Melatonin (MLT) is a vital signaling molecule that regulates multiple physiological processes in higher plants. In the current study, the role of MLT in regulating chilling tolerance and its possible ...mechanisms in litchi fruit during storage at ambient temperatures after its removal from refrigeration was investigated. The results show that the application of MLT (400 μM, dipping for 20 min) to 'Baitangying' litchi fruit effectively delayed the development of chilling injury (CI) while inhibiting pericarp discoloration, as indicated by higher chromacity values (
,
,
) and anthocyanin levels. MLT treatment suppressed the enhancements of the relative electrical conductivity (REC) and malondialdehyde (MDA) content, which might contribute to the maintenance of membrane integrity in litchi fruit. MLT treatment slowed the decline in cellular energy level, as evidenced by higher adenosine triphosphate (ATP) content and a higher energy charge (EC), which might be ascribed to the increased activities of enzymes associated with energy metabolism including H
-ATPase, Ca
-ATPase, succinate dehydrogenase (SDH), and cytochrome C oxidase (CCO). In addition, MLT treatment resulted in enhanced proline accumulation, which was likely a consequence of the increased activities of ornithine-δ-aminotransferase (OAT) and Δ
-pyrroline-5-carboxylate synthase (P5CS) and the suppressed activity of proline dehydrogenase (PDH). These results suggest that the enhanced chilling tolerance of litchi fruit after MLT treatment might involve the regulation of energy and proline metabolism.
Fruit softening that occurs during fruit ripening and postharvest storage determines the fruit quality, shelf life and commercial value and makes fruits more attractive for seed dispersal. In ...addition, over-softening results in fruit eventual decay, render fruit susceptible to invasion by opportunistic pathogens. Many studies have been conducted to reveal how fruit softens and how to control softening. However, softening is a complex and delicate life process, including physiological, biochemical and metabolic changes, which are closely related to each other and are affected by environmental conditions such as temperature, humidity and light. In this review, the current knowledge regarding fruit softening mechanisms is summarized from cell wall metabolism (cell wall structure changes and cell-wall-degrading enzymes), plant hormones (ETH, ABA, IAA and BR et al.), transcription factors (MADS-Box, AP2/ERF, NAC, MYB and BZR) and epigenetics (DNA methylation, histone demethylation and histone acetylation) and a diagram of the regulatory relationship between these factors is provided. It will provide reference for the cultivation of anti-softening fruits.
The 26S proteasome is an ATP-dependent proteolytic complex in eukaryotes, which is mainly responsible for the degradation of damaged and misfolded proteins and some regulatory proteins in cells, and ...it is essential to maintain the balance of protein levels in the cell. The ubiquitin-26S proteasome pathway, which targets a wide range of protein substrates in plants, is an important post-translational regulatory mechanism involved in various stages of plant growth and development and in the maturation process of fleshy fruits. Fleshy fruit ripening is a complex biological process, which is the sum of a series of physiological and biochemical reactions, including the biosynthesis and signal transduction of ripening related hormones, pigment metabolism, fruit texture changes and the formation of nutritional quality. This paper reviews the structure of the 26S proteasome and the mechanism of the ubiquitin-26S proteasome pathway, and it summarizes the function of this pathway in the ripening process of fleshy fruits.
Tomato serves as the model plant for studying fruit ripening and quality formation including pigment, texture, flavor, aroma and nutrition. The ripening of tomato fruit results from the selective ...expression of ripening-related genes, which are strictly regulated by transcription factors (TFs), such as RIPENING INHIBITOR (RIN), NON-RIPENING (NOR) and COLORLESS NON-RIPENING (CNR). Understanding the transcriptional network has important biological significance for the fruit ripening regulation, which can help improve fruit quality and commodity value, and improve the utilization of agricultural resources. The molecular mechanism of TF control, a redundant regulatory network, has been extensively studied thanks to advancements in scientific research technologies. Here, we focus on the synergistic or antagonistic regulation of TFs in tomato fruit ripening, including the relationship between TFs and the regulatory patterns of ripening-related target genes, which is supported by sufficient evidence.
