Transcription factors DkBZR1/2 regulate cell wall degradation genes and ethylene biosynthesis genes during persimmon fruit ripening.

BRASSINAZOLE RESISTANT (BZR) transcription factors are critical components of the brassinosteroid signalling pathway, but their possible roles in fruit ripening have rarely been reported. In this study, four BZR sequences were isolated from persimmon fruit. Among the four BZR genes, DkBZR1/2 were expressed in persimmon fruit; DkBZR1 protein amount decreased and dephosphorylated DkBZR2 gradually accumulated during the storage period.

Genome-wide analysis of the bZIP gene family and the role of AchnABF1 from postharvest kiwifruit (Actinidia chinensis cv. Hongyang) in osmotic and freezing stress adaptations.

Chilling injury (CI) is a barrier to the refrigeration of kiwifruit, resulting in decreased fruit quality and increased nutrient loss during storage. Understanding the molecular basis underlying the cold response and its regulation in refrigerated kiwifruit is therefore highly important. Basic (region) leucine zipper (bZIP) transcription factors (TFs) have been widely studied for their roles in abiotic stress resistance in various species.

Effects of calcium treatment on malate metabolism and γ-aminobutyric acid (GABA) pathway in postharvest apple fruit.

Calcium treatment effects on malate metabolism and the GABA pathway in 'Cripps Pink' apple fruit during storage were investigated. Postharvest apple fruit treated with 1% and 4% calcium chloride solutions were stored at 25 ± 1 °C. The 4% calcium treatment suppressed declines in titratable acidity and malate content and increased succinate and oxalate concentrations.

Exogenous γ-Aminobutyric Acid Treatment That Contributes to Regulation of Malate Metabolism and Ethylene Synthesis in Apple Fruit during Storage.

Organic acid is an important indicator of fruit quality, and malate is the predominant organic acid in apple fruit. However, the regulation of malate metabolism in postharvest fruit is rarely reported. Here, we found that, compared with a control treatment, a 10 mM γ-aminobutyric acid (GABA) treatment remarkably delayed the loss of tiftratable acidity and malate and increased the succinate and oxalate contents in "Cripps Pink" fruit stored in polyethylene bags at room temperature.

Differences in 1-methylcyclopropene sorption dynamics in fresh-cut apple, avocado and tomato fruits.

Fresh-cut (FC) apple, avocado and tomato fruits were examined to determine if sorption dynamics previously reported for FC apple were of general occurrence for other fruits. Fresh-cut apple consumed headspace 1-MCP at high rates, fully depleting 1-MCP in 1.5 h.

Functional characterization of persimmon β-galactosidase gene DkGAL1 in tomato reveals cell wall modification related to fruit ripening and radicle elongation.

Cell wall metabolism during fruit ripening is a highly organized process that involves complex interplay among various cell wall hydrolases. Among these cell wall hydrolases, β-galactosidase has been identified to participate in cell wall metabolism via its ability to catalyze galactosyl metabolism from the large and complex side chains of cell walls. In this study, the galactose content in the pericarp increased during persimmon fruit ripening, but cell wall galactosyl residues decreased, indicating a relationship between galactose metabolism and persimmon fruit ripening.

Role of Brassinosteroids in Persimmon ( Diospyros kaki L.) Fruit Ripening.

Brassinosteroids (BRs) are phytohormones that regulate numerous processes including fruit ripening. In this study, persimmon ( Diospyros kaki L.) fruits were treated with 24-epibrassinolide (EBR) or brassinazole (Brz, a BR biosynthesis inhibitor) and then stored at ambient temperature.

Exploring the Functions of 9-Lipoxygenase (DkLOX3) in Ultrastructural Changes and Hormonal Stress Response during Persimmon Fruit Storage.

Lipoxygenase (LOX) initiates the hydroperoxidation of polyunsaturated fatty acids and is involved in multiple physiological processes. In this study, investigation of various microscopic techniques showed that the fruit peel cellular microstructure of the two persimmon cultivars differed after 12 days of storage, resulting in fruit weight loss and an increased number and depth of microcracks. Analysis of subcellular localization revealed that greater amounts of DkLOX3-immunolabelled gold particles accumulated in "Fupingjianshi" than in "Ganmaokui" during storage.

Overexpression of persimmon DkXTH1 enhanced tolerance to abiotic stress and delayed fruit softening in transgenic plants.

DkXTH1 promoted cell elongation and more strength to maintain structural integrity by involving in cell wall assembly, thus enhanced tolerance to abiotic stress with broader phenotype in transgenic plants. Xyloglucan endotransglucosylase/hydrolase (XTH) is thought to play a key role in cell wall modifications by cleaving and re-joining xyloglucan, and participates in the diverse physiological processes. DkXTH1 was found to peak in immature expanding persimmon fruit, and its higher expression level exhibited along with firmer fruit during storage.

