Plant Direct最新文献

In plants, the primary form of energy stored in seed lipid droplets, triacylglycerol (TAG), is catabolized during germination to support pre-photosynthetic growth. Although this process is essential for seedling development, it is incompletely understood. In a screen for Arabidopsis thaliana mutants displaying delayed degradation of the lipid droplet coat protein oleosin, five independent mutations in PECTIN METHYLESTERASE31 (PME31) were recovered. In addition to delayed oleosin degradation, pme31 mutant seedlings exhibited sustained lipid droplets and elevated levels of several TAG and diacylglycerol species. Although structural prediction classified PME31 as a pectinesterase, this structural family also includes a putative E. coli lipase, YbhC. Moreover, PME31 lacks an N-terminal signal peptide that would target it to the cell wall, where pectin resides. We found that a fluorescent PME31 reporter was cytosolic and partially associated with peroxisomes, the site of fatty acid catabolism, during lipid mobilization. Our findings suggest that, in contrast to canonical PMEs, which modify cell wall pectin, PME31 functions at peroxisomes to directly or indirectly promote lipid mobilization.

Two types of CRISPR/Cas systems (Cas9 and Cas13) have been used to combat eukaryotic viruses successfully. In this study, we established resistance to the DNA virus BSCTV and RNA virus TMV in Nicotiana benthamiana using the CRISPR-Cas12a multiplex gene editing system. We employed two effector proteins LbCas12a and FnCas12a coupled with six guide RNAs targeting virus genome and a novel mRNA-gRNA nucleic acid complex to transport gRNA efficiently. Compared with the BSCTV accumulation in the wild-type N. benthamiana, it was reduced by more than 90% by most transgenic events derived at 7 days post-inoculation. Additionally, the shoot-tip leaves were normal in the transgenic plants, whereas they appeared severely curled and stunted in wild-type N. benthamiana at 15 days post-infection. Target sites evaluation revealed that the editing system can directly destroy the structure of BSCTV viral genomes via large fragment deletions. We quantified TMV virus accumulation in the transgenic N. benthamiana lines by monitoring dynamic changes in GFP fluorescence and quantitative analysis by qPCR showed that the CRISPR-Cas12a system can introduce TMV virus resistance to N. benthamiana by preventing its systemic spread. Our study provides an innovative strategy-an mRNA-gRNA nucleic acid complex-which has proven to be highly effective in the gene-editing system and offers an efficient antiviral approach for generating virus-resistant plants.

Sugars are important both as an energy source and a signaling cue. In Arabidopsis thaliana, SPINDLY (SPY) is the bona fide O-fucosylation transferase that links sugar with various plant growth and development processes. Previously, spy was shown to display a strong salt and drought tolerance phenotype. Herein we confirmed the phenotype and further studied its mechanism. We found that abscisic acid (ABA) elevated SPY expression in guard cells, and SPY is involved in ABA-induced stomatal closure. We show that SPY regulates the rearrangement of the microtubule cytoskeleton in guard cells. Moreover, ABA-induced microtubule reorganization is enhanced in spy mutants. Mechanistically, SPY interacts with α-tubulin1 (TUA1) in both yeast-two hybrid, bimolecular fluorescence complementation and split luciferase complementation imaging assays, indicating that TUA1 may be O-fucosylated by SPY. Our work is in line with the notion that SPY has many substrates involved in diverse processes in plants, and also unearths a key mechanism how glycosylation regulates the stomata movement via the microtubule cytoskeleton.

