Planta最新文献

Ginsenosides R2 and F2 are key active components of Panax japonicus var. major which exhibit a wide range of pharmacological effects. However, few UDP-glycosyltransferases (UGTs) involved in Rh2 and F2 biosynthesis have been identified. In this study, 12 UGTs from Panax japonicus var. major were predicted and characterized. Among them, one UGT (PjvmUGT45) exhibited superior catalytic activities by catalyzing the C3 hydroxyl glycosylation of protopanaxadiol (PPD) and compound K to form Rh2 and F2, respectively. Especially, PjvmUGT45 showed certain substrate specificity and regional specificity at the C-3 sites of PPD-type ginsenosides. Site-directed mutagenesis showed that Gln334, His349, Ser354, and Asp373 were key residues for PjvmUGT45, and the K280A mutant highly improved its activity. Our results revealed the biosynthetic mechanism of ginsenosides in Panax japonicus var. major, providing a novel alternative UGT for ginsenoside Rh2 production by synthetic biological methods.

Main conclusion: Under salt stress, autophagy regulates ionic balance, scavenges ROS, and supports nutrient remobilization, thereby alleviating osmotic and oxidative damage. Salt stress is a major environmental challenge that significantly impacts plant growth and agricultural productivity by disrupting nutrient balance, inducing osmotic stress, and causing the accumulation of toxic ions like Na⁺. Autophagy, a key cellular degradation and recycling pathway, plays a critical role in enhancing plant salt tolerance by maintaining cellular homeostasis and mitigating stress-induced damage. While autophagy has traditionally been viewed as a response to nutrient starvation, recent research has highlighted its importance under various environmental stresses, particularly salt stress. Under such conditions, plants activate autophagy through distinct signaling pathways involving autophagy-related genes (ATGs), Target of Rapamycin (TOR) proteins, and reactive oxygen species (ROS). Salt stress induces the expression of ATG genes and promotes the formation of autophagosomes, which facilitate the degradation of damaged organelles, denatured proteins, and the sequestration of Na⁺ into vacuoles, thereby improving stress tolerance. Recent studies have also suggested that autophagy may play a direct role in salt stress signaling, linking it to the regulation of metabolic processes. This review discusses the molecular mechanisms underlying autophagy induction in plants under salt stress, including the roles of ATGs and TOR, as well as the physiological significance of autophagy in mitigating oxidative damage, maintaining ion balance, and enhancing overall salt tolerance. In addition, we discussed the metabolic changes related to autophagy in stressed plants and examined the broader implications for managing plant stress and improving crops.

Main conclusion: Optimizing environmental factors can significantly increase the growth and secondary metabolite synthesis of hydroponically grown medicinal plants. This approach can help increase the quality and quantity of pharmacologically important metabolites to enhance therapeutic needs. Medicinal plants are key therapeutic sources for treating various ailments. The increasing demand for medicinal plants has resulted in the overharvesting of these plants in their natural habitat, which can lead to their extinction in the future. Soil-based cultivation faces challenges, such as a lack of arable land, drastic climatic changes, and attacks by soil-borne pathogens. To overcome these challenges, hydroponic cultivation, known as soilless cultivation, is a sustainable method. The yield and quality of medicinal plants depend on environmental factors, such as nutrients, pH, electrical conductivity, temperature, light, nanoparticles, phytohormones, and microorganisms. This article explores the impact of these environmental factors on the growth and secondary metabolite content of hydroponically grown medicinal plants. Our review reveals how environmental factors qualitatively and quantitatively influence the growth and secondary metabolites of medicinal plants grown in hydroponic systems and how these factors can be integrated into the enhancement of therapeutic compounds.

