CBL1/CIPK23 phosphorylates tonoplast sugar transporter TST2 to enhance sugar accumulation in sweet orange (Citrus sinensis).

Fruit taste quality is greatly influenced by the content of soluble sugars, which are predominantly stored in the vacuolar lumen. However, the accumulation and regulation mechanisms of sugars in most fruits remain unclear. Recently, we established the citrus fruit vacuole proteome and discovered the major transporters localized in the vacuole membrane.

Vacuolar proteomic analysis reveals tonoplast transporters for accumulation of citric acid and sugar in citrus fruit.

Vacuole largely dictates the fruit taste and flavor, as most of the sugars and organic acids are stored in the vacuoles of the fruit. However, difficulties associated with vacuole separation severely hinder identification and characterization of vacuolar proteins in fruit species. In this study, we established an effective approach for separating vacuoles and successfully purified vacuolar protein from six types of citrus fruit with varying patterns of sugar and organic acid contents.

The regulatory module MdBZR1-MdCOL6 mediates brassinosteroid- and light-regulated anthocyanin synthesis in apple.

The anthocyanin content is an important indicator of the nutritional value of most fruits, including apple (Malus domestica). Anthocyanin synthesis is coordinately regulated by light and various phytohormones. In this study on apple, we revealed the antagonistic relationship between light and brassinosteroid (BR) signaling pathways, which is mediated by BRASSINAZOLE-RESISTANT 1 (MdBZR1) and the B-box protein MdCOL6.

MdERF1B-MdMYC2 module integrates ethylene and jasmonic acid to regulate the biosynthesis of anthocyanin in apple.

Ethylene and jasmonic acid (JA) are crucial hormones that promote anthocyanin synthesis in apple ( × ) However, the mechanism by which these hormones cooperate to modulate anthocyanin production in apple is unclear. According to our results, expression was strongly induced by ethylene and JA. Physiological phenotypes and the results of molecular biological analyses indicated that encodes a positive regulator of anthocyanin synthesis.

Transcription factor McWRKY71 induced by ozone stress regulates anthocyanin and proanthocyanidin biosynthesis in Malus crabapple.

In plants, anthocyanins and proanthocyanidins (PAs) play important roles in plant resistance to abiotic stress. In this study, ozone (O) treatments caused the up-regulation of Malus crabapple structural genes McANS, McCHI, McANR and McF3H, which promoted anthocyanin and PA accumulation. We identified the WRKY transcription factor (TF) McWRKY71 by screening differentially expressed genes (DEGs) that were highly expressed in response to O stress from an RNA sequencing (RNA-seq) analysis.

Brassinolide inhibits flavonoid biosynthesis and red-flesh coloration via the MdBEH2.2-MdMYB60 complex in apple.

Flavonoid content, which is an important indicator of the nutritional value of fruits and vegetables, directly determines the marketability of many fruit crops, including apple (Malus domestica). Brassinosteroids (BRs) are steroid hormones that affect flavonoid biosynthesis in plants, but the underlying regulatory mechanism remains unclear. In this study, treatments with brassinolide (the most active BR) and brassinazole (a BR biosynthesis inhibitor) decreased and increased, respectively, the flavonoid, anthocyanin, and proanthocyanidin (PA) content in red-fleshed apple seedlings and calli.

The MdHY5-MdWRKY41-MdMYB transcription factor cascade regulates the anthocyanin and proanthocyanidin biosynthesis in red-fleshed apple.

Red-fleshed apple fruits are popular because of their high flavonoid content. Although MdMYB10 and its homologs have been identified as crucial regulators of the fruit coloring process, other transcription factors (TFs) contributing to the differences in flesh coloration have not been fully characterized. In this study, we investigated the regulatory effects of MdWRKY41 on anthocyanin and proanthocyanidin (PA) synthesis in red-fleshed apples.

Ethylene increases the cold tolerance of apple via the MdERF1B-MdCIbHLH1 regulatory module.

Cold stress has always been a major abiotic factor affecting the yield and quality of temperate fruit crops. Ethylene plays a critical regulatory role in the cold stress response, but the underlying molecular mechanisms remain elusive. Here, we revealed that ethylene positively modulates apple responses to cold stress.

Interaction between MdMYB63 and MdERF106 enhances salt tolerance in apple by mediating Na/H transport.

Salt stress is an important environmental factor affecting the growth and production of agricultural crops and fruits worldwide, including apple (Malus × domestica). In this study, we demonstrate that a salt-responsive MYB transcription factor (TF), designated as MdMYB63, promotes survival under salt stress. Overexpression of MdMYB63 in apple calli significantly enhanced salt tolerance.

Ultraviolet B-induced MdWRKY72 expression promotes anthocyanin synthesis in apple.

Ultraviolet-B (UV-B) radiation promotes anthocyanin synthesis in many plants. Although several transcription factors promote anthocyanin synthesis in response to UV-B radiation, the underlying mechanism remains unclear. In this study, the MdWRKY72 transcription factor gene was isolated from the 'Taishanzaoxia' apple genome.

The R2R3-MYB transcription factor MdMYB24-like is involved in methyl jasmonate-induced anthocyanin biosynthesis in apple.

Anthocyanins in apple species are important secondary metabolites that are beneficial for human health. Previous studies revealed that methyl jasmonate (MeJA) promotes anthocyanin accumulation by up-regulating the transcription of related genes. In this study, we isolated a jasmonate (JA)-induced apple MYB gene, MdMYB24-like (MdMYB24L).

A feedback loop involving MdMYB108L and MdHY5 controls apple cold tolerance.

The MYB transcription factors are important for many aspects of plant stress responses. In this study, we isolated and identified an apple MYB gene, MdMYB108L, whose expression is induced by light and cold stresses. An analysis of MdMYB108L-overexpressing transgenic apple calli revealed that MdMYB108L enhances cold tolerance in apple by upregulating MdCBF3 expression.