This review contains functional roles of MYB transcription factors in the transcriptional regulation of anthocyanin biosynthesis in horticultural plants This review describes potential uses of MYB TFs as tools for metabolic engineering for anthocyanin production Anthocyanins (ranging from red to blue) are controlled by specific branches of the anthocyanin biosynthetic pathway and are mostly visible in ornamentals, fruits, and vegetables In the present review, we describe which R2R3-MYB transcription factors (TFs) control the transcriptional regulation of anthocyanin structural genes involved in the specific branches of the anthocyanin biosynthetic pathway in various horticultural plants (eg, ornamentals, fruits, and vegetables) In addition, some MYBs responsible for anthocyanin accumulation in specific tissues are described Moreover, we highlight the phylogenetic relationships of the MYBs that suppress or promote anthocyanin synthesis in horticultural crops Enhancement of anthocyanin synthesis via metabolic genetic engineering of anthocyanin MYBs, which is described in the review, is indicative of the potential use of the mentioned anthocyanin-related MYBs as tools for anthocyanin production Therefore, the MYBs would be suitable for metabolic genetic engineering for improvement of flower colors, fruit quality, and vegetable nutrients

Roles of R2R3-MYB transcription factors in transcriptional regulation of anthocyanin biosynthesis in horticultural plants

Understanding the genetic regulation of anthocyanin biosynthesis in plants - Tools for breeding purple varieties of fruits and vegetables.

Immature, vegetable-like fruits are produced by crops of great economic importance, including cucumbers, zucchini, eggplants and bell peppers, among others. Because of their high respiration rates, associated with high rates of dehydration and metabolism, and their susceptibility to chilling injury (CI), vegetable fruits are highly perishable commodities, requiring particular storage conditions to avoid postharvest losses. This review focuses on the oxidative stress that affects the postharvest quality of vegetable fruits under chilling storage. We define the physiological and biochemical factors that are associated with the oxidative stress and the development of CI symptoms in these commodities, and discuss the different physical, chemical and biotechnological approaches that have been proposed to reduce oxidative stress while enhancing the chilling tolerance of vegetable fruits.

Oxidative Stress Associated with Chilling Injury in Immature Fruit: Postharvest Technological and Biotechnological Solutions.

Background Owing to the postharvest mass loss in most tropical and subtropical fruits and vegetables caused by chilling injury (CI), it is necessary to look for effective technologies to alleviate this issue. Studies thus far have found that some postharvest technologies could effectively alleviate CI in post-harvest fruits and vegetables. Scope and approach This review summarizes the temperature and symptoms of CI in common postharvest fruits and vegetables. The postharvest technologies to control CI, which comprised physical (low-temperature conditioning, heat treatment, near-freezing temperature, controlled atmosphere, edible coating and ultraviolet irradiation) and chemical (ethylene and 1-methylcyclopropene, oxalic acid, calcium ions, nitric oxide, melatonin, salicylates and jasmonates, polyamines, and some other chemical substances) treatments, are also detailed. The potential biochemical mechanisms of different postharvest technologies are also proposed and attributed to the following strategies: maintaining membrane structure and sufficient energy supply, enhancing the antioxidant system, promoting the arginine pathway, regulating sugar metabolism, and activating the C-repeat/dehydration response element binding factor (CBF) genes. Key findings and conclusions This review found that a variety of postharvest treatments have been developed to control CI in postharvest fruits and vegetables. The key findings were that the effects of some postharvest treatments—such as ethylene and 1-methylcyclopropene—on fruit and vegetable CI are contradictory. Some key factors, such as the time and temperature of heat treatment and the dose of ultraviolet radiation, need to be regarded when applying postharvest technologies. Some small-molecule signal substances that from natural plant and the combination of different treatments are potential future research directions for controlling CI in postharvest fruits and vegetables.

Advances in biochemical mechanisms and control technologies to treat chilling injury in postharvest fruits and vegetables

Flavonoids represent a wide group of plant secondary metabolites implicated in many physiological roles, from the attraction of pollinators to the protection against biotic or abiotic stresses. Flavonoids are synthetized in a number of horticultural crops that are important components of our daily diet. In the last decades, the consumption of vegetables rich in antioxidants has been strongly promoted from the perspective of prevention/protection against chronic diseases. Therefore, due to their nutritional importance, several attempts have been made to enhance flavonoid levels in species of agronomic interest. In this review, we focus on the flavonoid biodiversity among the major horticultural species, which is responsible of differences among closely related species and influences the qualitative/quantitative composition. We also review the role of flavonoids in the nutritional quality of plant products, contributing to their organoleptic and nutritional properties, and the main strategies of biofortification to increase their content.

https://www.mdpi.com/2223-7747/7/4/98/pdf

Looking at Flavonoid Biodiversity in Horticultural Crops: A Colored Mine with Nutritional Benefits.

Anthocyanins, natural pigments with high antioxidant activities, are widely distributed in the plant kingdom and play important roles in various physiological processes. Much effort has been committed to enhancing the anthocyanin content of these health-promoting pigments in vegetables and grains, for their eye-catching colors and special nutrients. Previously, we reported that the SmMYB1 gene encoding a R2R3 MYB transcription factor participated in the regulation of anthocyanin biosynthesis in the peel of eggplant. In this work, we introduced SmMYB1 into a non-anthocyanin-accumulating eggplant cultivar (Solanum aethiopicum group Gilo) via Agrobacterium-mediated transformation. Genetically engineered plants exhibited high concentrations of anthocyanin in leaves, petals, stamens, and fruit peels under normal growth conditions, especially in fruit flesh. Furthermore, highly methylated anthocyanins, malvidin 3-(p-coumaroyl)rhamnoside(glucoside)-5-glucoside and malvidin 3-(feruloyl)rhamnoside(glucoside)-5-glucoside, were separated from the purple fruit flesh and identified by HPLC–ESI–MS/MS. qRT-PCR analysis revealed that most anthocyanin structural genes were dramatically up-regulated in the tissues of transgenic lines compared with non-transformed plants. In addition, the transgenic seedlings had greater tolerance to freezing stress and better recovery under rewarming conditions. These results provide a good foundation for the breeding of new eggplant cultivars with more healthy agronomic traits in future studies.

Bo Wang

Papers

Genetically engineered anthocyanin pathway for high health-promoting pigment production in eggplant