Plant Growth Regulation最新文献

Caffeic acid O-methyltransferase (COMT) catalyzes key steps in the biosynthesis of lignin. It can also act as an N-acetylserotonin O-methyltransferase (ASMT), which participates in the last step of melatonin biosynthesis. Melatonin has been demonstrated to play vital roles in the regulation of plant processes and stress responses. However, the ASMT activity of COMT has not yet been characterized in the non-model plant golden spider lily (Lycoris aurea [L’Hér.] Herb), which is an ornamental that is medicinally important. A previous transcriptome analysis identified the COMT gene (LaCOMT) in this plant. The recombinant LaCOMT protein from E. coli was highly active toward ASMT, and this activity was significantly inhibited by caffeic acid in a dose-dependent manner. LaCOMT-GFP was localized to the cytoplasm and nucleus. Considering that the bulbs of L. aurea can tolerate extreme environmental conditions, such as drought stress, waterlogging and poor soil conditions, the pattern of expression of LaCOMT in different tissues and after exposure to mercuric chloride (HgCl₂) was analyzed. The results revealed that LaCOMT is ubiquitously expressed in all the tissues studied and can be induced by HgCl₂. Moreover, the heterologous overexpression of LaCOMT led to mercury tolerance in transgenic Arabidopsis thaliana plants. This could be attributed to the accumulation of scavenged reactive oxygen species (ROS) by elevating antioxidant enzymes and augmenting antioxidants in the transgenic A. thaliana plants that overexpressed LaCOMT. Our results suggest that LaCOMT participates in the alleviation of Hg toxicity by modulating ROS homeostasis in plants.

Abstract

Flavonoids are secondary metabolites found in plants that possess antioxidant properties. MicroRNAs are small non-coding RNAs that play a crucial role in regulating gene expression and are involved in both developmental and metabolic pathways. The study analysed the differences in indices of lettuce with different leaf colours, a STTM-miR858 silencing vector was constructed using molecular biology techniques, and genetically modified lettuce plants with reduced expression of Las-miR858 were obtained. The interaction mechanism between miR858 and MYB111 was predicted and verified. The study found that reduced expression of miR858 regulated its target MYB111, which subsequently stimulated the expression of key enzyme genes in the flavonoid biosynthesis pathway. This resulted in the accumulation of flavonoids in lettuce, enhancing its antioxidant capacity. This study is the first to explain the regulation of flavonoids by the LasmiR858 network, providing a theoretical and empirical basis and genetic resources for the study of lettuce flavonoid mechanisms.

Abstract

Cadmium (Cd) is a heavy metal that poses harm to both plants and humans. OsHMA3, a member of the heavy metal ATPase (HMA) family, plays a crucial role in sequestering Cd into the vacuoles of roots, thereby limiting its accumulation in rice grains. However, the response of rice plants to Cd under complete loss-of-function of OsHMA3 remains unclear. In this study, we successfully generated OsHMA3 null mutants in an indica variety 93 − 11 using CRISPR/Cas9 technology. A Cd resistance experiment revealed that the Oshma3 mutants exhibited increased sensitivity to Cd compared to the wild-type at a tested concentration of 10 µM CdCl₂. Furthermore, the seedlings of Oshma3 mutant lines displayed inhibited plant growth in the presence of 1 µM Cd, specifically suppressing aboveground growth. As expected, knockout lines of OsHMA3 showed lower Cd accumulation in roots but higher concentrations in shoots compared to wild-type plants, highlighting the role of OsHMA3 in root-to-shoot Cd translocation. We further performed RNA sequencing analysis on wild-type and Oshma3 plants under control and Cd treatment conditions and found that differentially expressed genes were mainly enriched in metal ion binding, integral component of the membranes, and biosynthesis pathways for secondary metabolites triggered by exposure to Cd. When grown in a paddy field, the Oshma3 mutants exhibited shorter plant height, lower seed setting rate, and higher Cd accumulation in grains compared to wild-type plants. Our results indicate that knockout of OsHMA3 in the 93 − 11 variety increases sensitivity to Cd and inhibits plant growth.

