The CRC orthologue from Pisum sativum shows conserved functions in carpel morphogenesis and vascular development

[EN] CRABS CLAW (CRC) is a member of the YABBY family of transcription factors involved in carpel morphogenesis, floral determinacy and nectary specification in arabidopsis. CRC orthologues have been functionally characterized across angiosperms, revealing additional roles in leaf vascular development and carpel identity specification in Poaceae. These studies support an ancestral role of CRC orthologues in carpel development, while roles in vascular development and nectary specification appear to be derived. This study aimed to expand research on CRC functional conservation to the legume family in order to better understand the evolutionary history of CRC orthologues in angiosperms. CRC orthologues from Pisum sativum and Medicago truncatula were identified. RNA in situ hybridization experiments determined the corresponding expression patterns throughout flower development. The phenotypic effects of reduced CRC activity were investigated in P. sativum using virus-induced gene silencing. CRC orthologues from P. sativum and M. truncatula showed similar expression patterns, mainly restricted to carpels and nectaries. However, these expression patterns differed from those of other core eudicots, most importantly in a lack of abaxial expression in the carpel and in atypical expression associated with the medial vein of the ovary. CRC downregulation in pea caused defects in carpel fusion and style/stigma development, both typically associated with CRC function in eudicots, but also affected vascular development in the carpel. The data support the conserved roles of CRC orthologues in carpel fusion, style/stigma development and nectary development. In addition, an intriguing new aspect of CRC function in legumes was the unexpected role in vascular development, which could be shared by other species from widely diverged clades within the angiosperms, suggesting that this role could be ancestral rather than derived, as so far generally accepted.We thank Rafael Martinez-Pardo (IBMCP) for greenhouse support, Alejandro Terrones (IBMCP) for technical assistance and Elisabeth Johansen (University of Aarhus, Denmark) for providing VIGS plasmids and technical advice. This work was supported by the Spanish Ministerio de Ciencia e Innovacion (BIO2009-09920), the Spanish Ministerio de Economia y Competitividad (BIO2012-32902) and the Generalitat Valenciana (ACOMP/2012/099).Fourquin ., C.; Primo-Capella, A.; Martinez-Fernandez, I.; Huet-Trujillo, E.; Ferrandiz Maestre, C. (2014). The CRC orthologue from Pisum sativum shows conserved functions in carpel morphogenesis and vascular development. Annals of Botany. 114(7):1535-1544. https://doi.org/10.1093/aob/mcu129S15351544114

Quartet Sampling distinguishes lack of support from conflicting support in the green plant tree of life

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/1/ajb21016-sup-0009-AppendixS9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/2/ajb21016.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/3/ajb21016-sup-0004-AppendixS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/4/ajb21016-sup-0001-AppendixS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/5/ajb21016-sup-0002-AppendixS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/6/ajb21016_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/7/ajb21016-sup-0005-AppendixS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/8/ajb21016-sup-0006-AppendixS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/9/ajb21016-sup-0008-AppendixS8.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/10/ajb21016-sup-0003-AppendixS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143738/11/ajb21016-sup-0007-AppendixS7.pd

Diversity and Evolution of Sensor Histidine Kinases in Eukaryotes

Histidine kinases (HKs) are primary sensor proteins that act in cell signaling pathways generically referred to as "two component systems" (TCSs). TCSs are among the most widely distributed transduction systems used by both prokaryotic and eukaryotic organisms to detect and respond to a broad range of environmental cues. The structure and distribution of HK proteins are now well documented in prokaryotes but information is still fragmentary for eukaryotes. Here, we have taken advantage of recent genomic resources to explore the structural diversity and the phylogenetic distribution of HKs in the prominent eukaryotic supergroups. Searches of the genomes of 67 eukaryotic species spread evenly throughout the phylogenetic tree of life identified 748 predicted HK proteins. Independent phylogenetic analyses of predicted HK proteins were carried out for each of the major eukaryotic supergroups. This allowed most of the compiled sequences to be categorised into previously described HK groups. Beyond the phylogenetic analysis of eukaryotic HKs, this study revealed some interesting findings: (i) characterisation of some previously undescribed eukaryotic HK groups with predicted functions putatively related to physiological traits; (ii) discovery of HK groups that were previously believed to be restricted to a single kingdom in additional supergroups and (iii) indications that some evolutionary paths have led to the appearance, transfer, duplication, and loss of HK genes in some phylogenetic lineages. This study provides an unprecedented overview of the structure and distribution of HKs in the Eukaryota and represents a first step towards deciphering the evolution of TCS signaling in living organisms

Cytokinin-induced promotion of root meristem size in the fern Azolla supports a shoot-like origin of euphyllophyte roots

de Vries J, Fischer AM, Roettger M, et al. Cytokinin-induced promotion of root meristem size in the fern Azolla supports a shoot-like origin of euphyllophyte roots. New Phytologist. 2016;209(2):705-720.The phytohormones cytokinin and auxin orchestrate the root meristem development in angiosperms by determining embryonic bipolarity. Ferns, having the most basal euphyllophyte root, form neither bipolar embryos nor permanent embryonic primary roots but rather an adventitious root system. This raises the questions of how auxin and cytokinin govern fern root system architecture and whether this can tell us something about the origin of that root. Using Azolla filiculoides, we characterized the influence of IAA and zeatin on adventitious fern root meristems and vasculature by Nomarski microscopy. Simultaneously, RNAseq analyses, yielding 36 091 contigs, were used to uncover how the phytohormones affect root tip gene expression. We show that auxin restricts Azolla root meristem development, while cytokinin promotes it; it is the opposite effect of what is observed in Arabidopsis. Global gene expression profiling uncovered 145 genes significantly regulated by cytokinin or auxin, including cell wall modulators, cell division regulators and lateral root formation coordinators. Our data illuminate both evolution and development of fern roots. Promotion of meristem size through cytokinin supports the idea that root meristems of euphyllophytes evolved from shoot meristems. The foundation of these roots was laid in a postembryonically branching shoot system

Deep sequencing of the Mexican avocado transcriptome, an ancient angiosperm with a high content of fatty acids

Background: Avocado (Persea americana) is an economically important tropical fruit considered to be a good source of fatty acids. Despite its importance, the molecular and cellular characterization of biochemical and developmental processes in avocado is limited due to the lack of transcriptome and genomic information. Results: The transcriptomes of seeds, roots, stems, leaves, aerial buds and flowers were determined using different sequencing platforms. Additionally, the transcriptomes of three different stages of fruit ripening (pre-climacteric, climacteric and post-climacteric) were also analyzed. The analysis of the RNAseqatlas presented here reveals strong differences in gene expression patterns between different organs, especially between root and flower, but also reveals similarities among the gene expression patterns in other organs, such as stem, leaves and aerial buds (vegetative organs) or seed and fruit (storage organs). Important regulators, functional categories, and differentially expressed genes involved in avocado fruit ripening were identified. Additionally, to demonstrate the utility of the avocado gene expression atlas, we investigated the expression patterns of genes implicated in fatty acid metabolism and fruit ripening. Conclusions: A description of transcriptomic changes occurring during fruit ripening was obtained in Mexican avocado, contributing to a dynamic view of the expression patterns of genes involved in fatty acid biosynthesis and the fruit ripening process