Journal of Integrative Plant Biology最新文献

Sphingolipids, including ceramides, are structural membrane lipids that function in membrane trafficking and cell polarity. Very-long-chain (VLC) ceramide synthases are essential for plant growth and development, but how VLC ceramide synthases affect developmental programs and their exact roles in plant growth remain unclear. Here, we report that two VLC ceramide synthases, LONGEVITY ASSURANCE GENE ONE HOMOLOG 1 (LOH1) and LOH3, link sphingolipid metabolism and thermomorphogenesis, that is, plant morphogenesis in response to higher temperatures. We found that high ambient temperature (28°C) induced an increase in plant VLC ceramide contents, and defects in LOH1 or LOH3 function inhibited hypocotyl elongation at this temperature. PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) potentiates the thermal sensitivity of hypocotyl morphogenesis in a LOH1- and LOH3-dependent manner, directly binding to the LOH1 and LOH3 promoters to enhance their expression. Strikingly, LOH1 and LOH3 also enhance PIF4-dependent transcriptional activation of downstream genes, including PIF4 itself, LOH1, and LOH3. Our study reveals a regulatory mechanism in which PIF4 activates the transcription of LOH1 and LOH3; in turn, LOH1 and LOH3 enhance PIF4 signaling by supporting PIF4-mediated transcriptional responses, thereby controlling plant growth in response to temperature.

Numerous members of the Nepeta genus (family Lamiaceae, subfamily Nepetoideae) are medicinal herbs and sources of important bioactive compounds. Most Nepeta species produce iridoids, which are monoterpenoids that deter herbivores and pathogens and are potential biopesticides. In Nepeta, some species produce iridoid aglycones and glycosylated iridoids (referred to as chemotype A), some produce only glycosylated iridoids (chemotype B), and some produce neither iridoid aglycones nor glycosylated iridoids (chemotype C). Here, we show that the observed diversity in iridoids is, at least partially, attributed to evolutionary gains and losses of key biosynthetic genes. Based on reconstructed phylogenetic relationships, we propose a scenario in which partial or complete loss of the ability to synthesize iridoids with specific stereochemistries in the taxa with chemotypes B and C resulted from independent evolutionary events. These observations improve our understanding of metabolic diversity in the Nepeta genus and may inform efforts to produce specific iridoids in plants.

Soil salinization poses a global threat to agricultural productivity by degrading arable land. Preventing the rapid degradation of chlorophyll caused by saline-alkali stress is a crucial means to improve plant resistance and productivity. In this study, RNA sequencing identified CsPPH, a pheophytinase-encoding gene that functions as a negative regulator of both photosynthesis and saline-alkali tolerance in cucumber (Cucumis sativus L.). Saline-alkali stress rapidly induces the expression of related to APETALA2 2.12 (CsRAP2.12). Subsequently, CsRAP2.12 activates the transcription of both ethylene response factor 113-like (CsERF113L) and CsRAP2.7, while CsERF113L further transcriptionally regulates CsRAP2.7. CsERF113L promotes chlorophyll degradation and reactive oxygen species (ROS) accumulation both through direct transcriptional upregulation of CsPPH, chlorophyll b reductase (CsNYC1), and chlorophyllase 2 (CsCLH2) and by indirectly stimulating ethylene synthesis via upregulation of 1-aminocyclopropane-1-carboxylic acid synthase 6/9/10 (CsACS6/9/10), thereby impairing photosynthesis and accelerating senescence. CsRAP2.7 indirectly promotes saline-alkali stress-induced chlorophyll degradation and photosynthetic inhibition by facilitating CsERF113L-mediated transcriptional activation of CsPPH, CsCLH2, and CsACS6/9/10. Therefore, knockout of either CsRAP2.12, CsERF113L, or CsRAP2.7 significantly alleviated chlorophyll degradation and enhanced photosynthetic performance under saline-alkali stress, ultimately improving antioxidant capacity and stress tolerance. These findings reveal that the CsRAP2.12-CsERF113L/CsRAP2.7 module promotes saline-alkali stress-induced chlorophyll degradation and photosynthetic inhibition via a dual regulatory mechanism. Genetic disruption of this module significantly improves cucumber tolerance to saline-alkali stress.

Plants, as sessile organisms, continuously encounter challenges posed by fluctuating environmental conditions. To adapt to these stresses, they have developed dynamic regulatory mechanisms, including post-translational modifications (PTMs) such as SUMOylation. Small ubiquitin-like modifier (SUMO) proteins are covalently attached to target proteins, resulting in alterations to their stability, localization, activity, and interactions. Over the past two decades, SUMOylation has emerged as a critical regulator of responses to various abiotic and biotic stresses in plants. This review summarizes recent advancements in the roles of SUMOylation in response to temperature stress, drought conditions, salinity stress, and pathogen attacks. Furthermore, we discuss the mechanism by which SUMOylation functions as an essential molecular switch that balances developmental processes and stress responses, and provide a perspective on future investigations in this field. By integrating current knowledge with future perspectives, this summary and perspective will deepen our understanding of the roles of PTMs in plant stress responses and offer insights for improving crop yields and resistance.

