Transcriptomic study of pedicels from GA3-treated table grape genotypes with different susceptibility to berry drop reveals responses elicited in cell wall yield, primary growth and phenylpropanoids synthesis

Pre-harvest treatment with gibberellin (GA3) and nitric oxide donor (SNP) enhances post-harvest firmness of grape berries

Grapes are prone to softening, which limits their shelf life and suitability for long-distance transport. This study explored the molecular mechanisms underlying the effects of the chemical preservatives gibberellin (GA3) and the nitric oxide donor sodium nitroprusside (SNP) on grape firmness. Enhancing grape quality, prolonging shelf life, and extending market supply were key objectives. Using transcriptomic and physicochemical analyses, the study found that treatments with 3 mmol/L GA3 and 20 μmol/L SNP significantly increased the firmness of 'Yinhong' grapes, thereby improving overall quality. The mechanisms of action, however, differed between the two treatments. GA3 inhibited pectin degradation and promoted cellulose accumulation, whereas SNP enhanced lignin and cellulose accumulation, by modulating cell wall metabolism. Furthermore, transcription factors such as CYPs, NAC043, and WRKY33 were identified as key regulators working in concert with target genes to influence berry firmness. These findings highlight the critical roles of GA3 and SNP in improving grape quality and extending storage potential.

Fine mapping and functional validation of the candidate gene BhGA2ox3 for fruit pedicel length in wax gourd (Benincasa hispida)

KEY MESSAGE

The gene regulating fruit pedicel length in wax gourd was finely mapped to a 211 kb region on chromosome 8. The major gene, Bch08G017310 (BhGA2ox3), was identified through forward genetics. Fruit pedicel length (FPL) is a crucial trait in wax gourd (Benincasa hispida) that affects fruit development and cultivation management. However, the key regulatory genes and mechanisms of FPL in wax gourds remain poorly understood. In this study, we constructed an F2 population using wax gourd plants with long fruit pedicels (GF-7-1-1) and short fruit pedicels (YSB-1-1-2) as parents. Through BSA-seq, we initially localised the FPL candidate gene to an 8.4 Mb region on chromosome 8, which was further narrowed down to a 1.1 Mb region via linkage analysis. A large F2 population of 2163 individuals was used to screen for recombinants, and the locus was ultimately narrowed to within a 211 kb (62,299,856-62,511,174 bp) region. Sequence and expression analyses showed that Bch08G017310 (named BhGA2ox3) is a strong candidate gene for FPL in wax gourds. It encodes gibberellin (GA) 2-beta-dioxygenase, a member of the GA 2-oxidase (GA2ox) family. Cytology showed that GA treatment significantly elongated the fruit pedicels and enlarged the cells in the plants with short fruit pedicels. Ectopic expression of BhGA2ox3 showed that BhGA2ox3 overexpression in Arabidopsis thaliana resulted in significantly shorter fruit pedicels. This study lays a theoretical foundation for the regulatory mechanism of FPL in wax gourds and molecular breeding.

Comprehensive analysis of transcriptomics and metabolomics provides insights into the mechanism by plant growth regulators affect the quality of jujube (Ziziphus jujuba Mill.) fruit

A comprehensively analysis of the transcriptomics and metabolomics was conducted to investigate the mechanism of plant growth regulators on the quality of jujube fruit. After the application of plant growth regulators, a total of 3097 differentially expressed genes (DEGs) were identified, which were mainly annotated in 123 pathways such as flavonoid biosynthesis, metabolism of alanine, aspartate, and glutamate. In addition, 1091 differential expressed metabolites (DEMs), including 519 up-regulated and 572 down-regulated metabolites, were significantly altered after application of plant growth regulators. DEGs and DEMs simultaneously annotated 69 metabolic pathways, including biosynthesis of phenylpropane, flavonoid, starch and sucrose. The key genes in flavonoid biosynthesis pathway were revealed, which may play an important role in plant growth regulator regulation quality of jujube fruit. Besides, the application of plant growth regulator during the jujube flowering period increased the contents of gibberellin and indole-3-acetic acid in leaves, and decreased the contents of abscisic acid. The results may help to reveal the metabolic network and molecular mechanism of plant growth regulators in jujube fruit.

Regulatory mechanism of GA3 application on grape (Vitis vinifera L.) berry size

Gibberellin A3 (GA3) is often used as a principal growth regulator to increase plant size. Here, we applied Tween-20 (2%)-formulated GA3 (T1:40 mg/L; T2:70 mg/L) by dipping the clusters at the initial expansion phase of 'Red Globe' grape (Vitis vinifera L.) in 2018 and 2019. Tween-20 (2%) was used as a control. The results showed that GA3 significantly increased fruit cell length, cell size, diameter, and volume. The hormone levels of auxin (IAA) and zeatin (ZT) were significantly increased at 2 h (0 d) -1 d after application (DAA0-1) and remained significantly higher at DAA1 until maturity. Conversely, ABA exhibited an opposite trend. The mRNA and non-coding sequencing results yielded 436 differentially expressed mRNA (DE_mRNAs), 79 DE_lncRNAs and 17 DE_miRNAs. These genes are linked to hormone pathways like cysteine and methionine metabolism (ko00270), glutathione metabolism (ko00480) and plant hormone signal transduction (ko04075). GA3 application reduced expression of insensitive dwarf 2 (GID2, VIT_07s0129g01000), small auxin-upregulated RNA (SAUR, VIT_08s0007g03120) and 1-aminocyclopropane-1-carboxylate synthase (ACS, VIT_18s0001g08520), but increased SAUR (VIT_04s0023g00560) expression. These four genes were predicted to be negatively regulated by vvi-miR156, vvi-miR172, vvi-miR396, and vvi-miR159, corresponding to specific lncRNAs. Therefore, miRNAs could affect grape size by regulating key genes GID2, ACS and SAUR. The R2R3 MYB family member VvRAX2 (VIT_08s0007g05030) was upregulated in response to GA3 application. Overexpression of VvRAX2 in tomato transgenic lines increased fruit size in contrast to the wild type. This study provides a basis and genetic resources for elucidating the novel role of ncRNAs in fruit development.

