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Blackberry plants were sprayed with methyl jasmonate (MJ 0, 1, 2 or 3 mmol L−1), 2 weeks before tentative harvest maturity, to evaluate its influence on red drupelet reversion (RDR), antioxidant capacity and postharvest quality during cold storage up to 12 days. MJ significantly reduced RDR and weight loss while maintaining higher anthocyanins and flavonoids during cold storage for 12 days. MJ application upregulated phenolic metabolism by maintaining higher phenylalanine ammonia lyase activity, and showed higher total antioxidants, ascorbic acid, and glutathione content. MJ-treated blackberries displayed higher activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase enzymes, than control for 12 days of cold storage. Moreover, MJ-treated fruit suppressed the production of hydrogen peroxide radicals and malondialdehyde with lower activities of polyphenol oxidase and lipoxygenase enzymes. In conclusion, preharvest application of MJ has the potential to reduce RDR, improve antioxidant capacity and maintain fruit quality of cold stored blackberries. [ABSTRACT FROM AUTHOR]

Introduction: Horticultural plant breeding programs often demand large volumes of phenotypic data to capture visual variation in quality of harvested products. Increasing the throughput potential of phenomic pipelines enables breeders to consider data-hungry molecular breeding strategies such as genome-wide association studies and genomic selection. Methods: We present an R-based web application called ShinyFruit for imagebased phenotyping of size, shape, and color-related qualities in fruits and vegetables. Here, we have demonstrated one potential application for ShinyFruit by comparing its estimates of fruit length, width, and red drupelet reversion (RDR) with ImageJ and analogous manual phenotyping techniques in a population of blackberry cultivars and breeding selections from the University of Arkansas System Division of Agriculture Fruit Breeding Program. Results: ShinyFruit results shared a strong positive correlation with manual measurements for blackberry length (r = 0.96) and ImageJ estimates of RDR (r = 0.96) and significant, albeit weaker, correlations with manual RDR estimation methods (r = 0.62 - 0.70). Neither phenotyping method detected genotypic differences in blackberry fruit width, suggesting that this trait is unlikely to be heritable in the population observed. Discussion: It is likely that implementing a treatment to promote RDR expression in future studies might strengthen the documented correlation between phenotyping methods by maximizing genotypic variance. Even so, our analysis has suggested that ShinyFruit provides a viable, open-source solution to efficient phenotyping of size and color in blackberry fruit. The ability for users to adjust analysis settings should also extend its utility to a wide range of fruits and vegetables. [ABSTRACT FROM AUTHOR]

IntroductionHorticultural plant breeding programs often demand large volumes of phenotypic data to capture visual variation in quality of harvested products. Increasing the throughput potential of phenomic pipelines enables breeders to consider data-hungry molecular breeding strategies such as genome-wide association studies and genomic selection.MethodsWe present an R-based web application called ShinyFruit for image-based phenotyping of size, shape, and color-related qualities in fruits and vegetables. Here, we have demonstrated one potential application for ShinyFruit by comparing its estimates of fruit length, width, and red drupelet reversion (RDR) with ImageJ and analogous manual phenotyping techniques in a population of blackberry cultivars and breeding selections from the University of Arkansas System Division of Agriculture Fruit Breeding Program.ResultsShinyFruit results shared a strong positive correlation with manual measurements for blackberry length (r = 0.96) and ImageJ estimates of RDR (r = 0.96) and significant, albeit weaker, correlations with manual RDR estimation methods (r = 0.62 - 0.70). Neither phenotyping method detected genotypic differences in blackberry fruit width, suggesting that this trait is unlikely to be heritable in the population observed.DiscussionIt is likely that implementing a treatment to promote RDR expression in future studies might strengthen the documented correlation between phenotyping methods by maximizing genotypic variance. Even so, our analysis has suggested that ShinyFruit provides a viable, open-source solution to efficient phenotyping of size and color in blackberry fruit. The ability for users to adjust analysis settings should also extend its utility to a wide range of fruits and vegetables.