Flower formation has been a primary focus in botanical research, leading to the identification of multiple factors regulating flowering over the past 30 years. The MADS transcription factors SEPALLATA3 (SEP3) and APETALA1 (AP1) are essential for floral meristem development and organ identity. In Arabidopsis, SEP3 functions as a central integrator, combining MADS proteins into a tetrameric complex, with its interaction with AP1 playing a key role in sepal and petal formation. This research explores AtSEP3 and AtAP1, with particular emphasis on the Leu residue in the K1 subfunctional domain of AtSEP3, which is necessary for their interaction. A predicted structural model of AP1 was used, followed by protein docking with SEP3, which indicated that Leu residues at positions 115 and 116 are critical binding sites. Mutations at these position were examined through yeast two-hybrid assays and other techniques, identifying Leu 116 as a significant site. Subsequent purification and EMSA analysis revealed that mutations in the leucine zipper of SEP3 decreased its DNA binding ability. Observations of transgenic plants showed that disruption of AtSEP3 and AtAP1 interaction resulted in extended vegetative growth, increased size and number of rosette leaves, and modifications in floral structures. This study offers new insights into the interaction mechanism between AP1 and SEP3 during flowering.

Halophytes, plants that thrive in high-salinity environments, host unique microbial communities, including fungal endophytes, which contribute to plant growth and pathogen resistance. This study aimed to isolate, identify, and evaluate the antagonistic potential of fungal endophytes from the halophytic plant Limonium axillare, collected from both inland and coastal habitats. Fungal endophytes were isolated, identified via molecular techniques, and tested for antagonistic activity against phytopathogenic fungi using dual-culture assays. The results showed a diverse range of fungal endophytes, with Aspergillus and Cladosporium being the dominant genera. A total of 152 endophytic fungi were isolated from both locations, with 95 isolates coming from coastal plants and 57 from inland species. The isolates exhibited varying degrees of antagonistic activity against phytopathogens, highlighting their potential role in plant protection. Further research is needed to clarify these interactions' mechanisms and investigate their practical applications in agriculture. An endophytic isolate of Aspergillus terreus strain ((AL10) lim10qu) (ON210104.1) exhibited potent in vitro antifungal activity against Fusarium oxysporum, a pathogenic fungus affecting tomato plants. Greenhouse experiments demonstrated that the fungus significantly increased both the length of tomato seedlings and the overall plant biomass. Both laboratory-based (in vitro) and field-based (in vivo) evaluations of the strain ((AL10) lim10qu) (A. terreus) against F. oxysporum suggest the promising role of endophytes as effective biological control agents. Analysis using Gas Chromatography-Mass Spectrometry of the fungal extract detected around 100 compounds (secondary metabolites). In addition to gradually reducing the need for chemical fungicides, bio-products can also contribute to sustainable agriculture.

Biotin carboxyl carrier protein (BCCP) is a subunit of the heteromeric acetyl-CoA carboxylase (htACCase), and it chemically links the two half-reactions that constitute the formation of malonyl-CoA from acetyl-CoA, a critical reaction in fatty acid biosynthesis. Because plants are a major source of edible fats and oils, it is important to understand the structural organization of the plant htACCase, relative to its potential to regulate fatty acid biosynthesis in plant plastids. Moreover, unique to the plant htACCase, noncatalytic subunits called biotin attachment domain-containing (BADC) proteins are important in the assembly of the holoenzyme, and they specifically interact with the bcCP and the biotin carboxylase (BC) subunits. We report herein NMR structural studies of the Arabidopsis BCCP isozymes (bcCP1 and BCCP2). We calculated the structure of C-terminal domain of BCCP1 (K₂₀₀-P₂₈₀) and explored structural changes in the BCCP1 protein upon its interactions with bc and BADC. The chemical shift perturbation experiments identified potential surface residues on the BCCP1 protein that may facilitate physical interactions between BC and BADC proteins. These studies indicate that the BADC protein interacts with a "thumb"-like protrusion, which is a common structural feature of the bacterial and plant bcCPs, and thereby acts as a potential "cap" to facilitate the assembly of a BC-BCCP-BADC complex.

Accurate and nondestructive estimation of plant biomass is crucial for optimizing plant productivity, but existing methods are often expensive and require complex experimental setups. To address this challenge, we developed an automated system for estimating plant root and shoot biomass over the plant's lifecycle in hydroponic systems. This system employs a robotic arm and turntable to capture 40 images at equidistant angles around a hydroponically grown lettuce plant. These images are then processed into silhouettes and used in voxel-based volumetric 3D reconstruction to produce detailed 3D models. We utilize a space carving method along with a raytracing-based optical correction technique to create high-accuracy reconstructions. Analysis of these models demonstrates that our system accurately reconstructs the plant root structure and provides precise measurements of root volume, which can be calibrated to indicate biomass.

