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As global temperatures have steadily increased over past decades, studying of the impacts of heat stress on morpho-physiological traits and economic yields of horticultural crops have been increasingly gained attentions by many scientists and farmers. Hot pepper (Capsicum annuum L.) is an important vegetable crop mostly grown in open-fields in South Korea. In this study, the impacts of prolonged heat stress on three hot pepper genotypes differing by levels of stress susceptibility were evaluated. The study was conducted in two different temperature-controlled greenhouses for 75 days. 48 days old plants were grown in control and heat-treated greenhouses where the temperatures had been set at 30 °C and 35 °C during the day for 75 days, respectively. Morphological, physiological, and nutrient characteristics of three accessions were measured. All hot pepper accessions were enabled to recover from prolonged heat stress exposures within approximately a month. The phenomenon of recovery was observed in some significant morphological and physiological characteristics. For example, the plant growth rate and photosynthesis rate significantly increased after 40th days of heat treatment. The heat stress sensitivity varied between genotypes. The plants that produced more fruits over biomass at early stage of heat treatment had relatively slow recovery, resulting in the largest yield loss. This key morphological characteristic can be used for future breeding program to adapt the prolonged heat stress. [ABSTRACT FROM AUTHOR]

Summary: The diverse colours of mature pepper (Capsicum spp.) fruit result from the accumulation of different carotenoids. The carotenoid biosynthetic pathway has been well elucidated in Solanaceous plants, and analysis of candidate genes involved in this process has revealed variations in carotenoid biosynthetic genes in Capsicum spp. However, the allelic variations revealed by previous studies could not fully explain the variation in fruit colour in Capsicum spp. due to technical difficulties in detecting allelic variation in multiple candidate genes in numerous samples. In this study, we uncovered allelic variations in six carotenoid biosynthetic genes, including phytoene synthase (PSY1,PSY2), lycopene β‐cyclase, β‐carotene hydroxylase, zeaxanthin epoxidase and capsanthin‐capsorubin synthase (CCS) genes, in 94 pepper accessions by single‐molecule real‐time (SMRT) sequencing. To investigate the relationship between allelic variations in the candidate genes and differences in fruit colour, we performed ultra‐performance liquid chromatography analysis using 43 accessions representing each allelic variation. Different combinations of dysfunctional mutations in PSY1 and CCS could explain variation in the compositions and levels of carotenoids in the accessions examined in this study. Our results demonstrate that SMRT sequencing technology can be used to rapidly identify allelic variation in target genes in various germplasms. The newly identified allelic variants will be useful for pepper breeding and for further analysis of carotenoid biosynthesis pathways. [ABSTRACT FROM AUTHOR]

SUMMARY: Fruit color is one of the most important traits in peppers due to its esthetic value and nutritional benefits and is determined by carotenoid composition, resulting from diverse mutations of carotenoid biosynthetic genes. The EMS204 line, derived from an EMS mutant population, presents bright‐red color, compared with the wild type Yuwolcho cultivar. HPLC analysis indicates that EMS204 fruit contains more zeaxanthin and less capsanthin and capsorubin than Yuwolcho. MutMap was used to reveal the color variation of EMS204 using an F3 population derived from a cross of EMS204 and Yuwolcho, and the locus was mapped to a 2.5‐Mbp region on chromosome 2. Among the genes in the region, a missense mutation was found in ZEP (zeaxanthin epoxidase) that results in an amino acid sequence alteration (V291 → I). A color complementation experiment with Escherichia coli and ZEP in vitro assay using thylakoid membranes revealed decreased enzymatic activity of EMS204 ZEP. Analysis of endogenous plant hormones revealed a significant reduction in abscisic acid content in EMS204. Germination assays and salinity stress experiments corroborated the lower ABA levels in the seeds. Virus‐induced gene silencing showed that ZEP silencing also results in bright‐red fruit containing less capsanthin but more zeaxanthin than control. A germplasm survey of red color accessions revealed no similar carotenoid profiles to EMS204. However, a breeding line containing a ZEP mutation showed a very similar carotenoid profile to EMS204. Our results provide a novel breeding strategy to develop red pepper cultivars containing high zeaxanthin contents using ZEP mutations. Significance Statement: Despite health benefits, such as macular protection and antioxidant effects, most crops contain low levels of zeaxanthin. Orange pepper is an important source of zeaxanthin which is scarce in our diet. We demonstrated that a leaky mutation in zeaxanthin epoxidase leads to the development of bright‐red fruit, elevated zeaxanthin levels, and affects endogenous plant hormones in pepper. Our findings suggest a novel breeding strategy for developing red pepper cultivars with high levels of zeaxanthin. [ABSTRACT FROM AUTHOR]

Climate change is an important emerging issue worldwide; the surface temperature of the earth is anticipated to increase by 0.3 °C in every decade. This elevated temperature causes an adverse impact of heat stress (HS) on vegetable crops; this has been considered as a crucial limiting factor for global food security as well as crop production. In tomato plants, HS also causes changes in physiological, morphological, biochemical, and molecular responses during all vegetative and reproductive growth stages, resulting in poor fruit quality and low yield. Thus, to select genotypes and develop tomato cultivars with heat tolerance, feasible and reliable screening strategies are required that can be adopted in breeding programs in both open-field and greenhouse conditions. In this review, we discuss previous and recent studies describing attempts to screen heat-tolerant tomato genotypes under HS that have adopted different HS regimes and threshold temperatures, and the association of heat tolerance with physiological and biochemical traits during vegetative and reproductive growth stages. In addition, we examined the wide variety of parameters to evaluate the tomato's tolerance to HS, including vegetative growth, such as leaf growth parameters, plant height and stem, as well as reproductive growth in terms of flower number, fruit set and yield, and pollen and ovule development, thereby proposing strategies for the development of heat-tolerant tomato cultivars in response to high temperature. [ABSTRACT FROM AUTHOR]

