesis pathway. These findings provide a framework to draw new insights into the molecular networks underlying common bean seed coat pigment development.

Domestication imposed radical selection pressures on plants, transforming them into crops that support global populations today. Here, we investigate the loss of seed dispersal via pod shattering during common bean (Phaseolus vulgaris L.) domestication. We identified PvMYB26 mutations in all three main gene pools of common bean, including an 8 kb deletion in Middle American lines eliminating the gene's transcription start site and promoter; a frameshift/truncation deletion in the independently domesticated Andean population; and another frameshift/truncation insertion in the genetic background of the "undomesticated" debouckii population. Mutants with the 8 kb deletion express PvMYB26 at <1% of the level of wild types and produce 44% less pod lignin. RNA in situ hybridization and fluorescence microscopy show that PvMYB26 is expressed in the lignified fiber layer of pods, while mutants show no visible expression and have a greatly reduced fiber layer. Sequencing of 327 accessions revealed that the mutation is nearly diagnostic for domestication status among Middle American common bean and identified a 125 kb hard selective sweep, indicating the gene's importance in domestication. The main Andean frameshift mutation is found in 84.5% of Andean domesticates but 0% of wild lines, while the debouckii truncation was identified in six domesticated lines of Race Peru, suggesting a third proto-domestication of common bean may have occurred in Ecuador and/or northern Peru. Wild haplotypes most like Middle American domesticates are found in eastern Jalisco, Mexico, strongly suggesting West-Central Mexico as the site of common bean domestication and the rise of agriculture in Middle America.