Plant Development and Crop Yield: The Role of Gibberellins

Gibberellins have been classically related to a few key developmental processes, thus being essential for the accurate unfolding of plant genetic programs. After more than a century of research, over one hundred different gibberellins have been described. There is a continuously increasing interest in gibberellins research because of their relevant role in the so-called "Green Revolution", as well as their current and possible applications in crop improvement. The functions attributed to gibberellins have been traditionally restricted to the regulation of plant stature, seed germination, and flowering. Nonetheless, research in the last years has shown that these functions extend to many other relevant processes. In this review, the current knowledge on gibberellins homeostasis and mode of action is briefly outlined, while specific attention is focused on the many different responses in which gibberellins take part. Thus, those genes and proteins identified as being involved in the regulation of gibberellin responses in model and non-model species are highlighted. The present review aims to provide a comprehensive picture of the state-of-the-art perception of gibberellins molecular biology and its effects on plant development. This picture might be helpful to enhance our current understanding of gibberellins biology and provide the know-how for the development of more accurate research and breeding programs.

RNA Extraction from Plant Tissue with Homemade Acid Guanidinium Thiocyanate Phenol Chloroform (AGPC)

Gene expression studies are a powerful technique to study biological processes, and isolating RNA that is pure, intact, and in sufficient amounts for downstream applications is key. Over the years, the field has moved to the use of commercial kits and ready-made extraction buffers for RNA isolation. This became particularly problematic during the COVID-19 crisis when supply chains were affected and when RNA extraction and analysis reagents were suddenly scarce at a time when they were particularly required. Acid guanidinium thiocyanate-phenol-chloroform (AGPC) is one of the oldest RNA extraction solutions, in use since 1987. It is known as a ready-made solution, sold under different brand names, and is typically the most expensive reagent in the RNA extraction process. In this article, we describe how to prepare a low-cost homemade AGPC solution and provide tips on how to use it for obtaining high-quality RNA, as well as describe possible modifications for different conditions. The protocol is based on a phase separation, where RNA is maintained in the aqueous phase and DNA and proteins remain in the interphase and organic phase. After cleaning, precipitation, and resuspension steps, the RNA is ready to be quantified and used for downstream applications. By following this protocol, good yields of high-quality RNA can be obtained from a wide variety of tissues and organisms, and we exemplify the approach here using plant tissues. Some plant tissues contain extra interferents (such as sugars), and for high-quality RNA isolation from those tissues, an alternate protocol is provided. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: RNA isolation with homemade acid guanidinium thiocyanate-phenol-chloroform (AGPC) Alternate Protocol: RNA isolation from high carbohydrate-containing tissues using an NTES-AGPC combination.

Table Grapes during Postharvest Storage: A Review of the Mechanisms Implicated in the Beneficial Effects of Treatments Applied for Quality Retention

Table grape is a fruit with increasing interest due to its attributes and nutritional compounds. During recent years, new cultivars such as those without seeds and with new flavors have reached countries around the world. For this reason, postharvest treatments that retain fruit quality need to be improved. However, little is known to date about the biochemical and molecular mechanisms related with observed quality improvements. This review aims to examine existing literature on the different mechanisms. Special attention will be placed on molecular mechanisms which activate and regulate the different postharvest treatments applied in order to improve table grape quality.

The Molecular Regulation of Carbon Sink Strength in Grapevine (Vitis vinifera L.)

Sink organs, the net receivers of resources from source tissues, provide food and energy for humans. Crops yield and quality are improved by increased sink strength and source activity, which are affected by many factors, including sugars and hormones. With the growing global population, it is necessary to increase photosynthesis into crop biomass and yield on a per plant basis by enhancing sink strength. Sugar translocation and accumulation are the major determinants of sink strength, so understanding molecular mechanisms and sugar allocation regulation are conducive to develop biotechnology to enhance sink strength. Grapevine (Vitis vinifera L.) is an excellent model to study the sink strength mechanism and regulation for perennial fruit crops, which export sucrose from leaves and accumulates high concentrations of hexoses in the vacuoles of fruit mesocarp cells. Here recent advances of this topic in grape are updated and discussed, including the molecular biology of sink strength, including sugar transportation and accumulation, the genes involved in sugar mobilization and their regulation of sugar and other regulators, and the effects of hormones on sink size and sink activity. Finally, a molecular basis model of the regulation of sugar accumulation in the grape is proposed.