SUMMARY: Phytoene synthase (PSY1), capsanthin‐capsorubin synthase (CCS), and pseudo‐response regulator 2 (PRR2) are three major genes controlling fruit color in pepper (Capsicum spp.). However, the diversity of fruit color in pepper cannot be completely explained by these three genes. Here, we used an F2 population derived from Capsicum annuum 'SNU‐mini Orange' (SO) and C. annuum 'SNU‐mini Yellow' (SY), both harboring functional PSY1 and mutated CCS, and observed that yellow color was dominant over orange color. We performed genotyping‐by‐sequencing and mapped the genetic locus to a 6.8‐Mb region on chromosome 2, which we named CaOr. We discovered a splicing mutation in the zeaxanthin epoxidase (ZEP) gene within this region leading to a premature stop codon. HPLC analysis showed that SO contained higher amounts of zeaxanthin and total carotenoids in mature fruits than SY. A color complementation assay using Escherichia coli harboring carotenoid biosynthetic genes showed that the mutant ZEP protein had reduced enzymatic activity. Transmission electron microscopy of plastids revealed that the ZEP mutation affected plastid development with more rod‐shaped inner membrane structures in chromoplasts of mature SO fruits. To validate the role of ZEP in fruit color formation, we performed virus‐induced gene silencing of ZEP in the yellow‐fruit cultivar C. annuum 'Micropep Yellow' (MY). The silencing of ZEP caused significant changes in the ratios of zeaxanthin to its downstream products and increased total carotenoid contents. Thus, we conclude that the ZEP genotype can determine orange or yellow mature fruit color in pepper. Significance Statement: The three‐locus (Phytoene synthase, Capsanthin‐capsorubin synthase, and Pseudo response regulator2‐like) model has explained the mature fruit color in peppers, but it has recently been revealed that various genes can regulate fruit color. We demonstrated that a splicing mutation of Zeaxanthin epoxidase results in the mature color change of pepper by increasing the amount of total carotenoids. We also found that the mutation also affected the development of plastid and ABA synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-destructive strawberry fruit maturity classification and simultaneous prediction of internal quality. • Internal quality prediction technology for 'Sulhyang' strawberry fruit. • Development of predictive models based on organic analysis and hyperspectral imaging. • Two parameters identified for predicting firmness, solids, acidity, and anthocyanin. In recent years, hyperspectral imaging combined with machine learning techniques has garnered significant attention for its potential in assessing fruit maturity. This study proposes a method for predicting strawberry fruit maturity based on the harvest time. The main features of this study are as follows. 1) Selection of wavelength band associated with strawberry growth season; 2) Extraction of efficient parameters to predict strawberry maturity 3) Prediction of internal quality attributes of strawberries using extracted parameters. In this study, experts cultivated strawberries in a controlled environment and performed hyperspectral measurements and organic analyses on the fruit with minimal time delay to facilitate accurate modeling. Data augmentation techniques through cross-validation and interpolation were effective in improving model performance. The four parameters included in the model and the cumulative value of the model were available for quality prediction as additional parameters. Among these five parameter candidates, two parameters with linearity were finally identified. The predictive outcomes for firmness, soluble solids content, acidity, and anthocyanin levels in strawberry fruit, based on the two identified parameters, are as follows: The first parameter, p s , demonstrated RMSE performances of 1.0 N, 2.3 %, 0.1 %, and 2.0 mg per 100 g fresh fruit for firmness, soluble solids content, acidity, and anthocyanin, respectively. The second parameter, p 3 , showed RMSE performances of 0.6 N, 1.2 %, 0.1 %, and 1.8 mg per 100 g fresh fruit, respectively. The proposed non-destructive analysis method shows the potential to overcome the challenges associated with destructive testing methods for assessing certain internal qualities of strawberry fruit. [ABSTRACT FROM AUTHOR]

Pepper plants are subject to complex environmental factors including abiotic and biotic stresses in fields, as well as the significant effects of climate changes, including low and high temperatures. Low temperature stress in the growth and development of pepper plants is one of the most critical issues, and directly impacts the crop yield and productivity of pepper plants. Therefore, it is essential to select and breed low temperature-(LT) tolerant pepper (Capsicum annuum L.) cultivars. This research was conducted to assess the agronomical traits of 39 pepper accessions belonging to the chili and bell fruit varieties which were cultivated under two different night temperature set-points: at 15 °C for a suboptimal temperature (CT) and at 10 °C for a low temperature (LT). The plant heights (PH) of most pepper accessions in a LT were significantly decreased compared to those in a CT. The stem diameter (SD) and the length of main axis (LMA) varied depending on the genotypes under LT. Moreover, the number of flowers (NFL), total number of fruits (NFR), fruit yield (FY), fruit fresh weight (FFW), fruit length (FL), fruit diameter (FD), and number of seeds in a fruit (NSF) remarkably declined in a LT compared to in a CT. The evaluated agronomical traits between LT and CT were further applied for the correlation analysis, principal component analysis (PCA), and hierarchical cluster analysis. Notably, the FY trait was correlated with other reproductive traits including NFR, FFW, FD, and FL on the positive directions and thirty-nine LT-treated pepper accessions were clustered into seven groups by the hierarchical clustering analysis. The selected accessions were primarily involved in the positive trends with the reproductive index including NFR, FL, FD, and FFW traits and could be used for pepper breeding programs to develop LT-tolerant cultivars. [ABSTRACT FROM AUTHOR]