DkXTH8, a novel xyloglucan endotransglucosylase/hydrolase in persimmon, alters cell wall structure and promotes leaf senescence and fruit postharvest softening.

Fruit softening is mainly associated with cell wall structural modifications, and members of the xyloglucan endotransglucosylase/hydrolase (XTH) family are key enzymes involved in cleaving and re-joining xyloglucan in the cell wall. In this work, we isolated a new XTH gene, DkXTH8, from persimmon fruit. Transcriptional profiling revealed that DkXTH8 peaked during dramatic fruit softening, and expression of DkXTH8 was stimulated by propylene and abscisic acid but suppressed by gibberellic acid and 1-MCP.

Effect of Putrescine Treatment on Chilling Injury, Fatty Acid Composition and Antioxidant System in Kiwifruit.

We investigated the effects of different concentrations (0, 1, 2 and 4 mM) of putrescine on chilling injury, fruit quality, ethylene production rate, fatty acid composition and the antioxidant system of cold-stored kiwifruit (Actinidia chinensis Planch. var. chinensis 'Hongyang').

Isolation and Characterization of Two Persimmon Xyloglucan Endotransglycosylase/Hydrolase (XTH) Genes That Have Divergent Functions in Cell Wall Modification and Fruit Postharvest Softening.

Fruit cell wall modification is the primary factor affecting fruit softening. Xyloglucan endotransglycosylase/hydrolase (XTH), a cell wall-modifying enzyme, is involved in fruit softening. In this study, two novel XTH genes (DkXTH6 and DkXTH7) were identified from persimmon fruit.

The Persimmon 9-lipoxygenase Gene DkLOX3 Plays Positive Roles in Both Promoting Senescence and Enhancing Tolerance to Abiotic Stress.

The lipoxygenase (LOX) pathway is a key regulator for lipid peroxidation, which is crucial for plant senescence and defense pathways. In this study, the transcriptional expression patterns of three persimmon (Diospyros kaki L. 'Fupingjianshi') 9-lipoxygenase genes (DkLOX1, DkLOX3, and DkLOX4) were investigated.

Analysis of xyloglucan endotransglycosylase/hydrolase (XTH) genes and diverse roles of isoenzymes during persimmon fruit development and postharvest softening.

Xyloglucan endotransglycosylase/hydrolase (XTH) enzymes have played a role in the remodeling of cell wall hemicelluloses. To investigate the function of XTHs in persimmon (Diospyros kaki L.) fruit development and postharvest softening, five cDNAs (DkXTH1 to DkXTH5), whose putative proteins contained the conserved DEIDFEFLG motif of XTH, were cloned.

A Petunia homeodomain-leucine zipper protein, PhHD-Zip, plays an important role in flower senescence.

Flower senescence is initiated by developmental and environmental signals, and regulated by gene transcription. A homeodomain-leucine zipper transcription factor, PhHD-Zip, is up-regulated during petunia flower senescence. Virus-induced gene silencing of PhHD-Zip extended flower life by 20% both in unpollinated and pollinated flowers.

Low-temperature conditioning induces chilling tolerance in 'Hayward' kiwifruit by enhancing antioxidant enzyme activity and regulating en-dogenous hormones levels.

Background: To understand the mechanisms leading to the enhanced chilling tolerance of kiwifruit by low-temperature conditioning (LTC, 12 °C for 3 days), this study investigated the effect of LTC on chilling tolerance and changes in antioxidant enzyme activities and endogenous hormones.

Results: LTC significantly alleviated chilling injury in kiwifruit. Fruits treated with LTC maintained lower respiration and ethylene production and higher firmness.

Identification of xyloglucan endotransglucosylase/hydrolase genes (XTHs) and their expression in persimmon fruit as influenced by 1-methylcyclopropene and gibberellic acid during storage at ambient temperature.

Xyloglucan endotransglucosylase/hydrolase (XTH) is thought to contribute to fruit softening by degrading xyloglucan that is a predominant hemicellulose in the cell wall. In this study, two full-length XTH genes (DKXTH1 and DKXTH2) were identified from 'Fupingjianshi' persimmon fruit, and the expression level of both XTH genes was investigated during softening for 18-24 d using RT-qPCR. Sequence analysis showed that DKXTH1 and DKXTH2 contained a putative open reading frame of 861 and 876 bp encoding polypeptides of 287 and 292 amino acid residues, respectively, which contained the conserved DEIDFEFLG motif of XTH, a potential N-linked glycosylation signal site.