Tropical milkweed (Asclepias curassavica) serves as a host plant for monarch butterflies (Danaus plexippus) and other insect herbivores that can tolerate the abundant cardiac glycosides that are characteristic of this species. Cardiac glycosides, along with additional specialized metabolites, also contribute to the ethnobotanical uses of A. curassavica. To facilitate further research on milkweed metabolism, we assembled the 197-Mbp genome of a fifth-generation inbred line of A. curassavica into 619 contigs, with an N50 of 10 Mbp. Scaffolding resulted in 98% of the assembly being anchored to 11 chromosomes, which are mostly colinear with the previously assembled common milkweed (A. syriaca) genome. Assembly completeness evaluations showed that 98% of the BUSCO gene set is present in the A. curassavica genome assembly. The transcriptomes of six tissue types (young leaves, mature leaves, stems, flowers, buds, and roots), with and without defense elicitation by methyl jasmonate treatment, showed both tissue-specific gene expression and induced expression of genes that may be involved in cardiac glycoside biosynthesis. Expression of a CYP87A gene, the predicted first gene in the cardiac glycoside biosynthesis pathway, was observed only in the stems and roots and was induced by methyl jasmonate. Together, this genome sequence and transcriptome analysis provide important resources for further investigation of the ecological and medicinal uses of A. curassavica.

In Populus and many other tree species, photoassimilate sucrose diffuses down a concentration gradient via symplastically connected mesophyll cells to minor vein phloem for long-distance transport. There is no evidence for apoplastic phloem-loading in Populus. However, plasma membrane sucrose transporters (SUT1 and SUT3) orthologous to those associated with apoplastic phloem loading are expressed in vascular tissues of poplar. While SUT3 functions in sucrose import into developing xylem, the role of SUT1 remains unclear. Here, we overexpressed PtaSUT1 in Populus tremula x P. alba to examine the effects on sucrose partitioning in transgenic plants. Overall leaf sucrose levels were similar between wild type and transgenic lines. Stem sucrose levels were not changed in bark but were significantly reduced in the adjacent xylem, suggesting hindered intercellular sucrose trafficking from the phloem to the developing xylem. Fully expanded leaves of transgenic plants deteriorated prematurely with declining photosynthesis prior to severe necrotic spotting. Necrotic spotting advanced most rapidly in the distal portion of mature leaves and was accompanied by sharp hexose increases and sharp sucrose decreases there. Leaf transcriptome profiling and network inference revealed the down-regulation of copper proteins and elevated expression of copper microRNAs prior to noticeable leaf injury. Our results suggest ectopic expression of PtaSUT1 altered sucrose partitioning in stems with systemic effects on leaf health and copper homeostasis mediated in part by sucrose-sensitive copper miRNAs.

The Dectes stem borer, Dectes texanus LeConte (Coleoptera: Cerambycidae), can significantly reduce yields by causing significant lodging in soybean. While this stem borer has not been considered a major pest of soybean, damage from it is increasing in the United States Midwest region with no current elite cultivars found resistant. Our objective was to map quantitative trait loci (QTL) that reduce girdled stems caused by Dectes stem borer infection and infestation of Dectes stem borer. A genome-wide association study (GWAS) using 50,000 single nucleotide polymorphisms was used to analyze data from a population of maturity group (MG) V to VII soybean accessions grown in North Carolina, which had been scored for Dectes stem borer larvae infestation and girdled stems caused by Dectes stem borer infestation. The GWAS identified 3 QTL with reduced larvae infestation and 4 QTL for reduced girdled stems. Allele effects ranged from 1% to 9% reduced larvae infestation or girdled stems. The QTL identified and germplasm containing the beneficial alleles can be used for improving resistance to the damage caused by the Dectes stem borer in elite soybean cultivars.