Plant Direct最新文献

Plant growth and development rely on a delicate balance between cell proliferation and cell differentiation. The root apical meristem (RAM) of Arabidopsis thaliana is an excellent model to study the cell cycle due to the coordinated relationship between nucleus shape and cell size at each stage, allowing for precise estimation of the cell cycle duration. In this study, we present a method for high-resolution visualization of RAM cells. This is the first protocol that allows for simultaneous high-resolution imaging of cellular and nuclear stains, being compatible with DNA replication markers such as EdU, including fluorescent proteins (H2B::YFP), SYTOX DNA stains, and the cell wall stain SR2200. This protocol includes a clarification procedure that enables the acquisition of high-resolution 3D images, suitable for detailed subsequent analysis.

Plants exhibit strong plasticity in growth and development, seen clearly in lateral and adventitious root development from differentiated tissues in response to environmental stresses. Previous studies have demonstrated the role of both auxin-dependent and auxin-independent signaling pathways in regulating the de novo formation of adventitious roots (ARs) from differentiated tissues, such as leaf petiole in Arabidopsis. One important question is how the auxin-dependent and auxin-independent pathways are coordinated. To investigate this question, we used a combined approach of inducible gene expression, mutant, and signaling reporter gene analysis during AR regeneration in the Arabidopsis petiole to understand regulatory relationships. Auxin signaling components AXR1 and AXR3 are each required for both AR and subsequent lateral root (LR) initiation, as is the ethylene signaling repressor POLARIS, but not EIN2. The PIN trafficking SNARE protein VAMP714 is required for LR rather than AR formation, through effects on auxin-induced gene expression. We identify the RNA splicing regulator MDF and the transcription factor RAP2.7 as new positive regulators of both the auxin-independent and auxin-dependent pathways, and show that MDF regulates RAP2.7, WOX5, and NAC1 while RAP2.7 regulates WOX5 but not NAC1 or YUC1. NAC1 is required for de novo root formation in a pathway independent of YUC1, WOX5, or RAP2.7. We propose a model in which MDF represents a point of molecular crosstalk between auxin-dependent and auxin-independent regeneration processes.

For most species, transcriptome data are much more readily available than genome data. Without a reference genome, gene calling is cumbersome and inaccurate because of the high degree of redundancy in de novo transcriptome assemblies. To simplify and increase the accuracy of de novo transcriptome assembly in the absence of a reference genome, we developed UnigeneFinder. Combining several clustering methods, UnigeneFinder substantially reduces the redundancy typical of raw transcriptome assemblies. This pipeline offers an effective solution to the problem of inflated transcript numbers, achieving a closer representation of the actual underlying genome. UnigeneFinder performs comparably or better, compared with existing tools, on plant species with varying genome complexities. UnigeneFinder is the only available transcriptome redundancy solution that fully automates the generation of primary transcript, coding region, and protein sequences, analogous to those available for high-quality reference genomes. These features, coupled with the pipeline's cross-platform implementation, focus on automation, and an accessible, user-friendly interface, make UnigeneFinder a useful tool for many downstream sequence-based analyses in nonmodel organisms lacking a reference genome, including differential gene expression analysis, accurate ortholog identification, functional enrichments, and evolutionary analyses. UnigeneFinder also runs efficiently both on high-performance computing (HPC) systems and personal computers, further reducing barriers to use.

The photoperiod in controlled environment agriculture can be adjusted to minimize electricity consumption, even if it differs from the plant's circadian rhythm. Daily modifications of the photoperiod disrupt the plant's circadian resonance state, resulting in altered growth and yield. However, the effects of periodic, rather than daily, photoperiod adjustments remain less understood. This study aims to investigate the effects of a 4-h extension of the dark period every 3 days on the circadian regulation of photosynthetic activity and sugar content, as well as on lettuce yield. Control lettuces were grown under a 16/8 photoperiod, while EPD lettuces ("Exceptionally long Period of Darkness") were grown under a repeated 16/12-16/8-16/8 photoperiod pattern from the beginning to the end of cultivation. The experiment was repeated twice, and the 4-h extension induced a loss of photosynthetic activity of 7% and 11% during the following lighting period in the first and second experiments, respectively. The yields were not affected. The stomatal conductance followed the circadian rhythm of lettuce rather than directly responding to photoperiod modifications. Furthermore, no long-term changes in starch and sucrose content were observed. Taken together, these results show that extending the dark period by 4 h every 3 days did not cause long-term disruption of the circadian regulation of photosynthesis and sugar levels in lettuce. These results provide new insights for optimizing light management in controlled environment agriculture, suggesting that the management of dark periods is crucial for maintaining yields and reducing energy consumption.