•Tomato serves as the model plant for studying fruit quality formation.•Fruit quality formation is regulated by a series of transcription factors.•Interactions between transcription factors related to fruit quality.
•Melatonin inhibited litchi downy blight caused by Peronophythora litchii in litchis.•Melatonin activated phenylpropanoid and pentose phosphate pathways in litchis.•Melatonin maintained higher energy ...status by promoting energy metabolism in litchis.•The metabolic changes induced by melatonin contributed to enhanced fruit resistance.
Litchis are tasty fruit with economic importance. However, the extreme susceptibility of harvested litchis to litchi downy blight caused by Peronophythora litchii leads to compromised quality. This study aimed to study the effects of melatonin on postharvest resistance to P. litchii in ‘Feizixiao’ litchis. Results showed that melatonin restricted lesion expansion in litchis after P. litchi inoculation. Melatonin enhanced the activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase and 4-hydroxycinnamate CoA ligase while promoting the accumulations of phenolics and flavonoids. Nicotinamide adenine dinucleotide phosphate content and glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid dehydrogenase activities were higher in treated fruit than control fruit. Higher energy status along with elevated H+-ATPase, Ca2+-ATPase, succinate dehydrogenase and cytochrome C oxidase activities were observed in treated fruit. Ultrastructural observation showed reduced damage in mitochondria in treated fruit. The results suggest that melatonin induced resistance in litchis by modulating the phenylpropanoid and pentose phosphate pathways as well as energy metabolism.
.
Main conclusion
NOR-like1 regulates tomato fruit size by targeting
SlARF9
,
SlGRAS2
,
SlFW3
.2, and
SlFW11
.3 genes involved in cell division and cell expansion.
Fruit size is an important ...agricultural character that determines the yield of crops. Here, we found that NAC transcription factor NOR-like1 regulated fruit size by regulating cell layer number and cell area in tomato. Over-expressing
NOR-like1
gene in tomato reduced fruit weight and size, whereas the knock-out of
NOR-like1
increased fruit weight and size. At the molecular level, NOR-like1 binds to the promoter of
SlGRAS2
,
SlFW3
.2, and
SlFW11
.3 to repress their transcription, while it also binds to the promoter of
ARF9
to activate its transcription
.
Overall, these results expand the biological function of NOR-like1 and deepen our understanding of the transcriptional network that regulates tomato fruit size.
•Nitric oxide (NO) inhibited anthracnose, Colletotrichum gloeosporioides, in pitaya fruit.•NO enhanced defense responses and delayed senescence in pitaya fruit.•NO treatment could be a promising ...approach to control anthracnose in pitaya fruit.
The effect of nitric oxide (NO) on resistance of pitaya fruit against anthracnose caused by Colletotrichum gloeosporioides and its related mechanisms were investigated in this study. ‘Baiyulong’ pitaya fruit were immersed in 0.1 mM sodium nitroprusside (a NO donor) for 8 min, inoculated with spore suspension of C. gloeosporioides after 24 h of NO treatment, and then stored at 25 °C for up to 8 days. NO treatment markedly inhibited the lesion expansion on pathogen-inoculated pitaya fruit during storage. NO treatment also reduced the natural disease incidence and index of pitaya fruit stored at 25 °C. Furthermore, NO treatment increased the activities of defense-related enzymes including phenylalanine ammonia-lyase (PAL), CoA ligase (4CL), peroxidase (POD), polyphenol oxidase (PPO), chitinase (CHI) and β-1,3-glucanase (GLU), as well as elevated the contents of antifungal compounds including total phenolics, flavonoids and lignin. In addition, NO treatment reduced respiration rate and weight loss, while delayed the declines of firmness and soluble solids content (SSC). These results indicate that NO could effectively enhance the resistance of pitaya fruit to anthracnose, which might be ascribed to activation of defense responses and retardation of senescence.
