The level of phytohormones such as abscisic acid (ABA) and auxins (Aux) changes dynamically during embryogenesis. Knowledge of the transcriptional activity of the genes of their metabolic pathways is essential for a deeper understanding of embryogenesis itself; however, it could also help breeding programs of important plants, such as Cannabis sativa, attractive for the pharmaceutical, textile, cosmetic, and food industries. This work aimed to find out how genes of metabolic pathways of Aux (IAA-1, IAA-2, X15-1, X15-2) and ABA (PP2C-1) alongside one member of the LEA gene family (CanLea34) are expressed in embryos depending on the developmental stage and the embryo cultivation in vitro. Walking stick (WS) and mature (M) cultivated and uncultivated embryos of C. sativa cultivars 'KC Dora' and 'USO 31' were analyzed. The RT-qPCR results indicated that for the development of immature (VH) embryos, the genes (IAA-1, IAA-2) are likely to be fundamental. Only an increased expression of the CanLea34 gene was characteristic of the fully maturated (M) embryos. In addition, this feature was significantly increased by cultivation. In conclusion, the cultivation led to the upsurge of expression of all studied genes.

• Keywords
• Cannabis sativa, LEA gene, RT-qPCR, abscisic acid, auxin, embryo cultures, embryogenesis, gene expression,
• Publication type
• Journal Article MeSH

Mineral nutrition is one of the key environmental factors determining plant development and growth. Nitrate is the major form of macronutrient nitrogen that plants take up from the soil. Fluctuating availability or deficiency of this element severely limits plant growth and negatively affects crop production in the agricultural system. To cope with the heterogeneity of nitrate distribution in soil, plants evolved a complex regulatory mechanism that allows rapid adjustment of physiological and developmental processes to the status of this nutrient. The root, as a major exploitation organ that controls the uptake of nitrate to the plant body, acts as a regulatory hub that, according to nitrate availability, coordinates the growth and development of other plant organs. Here, we identified a regulatory framework, where cytokinin response factors (CRFs) play a central role as a molecular readout of the nitrate status in roots to guide shoot adaptive developmental response. We show that nitrate-driven activation of NLP7, a master regulator of nitrate response in plants, fine tunes biosynthesis of cytokinin in roots and its translocation to shoots where it enhances expression of CRFs. CRFs, through direct transcriptional regulation of PIN auxin transporters, promote the flow of auxin and thereby stimulate the development of shoot organs.

• Keywords
• macronutrient, nitrate, plant development,
• MeSH
• Cytokinins metabolism   MeSH
• Nitrates * metabolism   MeSH
• Plant Roots metabolism   MeSH
• Indoleacetic Acids * metabolism   MeSH
• Soil MeSH
• Gene Expression Regulation, Plant MeSH
• Signal Transduction MeSH
• Plant Shoots MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytokinins MeSH
• Nitrates * MeSH
• Indoleacetic Acids * MeSH
• Soil MeSH

The spatial location and timing of plant developmental events are largely regulated by the well balanced effects of auxin and cytokinin phytohormone interplay. Together with transport, localized metabolism regulates the concentration gradients of their bioactive forms, ultimately eliciting growth responses. In order to explore the dynamics of auxin and cytokinin metabolism during early seedling growth in Theobroma cacao (cacao), we have performed auxin and cytokinin metabolite profiling in hypocotyls and root developmental sections at different times by using ultra-high-performance liquid chromatography-electrospray tandem mass spectrometry (UHPLC-MS/MS). Our work provides quantitative characterization of auxin and cytokinin metabolites throughout early root and hypocotyl development and identifies common and distinctive features of auxin and cytokinin metabolism during cacao seedling development.

• Keywords
• Theobroma cacao, auxin, cytokinin, phytohormone metabolism, root development,
• Publication type
• Journal Article MeSH

Plants as non-mobile organisms constantly integrate varying environmental signals to flexibly adapt their growth and development. Local fluctuations in water and nutrient availability, sudden changes in temperature or other abiotic and biotic stresses can trigger changes in the growth of plant organs. Multiple mutually interconnected hormonal signaling cascades act as essential endogenous translators of these exogenous signals in the adaptive responses of plants. Although the molecular backbones of hormone transduction pathways have been identified, the mechanisms underlying their interactions are largely unknown. Here, using genome wide transcriptome profiling we identify an auxin and cytokinin cross-talk component; SYNERGISTIC ON AUXIN AND CYTOKININ 1 (SYAC1), whose expression in roots is strictly dependent on both of these hormonal pathways. We show that SYAC1 is a regulator of secretory pathway, whose enhanced activity interferes with deposition of cell wall components and can fine-tune organ growth and sensitivity to soil pathogens.