A diverse genetic background is essential for genetic analysis and functional genomics research in model plants. In this study, four novel xiaomi-like mutants in different genetic backgrounds, named xiaomi3, xiaomi4, xiaomi5, and xiaomi6, were identified and characterized. These mutants exhibited an extremely early heading phenotype, with heading occurring around 30–40 days after sowing under natural long-day conditions. Significant reductions in plant height, leaf length, leaf width, panicle length, and panicle diameter were observed in the mutants compared to their corresponding wild-types. Notably, these mutants displayed diverse panicle architectures and hull colors, effectively preventing seed mixing between them. Subsequent investigation under controlled short-day and long-day conditions confirmed the significant early heading phenotype of these mutants. Molecular characterization revealed that mutations in the Phytochrome C (SiPHYC) gene, including transposon insertions and a frame shift mutation, were responsible for the extremely early heading phenotype. RNA-sequencing (RNA-Seq) analysis identified 19 differentially expressed genes associated with this phenotype. Additionally, genome-wide InDels and SNPs were identified, providing valuable resources for marker-assisted breeding and genetic studies. These findings will contribute to our understanding of the genetic and molecular mechanisms underlying SiPHYC-mediated photoperiod flowering, and provide valuable resources that will push xiaomi as a C₄ model plant.

Since many cultivated plants, including rice, are susceptible to stress and salt stress, resulting in a tremendous reduction in yield, threatens food security worldwide. Strategies such as using biostimulants to ameliorate salt stress can reduce stress effects and sustain production. The effects of soaking Koshihikari (salt-sensitive) seeds in astaxanthin (AS) under salt stress were determined in the present study. In particular, the seeds of the rice cultivar were subjected to control, salt stress (50 mM NaCl), AS (50 µM), and AS + salt stress treatments for two weeks in hydroponic culture. Thereafter, the plants were harvested, and their growth, physiological, and molecular parameters were analyzed. The results showed that the growth of plants under salt stress was significantly reduced; however, the growth was restored to levels comparable to those of non-stressed plants treated with AS. Salt stress significantly increased the concentrations of malondialdehyde, hydrogen peroxide, and the electrolyte leakage ratio in untreated plants and significantly decreased their concentration in AS-treated plants under the same conditions, with corresponding increases in leaf catalase, peroxidase, and ascorbate peroxidase activities. Leaf Na⁺ concentration markedly increased under salt stress in non-treated plants, and AS treatment reduced the concentration. However, the difference was not statistically significant, which resulted in a significant decrease in the Na⁺/K⁺ ratio in AS-treated plants compared to that in non-treated plants. Salt stress and AS treatment did not alter the concentration of photosynthetic pigments but enhanced the expression of OsBHY, OsNHX1, OsSOS1, and OsHKT1;5 genes. Overall, soaking seeds in AS induced salt stress tolerance in the Koshihikari rice cultivar by reducing oxidative stress damage and enhancing shoot Na⁺/K⁺ balance. Therefore, seed-soaking methods using AS could serve as a good strategy for improving the cultivation of salt-sensitive rice cultivars in saline soils.

Mitochondrial complex I is an NADH-ubiquinone oxidoreductase responsible for 40% of the production of mitochondrial ATP. It contains 14 core subunits and 25–35 non-core ones in different organisms. However, the role of these subunits in plant development remains largely unknown. Here, we report a novel Arabidopsis T-DNA insertion mutant. The T-DNA insertion mutant produced smaller and more serrated leaves than wild-type control. So, it is named that the Arabidopsis small and serrated leaves 1 (ssl1). We identified a T-DNA insertion in the AtMWFE locus- that disrupted the function of AtMWFE in ssl1. AtMWFE encodes a conserved non-core subunit of mitochondrial complex I. The expression of AtMWFE complemented the leaf developmental defects of ssl1- thus SSL1 is the AtMWFE subunit of mitochondrial complex I. We also showed that the compromise of SSL1/AtMWFE function led to the accumulation of ROS. Our findings reveal that SSL1/AtMWFE is required for the function of mitochondrial complex I and the proper ROS level in leaves, and demonstrate that SSL1/AtMWFE plays a critical role in leaf development.

Asymmetric gene expression in a polyploid plant refers to the differential expression of the homeologs of a gene. Bread wheat (Triticum aestivum) with three subgenomes, A, B, and D, is a hexaploid crop with six copies of each chromosome (6n, n = 7). This complexity can result in unequal expression of genes from each parental genome, leading to asymmetry in gene expression. In other polyploid crops like cotton, transcription factors (TF) exhibit genome-biased expression; however, there are no comparable studies for bread wheat. One of plants' most prominent TF gene families is the basic Leucine Zippers (bZIP), which are eukaryote-specific proteins and regulate various biological processes, including stress-related responses. bZIP proteins are dimeric and several heptads long. They exhibit typical coiled-coil structures with strategically placed amino acids in each heptad, responsible for their stability and specificity. Here, we aim to decipher the structural basis of the asymmetric expression of the bZIP TFs in wheat under low and high-temperature conditions. Furthermore, 19 highly expressed stress-related TabZIP TFs were analysed for their asymmetric expression profiles as plants were exposed to temperature-stress conditions. Two benchmarks were used to examine the bZIPs asymmetric gene expression, i.e., (a) the promoter's occupancy by the epigenetic marker histones, namely, H3K4me3 and H3k9ac (both active) and H3K27me3 (repressive), (b) density and diversity of cis-regulatory elements in the promoters. Notably, the genetic basis of the differences in protein sequences of bZIP triads was explored, which may impart structural stability to a specific homeolog, enabling the plant to endure the stress conditions.