Somatic embryogenesis (SE) enables somatic cells to develop directly into embryos. SE is a major approach of regeneration, but recalcitrance to SE has become one of the main obstacles to biotechnology-aided breeding, especially for perennial woody plants. Citrus is one of the most important fruit crops in the world, and glycerol has long been used to induce SE from the embryogenic callus (EC) of citrus. Recently, we reported that CsIAA4-mediated repression of auxin signaling plays a critical role in glycerol-induced citrus SE, but the downstream signaling cascade remains to be elucidated. In this study, the HD-Zip transcription factor CsHAT14 was identified as a key downstream regulator of auxin signaling in citrus SE. CsARF5 directly promoted CsHAT14 expression, which repressed SE through suppression of critical regeneration-related genes (CsDOF3.4 and CsWOX13) and the auxin efflux gene CsPILS5. CsIAA4 interacted with CsARF5, and this interaction attenuated CsARF5-mediated transcriptional activation of CsHAT14, thereby de-repressed CsHAT14- directly suppressed genes including CsDOF3.4, and thus promoted SE. Knockdown of CsDOF3.4 resulted in downregulation of cell cycle-related genes and impaired SE. Our findings established the CsIAA4-CsARF5 and CsHAT14-CsDOF3.4 modules-mediated auxin signaling cascade that coordinates citrus SE, which advanced our understanding of the mechanisms underlying SE and supported improvement of regeneration efficiency in citrus biotechnology applications.

Anthocyanins are a critical component influencing the quality of grape. At varying concentrations, methyl jasmonate (MeJA) shows a concentration-dependent effect on the anthocyanin content in grapes. However, its molecular mechanism is unclear. In this study, we characterized an E3 ubiquitin ligase VvPUB8 that responds to MeJA and verified its negative regulation of grape anthocyanin synthesis through overexpression and mutant vectors' transformation of "Gamay" calli. Furthermore, VvPUB8 interacted directly with the transcription factor VvbHLH93, which can positively regulated anthocyanin synthesis by activating the promoters of VvMYB15 and VvMYB5a. The stability or activity of proteins regulated by ubiquitination largely depends on the type and number of the attached ubiquitin. Here, we showed that VvPUB8 facilitated K6- and K33-linked ubiquitination of VvbHLH93, thereby promoting VvbHLH93 degradation. Exogenous MeJA accelerated VvbHLH93 protein degradation and inhibited VvMYB15 promoter activation. Consequently, the synthesis of grape anthocyanins was suppressed. This study revealed that in response MeJA, VvPUB8 regulates VvbHLH93 stability through conjugation of distinct polyubiquitin chains, thereby modulating VvMYB15 and VvMYB5a promoter activity, thus inhibiting anthocyanin synthesis.

Medicinal plants produce important pharmaceuticals, but these compounds are often present at low levels or only in specific tissues; in addition, many medicinal plants produce small amounts of biomass and are difficult to cultivate. Genome editing for agronomic traits and metabolic engineering holds promise for improving pharmaceutical production, and genome-editing applications in medicinal plants have expanded as genome-editing techniques have advanced. For example, genome editing has been used to regulate the production of phenolic acids and tanshinone metabolites of Salvia miltiorrhiza in medicinal plants. In this review, we synthesize the current knowledge on the development and applications of gene-editing tools in medicinal plants. Furthermore, we summarize the limitations of genome editing in these species and propose solutions for addressing these challenges to fully harness this technology for improving these important plants. We focus on novel technologies to enhance the regeneration rates of transgenic plants, artificial intelligence-assisted multiomics approaches for predicting editing efficiency, key components that optimize genome-editing efficacy, and the development of innovative gene-editing systems. Finally, we offer perspectives on advancing metabolic engineering strategies for medicinal plants.

Soybean is a vital source of vegetable oil, protein, feed, and industrial raw materials, yet its yield remains considerably lower than that of major cereal crops. Unlike rice and wheat, which rely heavily on nitrogen fertilizers to promote tillering and enhance productivity, soybean acquires over 70% of its nitrogen through symbiotic nitrogen fixation. Tang et al. (pages 75–95) report that knockout of the gibberellin receptor gene GmGID1-2 boosts both soybean yield and nitrogen fixation—a dual benefit not observed in the semi-dwarf mutants of cereals. The cover image illustrates a GmGID1-2 knockout soybean plant (right) that, despite its shorter stature, exhibits increased branching, more pods and seeds, and ultimately higher yield compared to the wild type (left), alongside a root system with more nodules and greater capacity to fix nitrogen. The pleiotropic benefits of GmGID1-2 knockout alleles suggest a promising strategy for advancing sustainable soybean agriculture.