• MeSH
• Arabidopsis genetics   growth & development   metabolism   MeSH
• Cell Wall chemistry   metabolism   MeSH
• Cytokinins metabolism   MeSH
• Endosomes metabolism   MeSH
• Plants, Genetically Modified metabolism   MeSH
• Golgi Apparatus metabolism   MeSH
• Plant Roots metabolism   microbiology   MeSH
• Indoleacetic Acids metabolism   MeSH
• Membrane Proteins genetics   metabolism   MeSH
• Disease Resistance genetics   MeSH
• Plasmodiophorida pathogenicity   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Soil MeSH
• Gene Expression Regulation, Plant genetics   MeSH
• Plant Growth Regulators metabolism   MeSH
• Secretory Pathway genetics   MeSH
• Gene Expression Profiling MeSH
• Transcriptome genetics   MeSH
• Vesicular Transport Proteins metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• AT2G18840 protein, Arabidopsis MeSH Browser
• AT4G30260 protein, Arabidopsis MeSH Browser
• Cytokinins MeSH
• ECHIDNA protein, Arabidopsis MeSH Browser
• Indoleacetic Acids MeSH
• Membrane Proteins MeSH
• Arabidopsis Proteins MeSH
• Soil MeSH
• Plant Growth Regulators MeSH
• SYAC1 protein, Arabidopsis MeSH Browser
• Vesicular Transport Proteins MeSH

Directional organ growth allows the plant root system to strategically cover its surroundings. Intercellular auxin transport is aligned with the gravity vector in the primary root tips, facilitating downward organ bending at the lower root flank. Here we show that cytokinin signaling functions as a lateral root specific anti-gravitropic component, promoting the radial distribution of the root system. We performed a genome-wide association study and reveal that signal peptide processing of Cytokinin Oxidase 2 (CKX2) affects its enzymatic activity and, thereby, determines the degradation of cytokinins in natural Arabidopsis thaliana accessions. Cytokinin signaling interferes with growth at the upper lateral root flank and thereby prevents downward bending. Our interdisciplinary approach proposes that two phytohormonal cues at opposite organ flanks counterbalance each other's negative impact on growth, suppressing organ growth towards gravity and allow for radial expansion of the root system.

• MeSH
• Arabidopsis physiology   MeSH
• Genome-Wide Association Study MeSH
• Cytokinins metabolism   MeSH
• Plants, Genetically Modified physiology   MeSH
• Genome, Plant genetics   MeSH
• Gravitropism MeSH
• Plant Roots metabolism   MeSH
• Oxidoreductases genetics   metabolism   MeSH
• Arabidopsis Proteins metabolism   MeSH
• Proteolysis MeSH
• Plant Growth Regulators metabolism   MeSH
• Systems Biology MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• cytokinin oxidase MeSH Browser
• Cytokinins MeSH
• Oxidoreductases MeSH
• Arabidopsis Proteins MeSH
• Plant Growth Regulators MeSH

Clubroot is a destructive soil-borne pathogen of Brassicaceae that causes significant recurrent reductions in yield of cruciferous crops. Although there is some resistance in oilseed rape (a crop type of the species Brassica napus), the genetic basis of that resistance is poorly understood. In this study, we used an associative transcriptomics approach to elucidate the genetic basis of resistance to clubroot pathotype ECD 17/31/31 across a genetic diversity panel of 245 accessions of B. napus. A single nucleotide polymorphism (SNP) association analysis was performed with 256,397 SNPs distributed across the genome of B. napus and combined with transcript abundance data of 53,889 coding DNA sequence (CDS) gene models. The SNP association analysis identified two major loci (on chromosomes A2 and A3) controlling resistance and seven minor loci. Within these were a total of 86 SNP markers. Altogether, 392 genes were found in these regions. Another 21 genes were implicated as potentially involved in resistance using gene expression marker (GEM) analysis. After GO enrichment analysis and InterPro functional analysis of the identified genes, 82 candidate genes were identified as having roles in clubroot resistance. These results provide useful information for marker-assisted breeding which could lead to acceleration of pyramiding of multiple clubroot resistance genes in new varieties.

• Keywords
• Association genetics, Brassica napus, Clubroot, Transcriptomics,
• Publication type
• Journal Article MeSH