Introduction: Blackberry (Rubus subgenus Rubus) is a soft-fruited specialty crop that often suffers economic losses due to degradation in the shipping process. During transportation, fresh-market blackberries commonly leak, decay, deform, or become discolored through a disorder known as red drupelet reversion (RDR). Over the past 50 years, breeding programs have achieved better fruit firmness and postharvest quality through traditional selection methods, but the underlying genetic variation is poorly understood. Methods: We conducted a genome-wide association of fruit firmness and RDR measured in 300 tetraploid fresh-market blackberry genotypes from 2019-2021 with 65,995 SNPs concentrated in genic regions of the R. argutus reference genome. Results: Fruit firmness and RDR had entry-mean broad sense heritabilities of 68% and 34%, respectively. Three variants on homologs of polygalacturonase (PG), pectin methylesterase (PME), and glucan endo-1,3-b-glucosidase explained 27% of variance in fruit firmness and were located on chromosomes Ra06, Ra01, and Ra02, respectively. Another PG homolog variant on chromosome Ra02 explained 8% of variance in RDR, but it was in strong linkage disequilibrium with 212 other RDR-associated SNPs across a 23 Mb region. A large cluster of six PME and PME inhibitor homologs was located near the fruit firmness quantitative trait locus (QTL) identified on Ra01. RDR and fruit firmness shared a significant negative correlation (r = -0.28) and overlapping QTL regions on Ra02 in this study. Discussion: Our work demonstrates the complex nature of postharvest quality traits in blackberry, which are likely controlled by many small-effect QTLs. This study is the first large-scale effort to map the genetic control of quantitative traits in blackberry and provides a strong framework for future GWAS. Phenotypic and genotypic datasets may be used to train genomic selection models that target the improvement of postharvest quality. [ABSTRACT FROM AUTHOR]

IntroductionBlackberry (Rubus subgenus Rubus) is a soft-fruited specialty crop that often suffers economic losses due to degradation in the shipping process. During transportation, fresh-market blackberries commonly leak, decay, deform, or become discolored through a disorder known as red drupelet reversion (RDR). Over the past 50 years, breeding programs have achieved better fruit firmness and postharvest quality through traditional selection methods, but the underlying genetic variation is poorly understood.MethodsWe conducted a genome-wide association of fruit firmness and RDR measured in 300 tetraploid fresh-market blackberry genotypes from 2019-2021 with 65,995 SNPs concentrated in genic regions of the R. argutus reference genome.ResultsFruit firmness and RDR had entry-mean broad sense heritabilities of 68% and 34%, respectively. Three variants on homologs of polygalacturonase (PG), pectin methylesterase (PME), and glucan endo-1,3-β-glucosidase explained 27% of variance in fruit firmness and were located on chromosomes Ra06, Ra01, and Ra02, respectively. Another PG homolog variant on chromosome Ra02 explained 8% of variance in RDR, but it was in strong linkage disequilibrium with 212 other RDR-associated SNPs across a 23 Mb region. A large cluster of six PME and PME inhibitor homologs was located near the fruit firmness quantitative trait locus (QTL) identified on Ra01. RDR and fruit firmness shared a significant negative correlation (r = -0.28) and overlapping QTL regions on Ra02 in this study.DiscussionOur work demonstrates the complex nature of postharvest quality traits in blackberry, which are likely controlled by many small-effect QTLs. This study is the first large-scale effort to map the genetic control of quantitative traits in blackberry and provides a strong framework for future GWAS. Phenotypic and genotypic datasets may be used to train genomic selection models that target the improvement of postharvest quality.