Chilling injury (CI) is a bottleneck factor constraining the refrigeration and cold chain logistics of mango fruit. Methyl jasmonate (MeJA) is an important phytohormone that can regulate multiple ...abiotic stresses. This study evaluated the potential effects of MeJA on CI in ‘Guifei’ mango fruit stored at 4 °C and its underlying mechanisms involved in the regulation of antioxidation and energy status. The application of 50 µM MeJA mitigated CI symptoms and improved ripening-related quality during refrigeration, as indicated by a lowered CI index, retarded declines in chlorophyll fluorescence (Fv/Fm) and chromaticity L* and advanced color transformation (from green to yellow), softening and accumulation of soluble solids. MeJA treatment repressed the increases in relative conductivity (RC), malondialdehyde (MDA) content and reactive oxygen species (ROS) (O2-. and H2O2). Reduced ROS generation in MeJA-treated fruit was a consequence of the enhancement of antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). Ultrastructural observation revealed that MeJA treatment protected mitochondrial structure. MeJA treatment promoted intracellular energy synthesis and utilization, as indicated by increments in intracellular adenosine triphosphate (iATP) level, activities of isocitrate dehydrogenase (IDH), α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), H+-ATPase and Ca2+-ATPase as well as contents of reduced coenzymes (NADH and FADH2). In addition, the expression levels of genes (MiAPYs, MiENTs, MiPUPs and MiAPRTs) related to extracellular ATP (eATP) hydrolysis, eATP transport and iATP regeneration were upregulated in response to MeJA, contributing to maintenance of eATP/iATP homeostasis. These findings suggest that MeJA could reinforce cold tolerance in mango fruit by inhibiting oxidative stress and promoting energy metabolism.
•Methyl jasmonate (MeJA) relieved chilling injury in mango fruit during cold storage.•MeJA increased the activities of antioxidant enzymes in mango fruit.•MeJA protected mitochondrial structure and promoted energy synthesis in mango fruit.•MeJA enhanced activities of mitochondrial H+-ATPase and Ca2+-ATPase in mango fruit.•MeJA maintained eATP/iATP homeostasis by regulating iATP salvage pathways.
In flowering plants, sepals play important roles in the development of flowers and fruit, and both processes are regulated by MADS-box (MADS) transcription factors (TFs). SlMADS1 was previously ...reported to act as a negative regulator of fruit ripening. In this study, expression analysis shown that its transcripts were very highly expressed during the development of sepals. To test the role of SlMADS1, we generated KO-SlMADS1 (knock-out) tomato mutants by CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9) technology and over-expression of SlMADS1 (OE-SlMADS1). The sepals and individual cells of KO-SlMADS1 mutants were significantly elongated, compared with the wild type (WT), whereas the sepals of OE-SlMADS1 tomatoes were significantly shorter and their cells were wider. RNA-seq (RNA-sequencing) of sepal samples showed that ethylene-, gibberellin-, auxin-, cytokinin- and cell wall metabolism-related genes were significantly affected in both KO-SlMADS1 and OE-SlMADS1 plants with altered sepal size. Since SlMACROCALYX (MC) is known to regulate the development of tomato sepals, we also studied the relationship between SlMC and SlMADS1 and the result showed that SlMADS1 interacts directly with SlMC. In addition, we also found that manipulating SlMADS1 expression alters the development of tomato plant leaves, roots and plant height. These results enrich our understanding of sepal development and the function of SlMADS1 throughout the plant.
•SlMADS1 is highly expressed during the development of sepals.•The sepals and individual cells of KO-SlMADS1 mutants are significantly elongated and the inverse phenotypes are detected in OE-SlMADS1 lines.•SlMADS1 interacts with MACROCALYX (MC).•Manipulating SlMADS1 expression alters the sepal length of tomato fruit.
Abstract
With the development of bioinformatics, it is easy to obtain information and data about thousands of genes, but the determination of the functions of these genes depends on methods for rapid ...and effective functional identification. Virus-induced gene silencing (VIGS) is a mature method of gene functional identification developed over the last 20 years, which has been widely used in many research fields involving many species. Fruit quality formation is a complex biological process, which is closely related to ripening. Here, we review the progress and contribution of VIGS to our understanding of fruit biology and its advantages and disadvantages in determining gene function.
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