Hydrogen peroxide (H₂O₂) is a signaling molecule that plays a crucial role in plant growth and development against different abiotic stresses. Identifying genetic factors associated with H₂O₂ regulation and homeostasis can provide valuable insights for improving stress tolerance. Here, we explored genetic diversity of root and shoot traits mediated by H₂O₂ using a global diversity panel of 150 bread wheat cultivars. The H₂O₂ treatment significantly reduced root and shoot growth. We calculated relative values and stress tolerance index (STI) of root and shoot traits and performed genome-wide association studies (GWAS). This led to identification of 108 marker-trait associations including the topmost associations on chromosomes 3B, 2A, 5A, 3B, 5D, 5A, 6B, 4B, and 3B for relative root length, STI root length, relative shoot length, STI shoot length, relative root fresh weight, relative shoot fresh weight, STI shoot fresh weight, and relative and STI root-shoot ratio, respectively. Linkage disequilibrium analysis revealed that major alleles of significant markers were linked with high relative values and STIs for all traits except for relative root length and relative root-shoot ratio. The selected candidate genes were involved mostly in metal ion binding, transmembrane transport, oxidation-reduction process, protein phosphorylation, DNA, and ADP binding processes. These findings provide a fundamental basis for functional analysis of putative candidate genes linked to H₂O₂-mediated root-shoot growth of wheat. The result will also help to construct genetic map for H₂O₂-mediated root-shoot growth variation.

In dense canopies, light becomes a limiting factor for plant growth. Many plants respond to neighbor cues by growing taller to improve light capture, a phenomenon known as the shade avoidance syndrome (SAS). The major neighbor detection is via enrichment of far-red (FR) light that leads to a low red:far-red light ratio (R:FR), suppressing phytochrome activity. In tomato, low R:FR induces elongation of the internodes, but study into the role of different cell types in this response has remained limited. We characterized changes in cellular anatomy of the tomato internode in response to low R:FR and its accompanying changes in gene expression. We observed changes to the pith traits, including increases in pith layer number, pith cell diameter, and longitudinal cell length. We profiled the transcriptome in the entire internodes and in the hand-dissected pith in the central cylinder of the internode in response to low R:FR treatment and identified transcription factors (TFs) of interest that were upregulated in the central cylinder, mostly GATA, TCP, and bZIPs. We then characterized FR responses in eight dicotyledonous species. Significant pith elongation was observed in species that exhibited a strong internode elongation response. The FR-responsive expression of homologs of target GATA, TCP, and bZIP TFs in the central cylinder was conserved within the Solanaceae family. Overall, we discovered central cylinder gene expression patterns in SAS that are distinct from those of the entire internode, suggesting that some responses are unique and likely specific to vascular cell types such as pith. These patterns were conserved with close relatives of tomato but not in other dicot families we sampled, indicating that different molecular mechanisms drive FR responses in different dicots.

Day neutrality, or insensitivity to photoperiod (day length), is an important domestication trait in many crop species. Although the oilseed crop C. sativa has been cultivated since the Neolithic era, day-neutral accessions have yet to be described. We sought to leverage genetic diversity in existing germplasms to identify C. sativa accessions with low photoperiod sensitivity for future engineering of this trait. To do so, we quantified variation in hypocotyl length across 161 C. sativa accessions of 4-day-old seedlings grown in long-day and short-day conditions as a high-throughput approximation of variation in the photoperiod response. Soil-grown adult plants from selected accessions also showed variation in the response to day length in several traits; however, the responses in seedling and adult traits were not correlated, suggesting complex mechanistic underpinnings. Although RNA-seq experiments of the reference accession Licalla identified several differentially regulated Arabidopsis syntelogs involved in photoperiod response and development, including COL2, FT, LHY, and WOX4, expression of these genes in the accessions did not correlate with differences in their photoperiod sensitivity. Taken together, we show that all tested accessions show some degree of photoperiod response and that this trait is likely complex, involving several and separable seedling and adult traits.

