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The mean daily temperature effects on plant development rates and quality of compact container-grown pepper were evaluated. Compact pepper cultivars Fresh Bites Yellow and Hot Burrito were grown in greenhouses at 18 to 26 °C (Expt. 1) and 20 to 30 °C (Expt. 2) under supplemental high-pressure sodium lighting and a 16-hour photoperiod. The number of days to first open flower, to first ripe fruit, and from flower to ripe fruit were measured and the development rates calculated by taking the reciprocal (e.g., 1/day). Temperature effects were predicted by fitting a nonlinear exponential function that included the base temperature (T min) and maximum developmental rate (R max) parameters. Plant quality attributes were measured during Expt. 2. As the temperature increased, the times to flower and fruit decreased (i.e., developmental rates increased) for both cultivars. The estimated T min was 13.3 °C for ‘Fresh Bites Yellow’, and that for ‘Hot Burrito’ was 9.3 °C, whereas the R max was similar between cultivars (averages of 0.0488 at flower, 0.0190 at fruit, and 0.0252 from flower to fruit). ‘Fresh Bites Yellow’ and ‘Hot Burrito’ grown at ≈25 °C had a relatively short crop time, compact canopy, large fruit size, and high number of fruits per plant at finish. Compact peppers are new crops being grown by greenhouse floriculture operations for their ornamental and edible value, and the information from this study can help growers schedule these crops to meet critical market windows and determine the impacts of changing the growing temperature on crop timing and quality.
Crocins comprise a family of hydrophilic carotenoids with pharmacological properties that are produced in significant quantities in stigma of Crocus sativus. Although the biosynthesis pathway of crocins has been sufficiently elucidated, there is a paucity of information regarding how transcription factors (TFs) regulate crocin biosynthesis in various stigma developmental stages. WRKY TFs play a role in modulating carotenoid/apocarotenoid metabolism. To provide an overview of the WRKY family in Crocus sativus (CsWRKY) and characterize candidate CsWRKY TFs involved in the biosynthesis of crocins, CsWRKY genes were identified from RNA-sequenced stigma at different developmental stages. A phylogenetic analysis was performed to characterize their evolutionary interrelatedness. A coexpression analysis of CsWRKY genes and crocin biosynthesis-related genes was performed. A quantitative real-time polymerase chain reaction was used to corroborate the expression level of CsWRKY TFs in various tissue and at different developmental stages. A total of 34 CsWRKY TFs were identified from the stigma of C. sativus. The CsWRKY TFs, together with their orthologs from Arabidopsis, were clustered into group I, II, or III following phylogenetic analysis. A correlation analysis revealed that the expressions of the TFs CsWRKY1, CsWRKY2, CsWRKY8, CsWRKY10, CsWRKY15, and CsWRKY28 were strongly related to the expression of crocin biosynthesis-related genes CsBCH, CsCCD2L, CsALDH, and CsUGT. CsWRKY2, CsWRKY15, and CsWRKY28 exhibited identical motifs and were stratified into group IId. Transcript levels of candidate CsWRKY genes were higher in stigma than in other tissues and were proportional to the crocin content.
Chinese Artichoke (Stachys sieboldii Miq.), an indigenous vegetable in China, is renowned for its rich nutritional content and medicinal properties. With a significant cultivation history and promising prospects, this vegetable holds great potential for further development. In this study, we investigated changes in gene expression levels and metabolite content within relevant metabolic pathways during the development of Chinese Artichoke tubers. Tubers from three different periods—S1 (6 Aug), S2 (2 Sep), and S3 (1 Oct)—served as materials for the analysis. The results revealed that differentially expressed genes and differentially accumulated metabolites were predominantly enriched in pathways associated with secondary metabolite synthesis, carbohydrate metabolism, amino acid metabolism, and lipid metabolism. These pathways are known to play significant regulatory roles in the development of Chinese Artichoke tubers. Two crucial metabolic pathways identified through a comprehensive analysis of transcriptomics and metabolomics were further investigated. The genes GOLS, STS, AGAL, and INV potentially play crucial roles in stachyose accumulation. Additionally, the genes trpB (Cluster-5100.0), GOT2 (Cluster-7051.0), and TYRAAT (Cluster-4023.14777) potentially influence the aromatic amino acid content at different developmental stages. However, the regulatory mechanisms of these genes and their relationship with metabolites require further investigation. The study findings provide a theoretical foundation for understanding the key pathways that influence the growth of Chinese Artichoke tubers, metabolic mechanisms of stachyose and amino acids, verification of gene functions, and genetic enhancement of Chinese Artichoke cultivars.
γ-Aminobutyric acid (GABA), a nonprotein amino acid, can accumulate in plants in response to abiotic stresses. The effects of postharvest treatments on endogenous GABA concentrations and exogenous GABA on whole horticulture product quality has recently received attention. However, knowledge of the effects of mechanical damage events such as peeling and cutting on GABA concentrations of fresh-cut products is limited. In this study, concentrations of GABA and antioxidants including total phenolics and ascorbic acid in fresh-cut cantaloupe, pineapple, and cauliflower during storage at 5 °C for 9 days were investigated. We found that GABA accumulated in fresh-cut pineapple and cauliflower during storage, but that the increase in cantaloupe was not significant. Total phenolics, total ascorbic acid, and dehydroascorbic acid (DHA) remained stable in fresh-cut cantaloupe and cauliflower. In pineapple, however, total phenolics and total ascorbic acid concentrations decreased, whereas the DHA concentration increased. No correlation was found between GABA and antioxidants in fresh-cut cauliflower and cantaloupe; however, GABA was negatively related to antioxidants, including total phenolics and total ascorbic acid, in fresh-cut pineapple. The results show that GABA accumulation may represent a stress response to damage that occurs during the preparation of fresh cut products, but that the degree of response is affected by the specific product. Further research of GABA metabolism in response to minimal processing, including GABA biosynthesis, in a wider range of horticultural products and relationships with antioxidants is warranted.
As anthropogenic activities have facilitated the spread of heavy metals into the environment, plants have been identified that may have the ability to tolerate exposure to high levels of these metals. Industrial hemp (Cannabis sativa L.) has been suggested as potentially having the ability to accumulate elevated concentrations of some contaminants from soils, including cadmium (Cd), a heavy metal that has been linked to serious health risks to humans. Therefore, there is an interest to document the ability of hemp to tolerate exposure to Cd to determine if there is a risk when products for medicinal consumption are made from the hemp plant. The objectives of this study were to perform histochemical localization of Cd at the cellular level and document potential changes in plant tissues in response to hemp exposure. Plants were grown in hydroponic solutions for 4 weeks and then exposed to either 0 or 10 mg·L−1 Cd for 17 days and harvested. There were no differences in dry weights (dw) of leaves, stems, and roots among treated and control 17 days after treatment (DAT). However, plants exposed to 10 mg·L−1 Cd had Cd concentrations of 1448.0 mg·kg−1 dw in roots and 23.2 mg·kg−1 dw in leaves at 17 DAT, whereas Cd was not detected in roots or leaves of control plants. On staining with dithizone, Cd was primarily localized in leaf epidermis, mesophyll, and trichomes, and in root rhizodermis, cortex, and pericycle in hemp plants exposed to 10 mg·L−1 Cd. Image analysis was able to further quantify these results based on area stained. Our results suggest that Cd is primarily accumulated throughout hemp roots, with lesser amounts translocated to the leaves, where it may be localized in the epidermis and trichomes.