Arabidopsis and human ARM protein interact with telomerase. Deregulated mRNA levels of DNA repair and ribosomal protein genes in an Arabidopsis arm mutant suggest non-telomeric ARM function. The human homolog ARMC6 interacts with hTRF2. Telomerase maintains telomeres and has proposed non-telomeric functions. We previously identified interaction of the C-terminal domain of Arabidopsis telomerase reverse transcriptase (AtTERT) with an armadillo/β-catenin-like repeat (ARM) containing protein. Here we explore protein-protein interactions of the ARM protein, AtTERT domains, POT1a, TRF-like family and SMH family proteins, and the chromatin remodeling protein CHR19 using bimolecular fluorescence complementation (BiFC), yeast two-hybrid (Y2H) analysis, and co-immunoprecipitation. The ARM protein interacts with both the N- and C-terminal domains of AtTERT in different cellular compartments. ARM interacts with CHR19 and TRF-like I family proteins that also bind AtTERT directly or through interaction with POT1a. The putative human ARM homolog co-precipitates telomerase activity and interacts with hTRF2 protein in vitro. Analysis of Arabidopsis arm mutants shows no obvious changes in telomere length or telomerase activity, suggesting that ARM is not essential for telomere maintenance. The observed interactions with telomerase and Myb-like domain proteins (TRF-like family I) may therefore reflect possible non-telomeric functions. Transcript levels of several DNA repair and ribosomal genes are affected in arm mutants, and ARM, likely in association with other proteins, suppressed expression of XRCC3 and RPSAA promoter constructs in luciferase reporter assays. In conclusion, ARM can participate in non-telomeric functions of telomerase, and can also perform its own telomerase-independent functions.

• Keywords
• ARMC6, Armadillo/β-catenin-like repeat, AtTERT, Homologous recombination, Protein–protein interaction, Telomerase activity,
• MeSH
• Arabidopsis enzymology   genetics   MeSH
• Holoenzymes MeSH
• Humans MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Armadillo Domain Proteins genetics   metabolism   MeSH
• Genes, Reporter MeSH
• Two-Hybrid System Techniques MeSH
• Telomerase genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ARMC6 protein, human MeSH Browser
• Holoenzymes MeSH
• Arabidopsis Proteins MeSH
• Armadillo Domain Proteins MeSH
• Telomerase MeSH

The Arabidopsis (Arabidopsis thaliana) gynoecium consists of two congenitally fused carpels made up of two lateral valve domains and two medial domains, which retain meristematic properties and later fuse to produce the female reproductive structures vital for fertilization. Polar auxin transport (PAT) is important for setting up distinct apical auxin signaling domains in the early floral meristem remnants allowing for lateral domain identity and outgrowth. Crosstalk between auxin and cytokinin plays an important role in the development of other meristematic tissues, but hormone interaction studies to date have focused on more accessible later-stage gynoecia and the spatiotemporal interactions pivotal for patterning of early gynoecium primordia remain unknown. Focusing on the earliest stages, we propose a cytokinin-auxin feedback model during early gynoecium patterning and hormone homeostasis. Our results suggest that cytokinin positively regulates auxin signaling in the incipient gynoecial primordium and strengthen the concept that cytokinin regulates auxin homeostasis during gynoecium development. Specifically, medial cytokinin promotes auxin biosynthesis components [YUCCA1/4 (YUC1/4)] in, and PINFORMED7 (PIN7)-mediated auxin efflux from, the medial domain. The resulting laterally focused auxin signaling triggers ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN6 (AHP6), which then represses cytokinin signaling in a PAT-dependent feedback. Cytokinin also down-regulates PIN3, promoting auxin accumulation in the apex. The yuc1, yuc4, and ahp6 mutants are hypersensitive to exogenous cytokinin and 1-napthylphthalamic acid (NPA), highlighting their role in mediolateral gynoecium patterning. In summary, these mechanisms self-regulate cytokinin and auxin signaling domains, ensuring correct domain specification and gynoecium development.

• MeSH
• Arabidopsis embryology   genetics   metabolism   MeSH
• Models, Biological MeSH
• Biological Transport MeSH
• Cytokinins metabolism   MeSH
• Homeostasis MeSH
• Flowers embryology   MeSH
• Indoleacetic Acids metabolism   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Plant Growth Regulators metabolism   MeSH
• Genes, Plant MeSH
• Body Patterning * MeSH
• Signal Transduction * MeSH
• Up-Regulation MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cytokinins MeSH
• Indoleacetic Acids MeSH
• Arabidopsis Proteins MeSH
• Plant Growth Regulators MeSH

This article comments on: Kong Q, Ma W, Yang H, Ma G, Mantyla JJ, Benning C. 2017. The Arabidopsis WRINKLED1 transcription factor affects auxin homeostasis in roots. Journal of Experimental Botany 68, 4627–4634.

• Keywords
• Arabidopsis, GH3, IAA conjugation, PIN expression, endoplasmic reticulum, polar auxin transport, transcriptional regulation,
• MeSH
• Arabidopsis MeSH
• Biological Transport MeSH
• Indoleacetic Acids * MeSH
• Membrane Transport Proteins genetics   MeSH
• Arabidopsis Proteins genetics   MeSH
• Gene Expression Regulation, Plant MeSH
• Publication type
• Journal Article MeSH
• Comment MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Indoleacetic Acids * MeSH
• Membrane Transport Proteins MeSH
• Arabidopsis Proteins MeSH