Silique dehiscence, despite being an essential physiological process for seed dispersal for dehiscent fruits, is disadvantageous for the agricultural industry. While crops have been selected against the expression of natural, spontaneous shattering to protect the seeds for harvest, fruit dehiscence in the field can be promoted through abiotic factors such as wind, drought, and hail that can be detrimental in reducing crop yield and profitability. In crops like canola, pennycress, and Camelina, this impact could be as high as 50%, creating economic losses for both the industry and the economy. Mitigating the effects of fruit dehiscence is crucial to prevent seed loss, economic loss, and the persistence of volunteer plants, which interfere with crop rotation and require increased weed control. Developing agronomic traits through genetic manipulation to enhance the strength of the fruiting body can prevent seed dispersal mechanisms from occurring and boost yield efficiency and preservation. Current research into this area has created mutant plants with indehiscent fruits by reducing allele function that determines the identity of the various anatomical layers of the fruit. Future genetic approaches may focus on strengthening siliques by enhancing secondary cell walls through either increased lignification or reducing cell wall-degrading enzymes to achieve shatter tolerance. This review focuses on improving our knowledge within members of the Brassicaceae family to create a better understanding of silique/silicle dehiscence for researchers to establish a groundwork for broader applications across diverse crops. This knowledge will directly lead to improved agricultural productivity and ensure a stable food supply, addressing global challenges the world is facing.

Pectins are abundant in the cell walls of eudicot plants and have been implicated in determining the development and biomechanics of stomatal guard cells, which expand and contract dynamically to open and close stomatal pores on the plant surface, modulating photosynthesis and water transport. Pectic homogalacturonan is delivered to the cell wall in a methylesterified form but can be demethylesterified in the wall by pectin methylesterases, increasing both its ability to form crosslinks via calcium and its susceptibility to degradation by endogenous pectinases. Although a few pectin methylesterases have been implicated in stomatal development and function, this large family of proteins has not been fully characterized with respect to how they modulate stomatal guard cells. Here, we characterized the function of PECTIN METHYLESTERASE51 (PME51), a pectin methylesterase-encoding gene that is expressed in developing guard cells, in stomatal morphogenesis in seedlings and adult plants of Arabidopsis thaliana. Overexpressing PME51 led to smaller adult plants with smaller stomatal complexes and subtle changes in initial responses to opening and closure stimuli, whereas knocking out PME51 resulted in smaller stomatal complexes and longer roots in seedlings. We observed changes in pectin labeling in knockout and overexpression plants that imply a specific function for PME51 in modulating the degree of methylesterification for homogalacturonan. Together, these findings expand our understanding of how pectin modification by pectin methylesterases affects the development and function of stomatal guard cells, which must maintain a balance of strength and flexibility to optimize plant growth.

Sprout suppressants are widely used in industry to ensure year-round availability of potato tubers, significantly decreasing wastage by repressing premature growth of buds on the tuber surface during storage. Despite its ban from 2020 in the EU, isopropyl N-(3-chlorophenyl) carbamate (also known as chlorpropham or CIPC) remains the most widely used suppressant worldwide. However, the mechanism of action of CIPC remains obscure. Here, we report on a combined targeted transcriptomic and genetic approach to identify components in the tuber bud cell-division machinery that might be involved in CIPC's mode of action. This involved RNAseq analysis of dissected, staged tuber buds during in vitro sprouting with and without CIPC to identify lead genes, followed by the development and application of an Arabidopsis root assay to assess cell division response to CIPC in selected mutants. The ease of use of this model plant, coupled with its immense genetic resources, allowed us to test the functionality of lead genes encoding cell-division-associated proteins in the modulation of plant growth response to CIPC. This approach led to the identification of a component of the augmin complex (a core player in mitosis) as a potential target for CIPC.