Melatonin (MT) regulates and enhances crop tolerance to drought stress. However, the effect of melatonin spraying on grain quality under drought–rehydration treatment is currently insufficiently evaluated. Here, the present study was conducted by spraying 100 μM MT before wheat grain filling and then drought–rehydration treatment was carried out. Rewatering after drought stress increased the appreciably wet gluten content, sedimentation index, total protein content, and gluten content of wheat grains and decreased the prolainm content, albumin content, and globulin content. And MT application effectively alleviated grain quality damage, reducing wet gluten content and gluten content. In addition, MT compensated for the oxidative damage and the membrane lipid peroxidation damage caused by drought–rehydration treatment. In addition, two drought stresses significantly reduced photosynthetic parameters. And MT effectively improved the photosynthetic efficiency. These results indicated that MT is feasible for enhancing wheat resistance and ameliorating grain quality during drought and rehydration.

Salt and alkali stress are considered major abiotic stresses in agriculture. Tea plant (Camellia sinensis), an acidophilic economic crop, is seriously affected by salt and alkali stress, which severely restricts its widespread planting. However, the mechanisms underlying the response of tea plants to salt and alkali stress remain unclear. To understand the physiological and molecular responses of tea plants to salt and alkali stress, tea plants were treated with NaCl and NaHCO₃ to study the effects of salt and alkali stresses, respectively. Tea plants exhibited different symptoms under the NaCl and NaHCO₃ treatments. The leaves of tea plants suffered varying degrees of damage, and concentrations of the quality components epigallocatechin gallate, caffeine, and theanine in the leaves decreased significantly under the NaCl treatment. However, after NaHCO₃ treatment, epigallocatechin and theanine levels were significantly reduced. Photosynthesis and antioxidant enzymes changed significantly to varying degrees under both the NaCl and NaHCO₃ treatments. The stomata closed under both NaCl and NaHCO₃ treatments. After the transcriptome analysis of tea samples treated for one, three, and 7 days with NaCl or NaHCO₃, a large number of differentially expressed genes related to photosynthesis and the antioxidant system were identified. Analysis of the promoters of key differentially expressed genes revealed many light-responsive, hormone-responsive, and stress-responsive elements, and many corresponding upstream transcription factors were also differentially expressed. These results provide a basis for understanding the physiological and molecular responses of tea plants to salt and alkali stress.

The mangrove ecosystems are characterised by high salinity and hypoxia. When viviparous mangrove propagules detach from the mother plants and find a substratum, their roots must respond appropriately to the external environment. Therefore, for an improved understanding of the dynamics of mangrove adaptations to fluctuating intertidal habitats, root transcriptomic and anatomical responses of the germinated propagules of Rhizophora mucronata Lam. and Kandelia candel Druce were analysed. Both species had larger cortexes with aerenchyma spaces, and root cortical/stelar area decreased above five parts per thousand (ppt) of salinity treatment after 60 days. The percentage of suberised endodermal cells in R. mucronata was above 80%, while it increased in K. candel after 60 days of treatment. De novo transcriptome sequencing of K. candel and R. mucronata at 45 and 60 days after salinity treatments identified 766,040 and 558,190 transcripts with predicted open reading frames, respectively, and differential gene expression analysis unveiled ~ 16,000 salt-responsive transcripts. Gene ontology analysis showed enrichment of transcripts related to cell wall biosynthesis (cellulose synthase, expansins), membrane transporters (aquaporins, salt overly sensitive 1, vacuolar ATPase), and hormone signal transduction (delay of germination 1 domain-containing protein, auxin-responsive protein). Interestingly, the differentially expressed solute transporter protein transcripts were higher in K. candel than in R. mucronata. Pathway enrichment analysis revealed the significant expression of flavonoid/flavonol and taurine/hypotaurine biosynthesis pathways, indicating the role of specialised metabolites in stress response. A total of 10 differentially expressed transcripts were validated using qRT-PCR, and a positive correlation of 0.62 (K. candel) and 0.68 (R. mucronata) was observed between the RNA sequencing data and qRT-PCR. Overall, this study contributes to understanding mangrove ecological adaptations and stress response mechanisms to salinity stress in the early developing propagules.