Thermo-Sensitive Alternative Splicing of FLOWERING LOCUS M Is Modulated by Cyclin-Dependent Kinase G2

The ability to sense environmental temperature and to coordinate growth and development accordingly, is critical to the reproductive success of plants. Flowering time is regulated at the level of gene expression by a complex network of factors that integrate environmental and developmental cues. One of the main players, involved in modulating flowering time in response to changes in ambient temperature is FLOWERING LOCUS M (FLM). FLM transcripts can undergo extensive alternative splicing producing multiple variants, of which FLM-β and FLM-δ are the most representative. While FLM-β codes for the flowering repressor FLM protein, translation of FLM-δ has the opposite effect on flowering. Here we show that the cyclin-dependent kinase G2 (CDKG2), together with its cognate cyclin, CYCLYN L1 (CYCL1) affects the alternative splicing of FLM, balancing the levels of FLM-β and FLM-δ across the ambient temperature range. In the absence of the CDKG2/CYCL1 complex, FLM-β expression is reduced while FLM-δ is increased in a temperature dependent manner and these changes are associated with an early flowering phenotype in the cdkg2 mutant lines. In addition, we found that transcript variants retaining the full FLM intron 1 are sequestered in the cell nucleus. Strikingly, FLM intron 1 splicing is also regulated by CDKG2/CYCL1. Our results provide evidence that temperature and CDKs regulate the alternative splicing of FLM, contributing to flowering time definition

μCT trait analysis reveals morphometric differences between domesticated temperate small grain cereals and their wild relatives

Wheat and barley are two of the founder crops domesticated in the Fertile Crescent, and currently represent crops of major economic importance in temperate regions. Due to impacts on yield, quality and end-use, grain morphometric traits remain an important goal for modern breeding programmes and are believed to have been selected for by human populations. To directly and accurately assess the three-dimensional (3D) characteristics of grains, we combine X-ray microcomputed tomography (μCT) imaging techniques with bespoke image analysis tools and mathematical modelling to investigate how grain size and shape vary across wild and domesticated wheat and barley. We find that grain depth and, to a lesser extent, width are major drivers of shape change and that these traits are still relatively plastic in modern bread wheat varieties. Significant changes in grain depth are also observed to be associated with differences in ploidy. Finally, we present a model that can accurately predict the wild or domesticated status of a grain from a given taxa based on the relationship between three morphometric parameters (length, width and depth) and suggest its general applicability to both archaeological identification studies and breeding programmes.Agências financiadoras: Biotechnology and Biological Sciences Research Council (BBSRC) grant, 'National Capability in Crop Phenotyping' (BB/J004464/1); (BB/CAP1730/1) BBSRC grant, 'MAGIC CARPET' (BB/M011666/1) NERC (NE/M010805/1) ERC (339941)info:eu-repo/semantics/publishedVersio

CDKG1 Is Required for Meiotic and Somatic Recombination Intermediate Processing in Arabidopsis

The Arabidopsis (Arabidopsis thaliana) cyclin-dependent kinase G1 (CDKG1) is necessary for recombination and synapsis during male meiosis at high ambient temperature. In the cdkg1-1 mutant, synapsis is impaired and there is a dramatic reduction in the number of class I crossovers, resulting in univalents at metaphase I and pollen sterility. Here, we demonstrate that CDKG1 is necessary for the processing of recombination intermediates in the canonical ZMM recombination pathway and that loss of CDKG1 results in increased class II crossovers. While synapsis and events associated with class I crossovers are severely compromised in a cdkg1-1 mutant, they can be restored by increasing the number of recombination intermediates in the double cdkg1-1 fancm-1 mutant. Despite this, recombination intermediates are not correctly resolved, leading to the formation of chromosome aggregates at metaphase I. Our results show that CDKG1 acts early in the recombination process and is necessary to stabilize recombination intermediates. Finally, we show that the effect on recombination is not restricted to meiosis and that CDKG1 is also required for normal levels of DNA damage-induced homologous recombination in somatic tissues

Barley <i>lys3</i> mutants are unique amongst shrunken-endosperm mutants in having abnormally large embryos

Many shrunken endosperm mutants of barley (Hordeum vulgare L.) have been described and several of these are known to have lesions in starch biosynthesis genes. Here we confirm that one type of shrunken endosperm mutant, lys3 (so called because it was first identified as a high-lysine mutant) has an additional phenotype: as well as shrunken endosperm it also has enlarged embryos. The lys3 embryos have a dry weight that is 50?150% larger than normal. Observations of developing lys3 embryos suggest that they undergo a form of premature germination and the mature lys3 grains show reduced dormancy. In many respects, the phenotype of barley lys3 is similar to that of rice GIANT EMBRYO mutants (affected in the OsGE gene). However, the barley orthologue of OsGE is located on a different chromosome from Lys3. Together these results suggest that the gene underlying Lys3 is unlikely to encode a starch biosynthesis protein but rather a protein influencing grain developmentpublishersversionPeer reviewe

The role of the Arabidopsis small GTPase Arac7 (Rop9) in hormone signaling

Small GTP-binding proteins of the Rac family are important signaling switches that regulate plant growth and development due to their ability to shuttle between the inactive GDP-bound and the active GTP-bound form. The ratio between the two forms is tightly regulated in the cell. The Arabidopsis genome encodes eleven Rac proteins designated Arac1-11. Based on the C-terminus, Aracs can be divided into typeI and typeII. TypeI Aracs associate with the membrane by prenylation while typeII Aracs associate with the membrane by palmitoylation. Differences in the effector-binding region and the C-terminal hypervariable region place Arac7 in a separate phylogenetic group than the other typeII Aracs. The work described in this dissertation examines the expression patterns, functions and regulation of the Arac7 protein and provides evidence that supports a distinct role for Arac7 within type II Aracs. Arac7 expression is shown to repress auxin-induced gene expression and to enhance ABA-stimulated gene expression in Arabidopsis. Plants overexpressing Arac7 are less responsive to auxin but show increased responses to ABA while the opposite is observed in plants with decreased levels of Arac7 mRNA. Arac7 expression is high in the lateral root primordia and can be traced back to the first pericicle divisions that give rise to these primordia. This, together with the increased number of lateral roots of plants overexpressing Arac7, is consistent with a role in lateral root formation for this small GTPase. Interestingly, transcription from the Arac7 promoter is stimulated by auxin but repressed by ABA. Together with the observed functions on auxin and ABA signaling, the regulated expression of Arac7 provides a feedback mechanism to ensure that cells maintain sensitivity to signals. This work also shows that Arac7 is constitutively associated with the plasma membrane where it partitions into detergent-resistant membrane domains (DRMs). Moreover, at the plasma membrane, the majority of Arac7 partitions into high molecular weight complexes. These properties contrast with those observed for the typeI Arac5 which is distributed between the cytosol and non-DRMs regions of the plasma membrane and exists predominantly in low molecular weight forms. Together, these observations suggest different functions and regulatory mechanisms for typeI and typeII Aracs

Using Computer Vision to estimate Sphagnum colony density in the field

This dataset contains all the images used to develop an automated software able to calculate Sphagnum moss capitula density in the field as described in the linked paper. The images were acquired with a smartphone in the field and include images from 5 different Sphagnum species and 3 different sites as outlined in the read me file. The images are provided in a jpg format. Image information as well as the raw data obtained by image analysis using the developed software are also included as an excel file with 4 separate sheet

µCT imaging raw data and data analysis of small grain cereals and their wild relatives

micro CT raw data files (pre-processed tiffs) and image analysis files of grain and spike morphological traits (.csv)