Blackberry (Rubus spp.) is susceptible to red drupelet reversion (RDR) during postharvest supply chain which has been associated with anthocyanin degradation. The efficacy of preharvest melatonin spray application (0, 50, 100 and 200 µmol L−1) two weeks before anticipated harvest on RDR, anthocyanin degradation, antioxidant capacity and postharvest quality of blackberries was investigated. Following the harvest, the blackberry fruit was stored at 2 ± 1 °C and 85–90 % relative humidity up to 12 d. Blackberries sprayed with 100 µmol L−1 melatonin mitigated RDR (40.9 %), reduced weight loss (44.8 %) and fruit decay (FD) (24.6 %) as compared to control. Melatonin spray application (100 µmol L−1) significantly delayed the degradation of total anthocyanins, glutathione (GSH), ascorbic acid (AsA) and 2, 2-diphenyl-1-picrylhydrazile (DPPH) radical scavenging in cold stored blackberries. Similarly, fruit treated with 100 µmol L−1 melatonin expressed higher activities of antioxidant enzymes including glutathione reductase (GR), catalase (CAT), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and ascorbate peroxidase (APX). Conversely, fruit treated with 50 µmol L−1 melatonin improved soluble solids content (SSC), total flavonoids, phenolics, carotenoids and activity of superoxide dismutase (SOD). In addition, melatonin spray applications considerably reduced malondialdehyde (MDA), hydrogen peroxide radicals (H 2 O 2), total chlorophyll, and activity of polyphenol oxidase (PPO) during the entire period of storage. In conclusion, melatonin spray application (100 µmol L−1) two weeks before anticipated harvest alleviated RDR in blackberry fruit by improving antioxidant potential and retaining better postharvest quality for 12 d of cold storage. • Preharvest melatonin spray alleviated RDR and maintained postharvest quality. • Melatonin spray maintained higher TAC, TPC and TFC, and activities of CAT and SOD. • Melatonin application suppressed H 2 O 2 , MDA and activity of PPO enzyme. • Melatonin sprayed application upregulated AsA-GSH cycle in blackberries. [ABSTRACT FROM AUTHOR]

• RDR is induced by fruit vibration during commercial transportation. • RDR is not associated with a reduction in anthocyanin contents. • Vibration provoke a loss of anthocyanin agglomerates, resulting in RDR appearance. Red Drupelet Reversion (RDR) in blackberry is a physiological disorder where numerous fruit drupelets regress to red from black color during post-harvest handling. The specific mechanism causing RDR is still unknown; however, numerous studies have suggested that anthocyanin contents could be involved in this phenomenon. Recently, it has been reported that RDR in cultivars 'Ouachita', 'Triple Crown' and 'Apache' could be associated with a reduction (56–63 %) in anthocyanin contents after 24 h of storage. Interestingly, other studies have observed that RDR could be linked to fruit mechanical damage during transportation; specifically, due to fruit vibration (10 Hz and acceleration of 0.5 g). Based on this notion, the main goal of the present study was to establish a fruit vibration model to evaluate the relationship between mechanical damage, anthocyanin content and RDR appearance. Blackberry clamshells cv. 'APF-122′ (170 g) were subjected to vibration (10 Hz and acceleration of 0.5 g) during 1, 3, and 5 min to induce RDR. Color and anthocyanin content were evaluated at 0, 24, 48, 72, 96 and 120 h of storage at 1 °C. RDR was observed immediately after fruit was subjected to 5 min vibration; however, no changes were observed in anthocyanin concentration. Multiphoton microscopy revealed that reverted fruit possessed anthocyanins dispersed within the cells; in contrast, no reverted fruit held anthocyanins in spherical agglomerates. Also, it was observed that anthocyanin fluorescence emission was reduced in reverted drupelet, suggesting changes in intermolecular interactions between anthocyanins. Interestingly, a reduction in anthocyanin concentration in reverted fruit was observed only after 72 h of storage; indicating that anthocyanin content may not be involved in the RDR process. Taken together, these results suggest that blackberry color reversion could be associated with changes in anthocyanin intermolecular interactions. Further studies are in progress to corroborate this hypothesis. [ABSTRACT FROM AUTHOR]