The Use of Arabidopsis thaliana to Characterize the Production and Action Stages of the Plant MicroRNA Pathway.

Plant microRNAs are an endogenous class of small regulatory RNA central to the posttranscriptional control of gene expression as part of normal development to adapt to environmental stress and respond to pathogen challenges. The plant microRNA pathway is separated into two distinct stages: (1) production stage, which is localized to the nucleus of the cell and, in this cell compartment, the microRNA silencing signal is processed from its double-stranded RNA precursor transcript, and (2) action stage, which is localized to the cytoplasm of the cell. It is in this cellular compartment where the now mature microRNA functions as a regulatory RNA molecule to control target gene expression via its loading into the protein effector complex termed microRNA-induced silencing complex.

DRB1 and DRB2 Are Required for an Appropriate miRNA-Mediated Molecular Response to Salt Stress in .

In plants, microRNAs (miRNAs) and their target genes have been demonstrated to form an essential component of the molecular response to salt stress. In (), DOUBLE-STRANDED RNA BINDING1 (DRB1) and DRB2 are required to produce specific miRNA populations throughout normal development and in response to abiotic stress. The phenotypic and physiological assessment of 15-day-old wild-type seedlings, and of the and mutants following a 7-day period of salt stress, revealed the mutant to be more sensitive to salt stress than the mutant.

The Double-Stranded RNA Binding Proteins DRB1 and DRB2 Are Required for miR160-Mediated Responses to Exogenous Auxin.

DOUBLE-STRANDED RNA BINDING (DRB) proteins DRB1, DRB2, and DRB4 are essential for microRNA (miRNA) production in () with miR160, and its target genes, (), , and , forming an auxin responsive miRNA expression module crucial for root development. : Wild-type plants (Columbia-0 (Col-0)) and the , , and mutants were treated with the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D), and the miR160-mediated response of these four lines was phenotypically and molecularly characterized. : In 2,4-D-treated Col-0, and plants, altered miR160 abundance and , , and gene expression were associated with altered root system development.

DRB1, DRB2 and DRB4 Are Required for an Appropriate miRNA-Mediated Molecular Response to Osmotic Stress in .

() double-stranded RNA binding (DRB) proteins DRB1, DRB2 and DRB4 perform essential roles in microRNA (miRNA) production, with many of the produced miRNAs mediating aspects of the molecular response of to abiotic stress. Exposure of the , and mutants to mannitol stress showed to be the most sensitive to this form of osmotic stress. Profiling of the miRNA landscapes of mannitol-stressed , and seedlings via small RNA sequencing, and comparison of these to the profile of mannitol-stressed wild-type plants, revealed that the ability of the and mutants to mount an appropriate miRNA-mediated molecular response to mannitol stress was defective.

Molecular Manipulation of the miR160/ Expression Module Impacts Root Development in .

In (), microRNA160 (miR160) regulates the expression of (), and throughout development, including the development of the root system. We have previously shown that in addition to DOUBLE-STRANDED RNA BINDING1 (DRB1), DRB2 is also involved in controlling the rate of production of specific miRNA cohorts in the tissues where is expressed in wild-type plants. In this study, a miR160 overexpression transgene () and miR160-resistant transgene versions of and ( and ) were introduced into wild-type plants and the and single mutants to determine the degree of requirement of DRB2 to regulate the miR160 expression module as part of root development.

STP13.1 is an H-coupled monosaccharide transporter, present in source leaves and seed coats, with higher substrate affinity at depolarized potentials.

Sugar transport proteins (STPs) are high-affinity H-coupled hexose symporters. Recently, the contribution of STP13 to bacterial and fungal pathogen resistance across multiple plant species has garnered significant interest. Quantitative PCR analysis of source leaves, developing embryos, and seed coats of .

Sugar loading of crop seeds - a partnership of phloem, plasmodesmal and membrane transport.

Sugar loading of developing seeds comprises a cohort of transport events that contribute to reproductive success and seed yield. Understanding these events is most advanced for grain crops (Brassicaceae, Fabaceae and Gramineae) and Arabidopsis. For these species, 75-80% of their final seed biomass is derived from phloem-imported sucrose.

Miniature Inverted-Repeat Transposable Elements: Small DNA Transposons That Have Contributed to Plant Gene Evolution.

Angiosperms form the largest phylum within the Plantae kingdom and show remarkable genetic variation due to the considerable difference in the nuclear genome size of each species. Transposable elements (TEs), mobile DNA sequences that can amplify and change their chromosome position, account for much of the difference in nuclear genome size between individual angiosperm species. Considering the dramatic consequences of TE movement, including the complete loss of gene function, it is unsurprising that the angiosperms have developed elegant molecular strategies to control TE amplification and movement.