Main conclusion: Sorghum kernel composition is a crucial characteristic that determines its functional qualities. The total protein content of sorghum grain increases under drought stress, but starch, protein digestibility, and micronutrient contents decrease. Sorghum (Sorghum bicolor L.) is a staple source of starch, protein, and micronutrients in Ethiopia, where it is a key ingredient in local foods like injera and traditional beverages such as tela and areke. It has adapted remarkably to the diverse climatic conditions and soils of both highland and lowland regions. However, grain quality is influenced by climate change, drought stress, and genotype-environment interactions. Under drought conditions, sorghum shows reduced starch content, protein digestibility, and micronutrient levels, as well as increased kernel hardness and total protein content. The genetic and geographic diversity of sorghum makes it an adaptable crop, essential for breeding and diversity studies. Genome-wide association studies (GWAS) have emerged as essential tools for identifying candidate genes linked to key traits, thereby advancing genetic improvement initiatives, particularly for Ethiopian sorghum landraces. Advances in genotyping techniques, particularly genotyping-by-sequencing (GBS) and association mapping, have facilitated the identification of quantitative trait loci (QTL) associated with grain quality, enhancing breeding efficiency and the development of resilient, high-quality sorghum varieties. This review explored the genetic and phenotypic diversity of sorghum, focusing on grain quality traits, molecular mechanisms, and responses to drought stress.

Main conclusion: A gene within a single subclade of NCED genes is triggered in response to both, short- and long-term dehydration treatments, in three model dicot species. During dehydration, some plants can rapidly synthesise the stress hormone abscisic acid (ABA) in leaves within 20 min, triggering the closure of stomata and limiting further water loss. This response is associated with significant transcriptional upregulation of Nine-cis-Epoxycarotenoid Dioxygenase (NCED) genes, which encode the enzyme considered to be rate-limiting in ABA biosynthesis. However, most embryophyte species possess multiple NCED genes, and it is not currently known whether there is any phylogenetic pattern to which NCED genes are involved in this response. We tested transcriptional responses to dehydration for all NCED genes present in three diverse eudicot species-Arabidopsis thaliana (Arabidopsis), pea and tomato-over both the timeframe of stomatal responses (< 20 min) and in response to sustained dehydration (hours). We found that there is a single NCED gene per species, AtNCED3, PsNCED2, and SlNCED1, respectively, that is rapidly upregulated by dehydration. Using a null mutant, we confirmed that the rapidly responsive gene identified in Arabidopsis is important for physiological responses to a sudden drop in humidity. Analysis of the relationships and the evolutionary history of NCED genes using available sequence data from diverse land plant species revealed that the identified genes in each species all belong to the same subclade within the gene family, suggesting a conserved role for this subclade in rapid dehydration responses in eudicots. These findings enable future phylogenetically-informed prediction of genes of interest for rapid dehydration responses within this important multigene family in eudicot species.

Main conclusion: The starch-statolith theory was established science for a century when the existence of gravitropic, starchless mutants questioned its premise. However, detailed kinetic studies support a statolith-based mechanism for graviperception. Gravitropism is the directed growth of plants in response to gravity, and the starch-statolith hypothesis has had a consensus among scientists as the accepted model for gravity perception. However, in the late 1980s, with the isolation of a starchless mutant (lacking phosphoglucomutase, pgm) of Arabidopsis thaliana that was gravitropic, a statolith-based hypothesis for graviperception was questioned. Two groups studied the physiology and gravitropism kinetics of this pgm mutant, and these papers were published side-by-side in Planta. Based on the observation that the starchless mutant was responsive to gravity, Tim Caspar and colleagues (Caspar and Pickard, Planta 177:185-197, 1989) suggested that their results negated the starch-statolith hypothesis. In contrast, John Z. Kiss (Kiss et al., Planta 177:198-206, 1989) and colleagues turned the argument around 180 degrees and concluded that since a full complement of starch is required for full gravitropic sensitivity, in fact, their pgm studies provided strong support for a statolith-based model for gravity perception. Kiss and coworkers also provided evidence that the starchless plastids were relatively dense and proposed that these organelles function as statoliths in the pgm mutant plants. These two publications stimulated novel approaches (e.g., magnetophoresis, optical tweezers, spaceflight experiments, and laser ablation) to the study of gravity perception in plants. The controversy regarding the starch-statolith hypothesis remained for about a decade or so, but the current consensus supports a statolith-based model for graviperception in plants.

