Profiling of 1-aminocyclopropane-1-carboxylic acid and selected phytohormones in Arabidopsis using liquid chromatography-tandem mass spectrometry.

Background: Gaseous phytohormone ethylene levels are directly influenced by the production of its immediate non-volatile precursor 1-aminocyclopropane-1-carboxylic acid (ACC). Owing to the strongly acidic character of the ACC molecule, its quantification has been difficult to perform. Here, we present a simple and straightforward validated method for accurate quantification of not only ACC levels, but also major members of other important phytohormonal classes - auxins, cytokinins, jasmonic acid, abscisic acid and salicylic acid from the same biological sample.

Inactivation of the entire Arabidopsis group II GH3s confers tolerance to salinity and water deficit.

Indole-3-acetic acid (IAA) controls a plethora of developmental processes. Thus, regulation of its concentration is of great relevance for plant performance. Cellular IAA concentration depends on its transport, biosynthesis and the various pathways for IAA inactivation, including oxidation and conjugation.

Broadening the roles of UDP-glycosyltransferases in auxin homeostasis and plant development.

The levels of the important plant growth regulator indole-3-acetic acid (IAA) are tightly controlled within plant tissues to spatiotemporally orchestrate concentration gradients that drive plant growth and development. Metabolic inactivation of bioactive IAA is known to participate in the modulation of IAA maxima and minima. IAA can be irreversibly inactivated by oxidation and conjugation to aspartate and glutamate.

Dynamics of Auxin and Cytokinin Metabolism during Early Root and Hypocotyl Growth in .

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 (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).

Auxin Metabolism in Plants.

The major natural auxin in plants, indole-3-acetic acid (IAA), orchestrates a plethora of developmental responses that largely depend on the formation of auxin concentration gradients within plant tissues. Together with inter- and intracellular transport, IAA metabolism-which comprises biosynthesis, conjugation, and degradation-modulates auxin gradients and is therefore critical for plant growth. It is now very well established that IAA is mainly produced from Trp and that the IPyA pathway is a major and universally conserved biosynthetic route in plants, while other redundant pathways operate in parallel.

Conifers exhibit a characteristic inactivation of auxin to maintain tissue homeostasis.

Dynamic regulation of the concentration of the natural auxin (IAA) is essential to coordinate most of the physiological and developmental processes and responses to environmental changes. Oxidation of IAA is a major pathway to control auxin concentrations in angiosperms and, along with IAA conjugation, to respond to perturbation of IAA homeostasis. However, these regulatory mechanisms remain poorly investigated in conifers.

Epigenetic Regulation of Auxin Homeostasis.

Epigenetic regulation involves a myriad of mechanisms that regulate the expression of loci without altering the DNA sequence. These different mechanisms primarily result in modifications of the chromatin topology or DNA chemical structure that can be heritable or transient as a dynamic response to environmental cues. The phytohormone auxin plays an important role in almost every aspect of plant life via gradient formation.

Auxin Metabolism Controls Developmental Decisions in Land Plants.

Unlike animals, whose body plans are set during embryo development, plants maintain the ability to initiate new organs throughout their life cycle. Auxin is a key regulator of almost all aspects of plant development, including morphogenesis and adaptive responses. Cellular auxin concentrations influence whether a cell will divide, grow, or differentiate, thereby contributing to organ formation, growth, and ultimately plant shape.

Ultra-rapid auxin metabolite profiling for high-throughput mutant screening in Arabidopsis.

Auxin (indole-3-acetic acid, IAA) plays fundamental roles as a signalling molecule during numerous plant growth and development processes. The formation of local auxin gradients and auxin maxima/minima, which is very important for these processes, is regulated by auxin metabolism (biosynthesis, degradation, and conjugation) as well as transport. When studying auxin metabolism pathways it is crucial to combine data obtained from genetic investigations with the identification and quantification of individual metabolites.

Dioxygenase-encoding AtDAO1 gene controls IAA oxidation and homeostasis in Arabidopsis.

Auxin represents a key signal in plants, regulating almost every aspect of their growth and development. Major breakthroughs have been made dissecting the molecular basis of auxin transport, perception, and response. In contrast, how plants control the metabolism and homeostasis of the major form of auxin in plants, indole-3-acetic acid (IAA), remains unclear.

Plastid control of abaxial-adaxial patterning.

Translational regulation, exerted by the cytosolic ribosome, has been shown to participate in the establishment of abaxial-adaxial polarity in Arabidopsis thaliana: many hypomorphic and null alleles of genes encoding proteins of the cytosolic ribosome enhance the leaf polarity defects of asymmetric leaves1 (as1) and as2 mutants. Here, we report the identification of the SCABRA1 (SCA1) nuclear gene, whose loss-of-function mutations also enhance the polarity defects of the as2 mutants. In striking contrast to other previously known enhancers of the phenotypes caused by the as1 and as2 mutations, we found that SCA1 encodes a plastid-type ribosomal protein that functions as a structural component of the 70S plastid ribosome and, therefore, its role in abaxial-adaxial patterning was not expected.

Getting started in mapping-by-sequencing.

Next-generation sequencing (NGS) technologies allow the cost-effective sequencing of whole genomes and have expanded the scope of genomics to novel applications, such as the genome-wide characterization of intraspecific polymorphisms and the rapid mapping and identification of point mutations. Next-generation sequencing platforms, such as the Illumina HiSeq2000 platform, are now commercially available at affordable prices and routinely produce an enormous amount of sequence data, but their wide use is often hindered by a lack of knowledge on how to manipulate and process the information produced. In this review, we focus on the strategies that are available to geneticists who wish to incorporate these novel approaches into their research but who are not familiar with the necessary bioinformatic concepts and computational tools.

Rapid identification of angulata leaf mutations using next-generation sequencing.

Map-based (positional) cloning has traditionally been the preferred strategy for identifying the causal genes underlying the phenotypes of mutants isolated in forward genetic screens. Massively parallel sequencing technologies are enabling the rapid cloning of genes identified in such screens. We have used a combination of linkage mapping and whole-genome re-sequencing to identify the causal mutations in four loss-of-function angulata (anu) mutants.

Arabidopsis ANGULATA10 is required for thylakoid biogenesis and mesophyll development.

The chloroplasts of land plants contain internal membrane systems, the thylakoids, which are arranged in stacks called grana. Because grana have not been found in Cyanobacteria, the evolutionary origin of genes controlling the structural and functional diversification of thylakoidal membranes in land plants remains unclear. The angulata10-1 (anu10-1) mutant, which exhibits pale-green rosettes, reduced growth, and deficient leaf lateral expansion, resulting in the presence of prominent marginal teeth, was isolated.

Combined haploinsufficiency and purifying selection drive retention of RPL36a paralogs in Arabidopsis.

Whole-genome duplication events have driven to a large degree the evolution of angiosperm genomes. Although the majority of redundant gene copies after a genome duplication are lost, subfunctionalization or gene balance account for the retention of gene copies. The Arabidopsis 80S ribosome represents an excellent model to test the gene balance hypothesis as it consists of 80 ribosomal proteins, all of them encoded by genes belonging to small gene families.