Genetic Variants Associated with Long-Terminal Repeats Can Diagnostically Classify Varieties.

() has recently been legalized in multiple countries globally for either its recreational or medicinal use. This, in turn, has led to a marked increase in the number of varieties available for use in either market. However, little information currently exists on the genetic distinction between adopted varieties.

Molecular Manipulation of the miR396 and miR399 Expression Modules Alters the Response of to Phosphate Stress.

In plant cells, the molecular and metabolic processes of nucleic acid synthesis, phospholipid production, coenzyme activation and the generation of the vast amount of chemical energy required to drive these processes relies on an adequate supply of the essential macronutrient, phosphorous (P). The requirement of an appropriate level of P in plant cells is evidenced by the intricately linked molecular mechanisms of P sensing, signaling and transport. One such mechanism is the posttranscriptional regulation of the P response pathway by the highly conserved plant microRNA (miRNA), miR399.

: Interdisciplinary Strategies and Avenues for Medical and Commercial Progression Outside of CBD and THC.

() is one of the world's most well-known, yet maligned plant species. However, significant recent research is starting to unveil the potential of to produce secondary compounds that may offer a suite of medical benefits, elevating this unique plant species from its illicit narcotic status into a genuine biopharmaceutical. This review summarises the lengthy history of and details the molecular pathways that underpin the production of key secondary metabolites that may confer medical efficacy.

MicroRNA-Mediated Responses to Cadmium Stress in .

In recent decades, the presence of cadmium (Cd) in the environment has increased significantly due to anthropogenic activities. Cd is taken up from the soil by plant roots for its subsequent translocation to shoots. However, Cd is a non-essential heavy metal and is therefore toxic to plants when it over-accumulates.

Molecular Manipulation of the miR399/ Expression Module Alters the Salt Stress Response of .

In (), the microRNA399 (miR399)/ () expression module is central to the response of to phosphate (PO) stress. In addition, miR399 has been demonstrated to also alter in abundance in response to salt stress. We therefore used a molecular modification approach to alter miR399 abundance to investigate the requirement of altered miR399 abundance in in response to salt stress.

Molecular Manipulation of MicroRNA397 Abundance Influences the Development and Salt Stress Response of .

() has been used extensively as a heterologous system for molecular manipulation to genetically characterize both dicotyledonous and monocotyledonous plant species. Here, we report on transformant lines molecularly manipulated to over-accumulate the small regulatory RNA microRNA397 (miR397) from the emerging C monocotyledonous grass model species (). The generated transformant lines, termed plants, displayed a range of developmental phenotypes that ranged from a mild, wild-type-like phenotype, to a severe, full dwarfism phenotype.

DRB1, DRB2 and DRB4 Are Required for Appropriate Regulation of the microRNA399/ Expression Module in .

Adequate phosphorous (P) is essential to plant cells to ensure normal plant growth and development. Therefore, plants employ elegant mechanisms to regulate P abundance across their developmentally distinct tissues. One such mechanism is PHOSPHATE2 (PHO2)-directed ubiquitin-mediated degradation of a cohort of phosphate (PO) transporters.

Profiling the Abiotic Stress Responsive microRNA Landscape of .

It is well established among interdisciplinary researchers that there is an urgent need to address the negative impacts that accompany climate change. One such negative impact is the increased prevalence of unfavorable environmental conditions that significantly contribute to reduced agricultural yield. Plant microRNAs (miRNAs) are key gene expression regulators that control development, defense against invading pathogens and adaptation to abiotic stress.

The Plant microRNA Pathway: The Production and Action Stages.

Plant microRNAs are an endogenous class of small regulatory RNA central to the posttranscriptional regulation of gene expression in plant development and environmental stress adaptation or in response to pathogen challenge. The plant microRNA pathway is readily separated into two distinct stages: (1) the production stage, which is localized to the plant cell nucleus and where the microRNA small RNA is processed from a double-stranded RNA precursor transcript, and (2) the action stage, which is localized to the plant cell cytoplasm and where the mature microRNA small RNA is loaded into an effector complex and is used by the complex as a sequence specificity guide to direct expression repression of target genes harboring highly complementary microRNA target sequences. Historical research indicated that the plant microRNA pathway was a highly structured, almost linear pathway requiring a small set of core machinery proteins.

Roles of Aquaporins in Stem Development and Sugar Storage.

is a C grass used as a model for bioenergy feedstocks. The elongating internodes in developing stems grow from an intercalary meristem at the base, and progress acropetally toward fully expanded cells that store sugar. During stem development and maturation, water flow is a driver of cell expansion and sugar delivery.