Main conclusion: This article offers a comprehensive overview of the starch, protein, oil, and carotenoids content in maize kernels, while also outlining future directions for research in this area. Maize is one of the most important cereal crops globally. Maize kernels serve as a vital source of feed and food, and their nutritional quality directly impacts the dietary intake of both animals and humans. Maize kernels contain starch, protein, oil, carotenoids, and a variety of vitamins and minerals, all of which are important for maintaining life and promoting health. This review presents the current understanding of the content of starch, protein, amino acids, oil, and carotenoids in maize kernels, while also highlighting knowledge gaps that need to be addressed.

Main conclusion: The exogenous application of RNAi technology offers new promises for crops improvement. Cell-based or synthetically produced strands are economical, non-transgenic and could induce the same responses. The substantial population growth demands novel strategies to produce crops without further damaging the environment. RNA interference mechanism is one of the promising technologies to biologically control pests and pathogens in crops, suppressing them by cancelling protein synthesis related to parasitism/pathogenesis. The transgenic approach to generate host-induced gene silencing demonstrated high efficacy in controlling pests or pathogens by RNAi mechanism. However, transgenic technology is tightly regulated and still negatively perceived by global consumers. This review presents the basic biology of small RNA, the main actor of the RNAi mechanism, and tested non-transgenic approaches to induce RNAi exogenously. Novel avenues are offered by the discovery of cross-kingdom RNAi, that naturally, plants also deliver small RNA to suppress the growth of their threats. Future applications of non-transgenic RNAi-based biocontrol will involve the production of dsRNA on an industrial scale. Here, the attempts to provide dsRNA for routine application in farms are also discussed, emphasizing that the technology must be accessible by the countries with the greatest population which mostly are poorer ones.

Main conclusion: Phytoglobin1 promotes Arabidopsis somatic embryogenesis through the mediation of ethylene and the ERFVII HRE2. Generation of somatic embryos in Arabidopsis (Arabidopsis thaliana) is a two-step process, encompassing an induction phase where embryogenic tissue (ET) is formed followed by a developmental phase encouraging the growth of the embryos. Using previously characterized transgenic lines dysregulating the class 1 Phytoglobin (Pgb1) we show that suppression of Pgb1 decreases somatic embryogenesis (SE). Both the formation of ET (SE efficiency) and production of SE (SE productivity) are repressed in explants where Pgb1 is downregulated. The levels of Pgb1 transcripts peak in the middle phase of the induction period coinciding with the formation of the ET. Presence of Pgb1 results in a transcriptional depression of ethylene synthesis and of the class VII ethylene transcription factor (ERFVII) HRE2. Suppression of ethylene after day 3 of induction, or repression of HRE2 are needed for SE efficiency and the decline in HRE2 transcripts appears to be independent from the level of ethylene. Over-expression of HRE2 inhibits SE efficiency regardless of the expression of Pgb1. Furthermore, a functional HRE2 generates a peak in Pgb1 transcripts during the middle induction phase. The expression of another ERFVII, RAP2.12, is not altered by changes in Pgb1 levels, and disruption of RAP2.12 has no effect on SE efficiency although it enhances SE productivity in a Pgb1-independent fashion. Thus, Pgb1 is an important regulator of Arabidopsis SE, and its action is linked to changes in ethylene and the ERFVII HRE2.

Main conclusion: This review serves as a critical framework for guiding future research into the causes of russeting and the development of effective control strategies to enhance fruit quality. Russeting is a condition characterized by the formation of brown, corky patches on fruit skin which significantly impairs both the quality and market value of apples. This phenomenon arises from a complex interplay of various biotic and abiotic factors. Among the abiotic factors, environmental conditions, such as light, temperature, and relative humidity, as well as nutrient imbalances and the application of agrochemicals are important, whereas biotic factors include the influence of yeasts, fungi, viruses, and bacteria. The susceptibility of apple cultivars to russeting varies with yellow-fleshed varieties generally exhibiting higher incidences compared to red-fleshed ones. While russeting is partly determined by varietal and genetic factors, it can be mitigated through the implementation of effective cultural practices, nutrient management, plant growth regulators, biological agents, and pesticides. Understanding these dynamics provides valuable insights for developing future research strategies aimed at improving fruit quality and production.