Recent Advances in Studying the Regulation of Fruit Ripening in Tomato Using Genetic Engineering Approaches

SlNAC12, a novel NAC-type transcription factor, confers salt stress tolerance in tomato

KEY MESSAGE

SlNAC12 enhances salt stress tolerance of transgenic tomato by regulating ion homeostasis, antioxidant activity and flavonoids biosynthesis Soil salinization is a major environmental factor that adversely affects plant growth and development. NAC (NAM, ATAF1/2, and CUC2) is a large family of plant-specific transcription factors that play crucial roles in stress response. Here, we investigated the role of a novel NAC transcription factor, SlNAC12, in conferring salt stress tolerance in tomato (Solanum lycopersicum). Subcellular localization and yeast assays studies revealed that SlNAC12 is localized in the nucleus with weak transcriptional activity. SlNAC12 transcript was induced by salt stress in the leaves and roots of tomato seedlings. Overexpression of SlNAC12 in tomato led to significantly reduced plant height and root length. Transgenic tomato lines overexpressing of SlNAC12 (OE#1 and OE#3) exhibited enhanced tolerance to salinity, as evidenced by reduced the inhibitory effect of growth parameters under salt stress compared to wild type (WT). Overexpression of SlNAC12 in tomato affected Na+ and K+ homeostasis, leading to reduced Na+/K+ ratio, enhanced activity of antioxidant enzymes and decreased reactive oxygen species (ROS) accumulation under salt stress. Furthermore, the transcript levels of several genes involved in flavonoids metabolism and the levels of flavonoids accumulation were increased in SlNAC12-overexpressing tomato lines. Collectively, this study suggests that SlNAC12 transcription factor enhances salt stress tolerance in tomato is correlated with ion homeostasis, antioxidant enzyme systems, and flavonoids accumulation.

Cullin-Conciliated Regulation of Plant Immune Responses: Implications for Sustainable Crop Protection

Cullins are crucial components of the ubiquitin-proteasome system, playing pivotal roles in the regulation of protein metabolism. This review provides insight into the wide-ranging functions of cullins, particularly focusing on their impact on plant growth, development, and environmental stress responses. By modulating cullin-mediated protein mechanisms, researchers can fine-tune hormone-signaling networks to improve various agronomic traits, including plant architecture, flowering time, fruit development, and nutrient uptake. Furthermore, the targeted manipulation of cullins that are involved in hormone-signaling pathways, e.g., cytokinin, auxin, gibberellin, abscisic acids, and ethylene, can boost crop growth and development while increasing yield and enhancing stress tolerance. Furthermore, cullins also play important roles in plant defense mechanisms through regulating the defense-associated protein metabolism, thus boosting resistance to pathogens and pests. Additionally, this review highlights the potential of integrating cullin-based strategies with advanced biological tools, such as CRISPR/Cas9-mediated genome editing, genetic engineering, marker-associated selections, gene overexpression, and gene knockout, to achieve precise modifications for crop improvement and sustainable agriculture, with the promise of creating resilient, high-yielding, and environmentally friendly crop varieties.

Virus-Induced galactinol-sucrose galactosyltransferase 2 Silencing Delays Tomato Fruit Ripening

Tomato fruit ripening is an elaborate genetic trait correlating with significant changes at physiological and biochemical levels. Sugar metabolism plays an important role in this highly orchestrated process and ultimately determines the quality and nutritional value of fruit. However, the mode of molecular regulation is not well understood. Galactinoal-sucrose galactosyltransferase (GSGT), a key enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs), can transfer the galactose unit from 1-α-D-galactosyl-myo-inositol to sucrose and yield raffinose, or catalyze the reverse reaction. In the present study, the expression of SlGSGT2 was decreased by Potato Virus X (PVX)-mediated gene silencing, which led to an unripe phenotype in tomato fruit. The physiological and biochemical changes induced by SlGSGT2 silencing suggested that the process of fruit ripening was delayed as well. SlGSGT2 silencing also led to significant changes in gene expression levels associated with ethylene production, pigment accumulation, and ripening-associated transcription factors (TFs). In addition, the interaction between SlGSGT2 and SlSPL-CNR indicated a possible regulatory mechanism via ripening-related TFs. These findings would contribute to illustrating the biological functions of GSGT2 in tomato fruit ripening and quality forming.

New Advances in the Study of Regulation of Tomato Flowering-Related Genes Using Biotechnological Approaches

The tomato is a convenient object for studying reproductive processes, which has become a classic. Such complex processes as flowering and fruit setting require an understanding of the fundamental principles of molecular interaction, the structures of genes and proteins, the construction of signaling pathways for transcription regulation, including the synchronous actions of cis-regulatory elements (promoter and enhancer), trans-regulatory elements (transcription factors and regulatory RNAs), and transposable elements and epigenetic regulators (DNA methylation and acetylation, chromatin structure). Here, we discuss the current state of research on tomatoes (2017-2023) devoted to studying the function of genes that regulate flowering and signal regulation systems using genome-editing technologies, RNA interference gene silencing, and gene overexpression, including heterologous expression. Although the central candidate genes for these regulatory components have been identified, a complete picture of their relationship has yet to be formed. Therefore, this review summarizes the latest achievements related to studying the processes of flowering and fruit set. This work attempts to display the gene interaction scheme to better understand the events under consideration.