Birth and Rapid Subcellular Adaptation of a Hominoid-Specific CDC14 Protein

Gene duplication was prevalent during hominoid evolution, yet little is known about the functional fate of new ape gene copies. We characterized the CDC14B cell cycle gene and the functional evolution of its hominoid-specific daughter gene, CDC14Bretro. We found that CDC14B encodes four different splice isoforms that show different subcellular localizations (nucleus or microtubule-associated) and functional properties. A microtubular CDC14B variant spawned CDC14Bretro through retroposition in the hominoid ancestor 18–25 million years ago (Mya). CDC14Bretro evolved brain-/testis-specific expression after the duplication event and experienced a short period of intense positive selection in the African ape ancestor 7–12 Mya. Using resurrected ancestral protein variants, we demonstrate that by virtue of amino acid substitutions in distinct protein regions during this time, the subcellular localization of CDC14Bretro progressively shifted from the association with microtubules (stabilizing them) to an association with the endoplasmic reticulum. CDC14Bretro evolution represents a paradigm example of rapid, selectively driven subcellular relocalization, thus revealing a novel mode for the emergence of new gene function

Water Deficit-Responsive QTLs for Cell Wall Degradability and Composition in Maize at Silage Stage

The use of lignocellulosic biomass for animal feed or biorefinery requires the optimization of its degradability. Moreover, biomass crops need to be better adapted to the changing climate and in particular to periods of drought. Although the negative impact of water deficit on biomass yield has often been mentioned, its impact on biomass quality has only been recently reported in a few species. In the present study, we combined the mapping power of a maize recombinant inbred line population with robust near infrared spectroscopy predictive equations to track the response to water deficit of traits associated with biomass quality. The population was cultivated under two contrasted water regimes over 3 consecutive years in the south of France and harvested at silage stage. We showed that cell wall degradability and β-O-4-linked H lignin subunits were increased in response to water deficit, while lignin and p-coumaric acid contents were reduced. A mixed linear model was fitted to map quantitative trait loci (QTLs) for agronomical and cell wall-related traits. These QTLs were categorized as “constitutive” (QTL with an effect whatever the irrigation condition) or “responsive” (QTL involved in the response to water deficit) QTLs. Fifteen clusters of QTLs encompassed more than two third of the 213 constitutive QTLs and 13 clusters encompassed more than 60% of the 149 responsive QTLs. Interestingly, we showed that only half of the responsive QTLs co-localized with constitutive and yield QTLs, suggesting that specific genetic factors support biomass quality response to water deficit. Overall, our results demonstrate that water deficit favors cell wall degradability and that breeding of varieties that reconcile improved drought-tolerance and biomass degradability is possible

Subtilase-mediated biogenesis of the expanded family of SERINE RICH ENDOGENOUS PEPTIDES

Plant signalling peptides are typically released from larger precursors by proteolytic cleavage to regulate plant growth, development and stress responses. Recent studies reported the characterization of a divergent family of Brassicaceae-specific peptides, SERINE RICH ENDOGENOUS PEPTIDES (SCOOPs), and their perception by the leucine-rich repeat receptor kinase MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2 (MIK2). Here, we reveal that the SCOOP family is highly expanded, containing at least 50 members in the Columbia-0 reference Arabidopsis thaliana genome. Notably, perception of these peptides is strictly MIK2-dependent. How bioactive SCOOP peptides are produced, and to what extent their perception is responsible for the multiple physiological roles associated with MIK2 are currently unclear. Using N-terminomics, we validate the N-terminal cleavage site of representative PROSCOOPs. The cleavage sites are determined by conserved motifs upstream of the minimal SCOOP bioactive epitope. We identified subtilases necessary and sufficient to process PROSCOOP peptides at conserved cleavage motifs. Mutation of these subtilases, or their recognition motifs, suppressed PROSCOOP cleavage and associated overexpression phenotypes. Furthermore, we show that higher-order mutants of these subtilases show phenotypes reminiscent of mik2 null mutant plants, consistent with impaired PROSCOOP biogenesis, and demonstrating biological relevance of SCOOP perception by MIK2. Together, this work provides insights into the molecular mechanisms underlying the functions of the recently identified SCOOP peptides and their receptor MIK2

Comparative transcriptomics of drought responses in Populus: a meta-analysis of genome-wide expression profiling in mature leaves and root apices across two genotypes

<p>Abstract</p> <p>Background</p> <p>Comparative genomics has emerged as a promising means of unravelling the molecular networks underlying complex traits such as drought tolerance. Here we assess the genotype-dependent component of the drought-induced transcriptome response in two poplar genotypes differing in drought tolerance. Drought-induced responses were analysed in leaves and root apices and were compared with available transcriptome data from other <it>Populus </it>species.</p> <p>Results</p> <p>Using a multi-species designed microarray, a genomic DNA-based selection of probesets provided an unambiguous between-genotype comparison. Analyses of functional group enrichment enabled the extraction of processes physiologically relevant to drought response. The drought-driven changes in gene expression occurring in root apices were consistent across treatments and genotypes. For mature leaves, the transcriptome response varied weakly but in accordance with the duration of water deficit. A differential clustering algorithm revealed similar and divergent gene co-expression patterns among the two genotypes. Since moderate stress levels induced similar physiological responses in both genotypes, the genotype-dependent transcriptional responses could be considered as intrinsic divergences in genome functioning. Our meta-analysis detected several candidate genes and processes that are differentially regulated in root and leaf, potentially under developmental control, and preferentially involved in early and long-term responses to drought.</p> <p>Conclusions</p> <p>In poplar, the well-known drought-induced activation of sensing and signalling cascades was specific to the early response in leaves but was found to be general in root apices. Comparing our results to what is known in arabidopsis, we found that transcriptional remodelling included signalling and a response to energy deficit in roots in parallel with transcriptional indices of hampered assimilation in leaves, particularly in the drought-sensitive poplar genotype.</p

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Energy values of registered corn forage hybrids in France over the last 20 years rose in a context of maintained yield increase

The cultivation of corn silage has developed in France since the 1970s to reach 1.5 million of hectares nowadays. Since 1998, a feeding value criterion (namely UFL for “Unité Fourrage Laitière”) has been taken into account to register forage varieties in the French forage maize hybrids catalog in addition to other criteria related to plant agronomical performances such as yield, earliness and lodging resistance. It is frequently stated that the improvement of plant’s agronomic performances would led to a decline in forage energy value. Decline of “Unité Fourrage Laitière” values has been repeatedly reported and the expected increase was not yet visible in 2002. In the present study, a set 47 early and mid-early hybrids commercialized in France between 1958 and 2015 has been cultivated in 3 locations in France. “Unité Fourrage Laitière” values and yield have been estimated in order to shed light on the evolution of feeding value criteria during this period and to conclude on the evolution of “Unité Fourrage Laitière” values since the introduction of this criterion for registration. Results obtained in our study demonstrated a recent rise in “Unité Fourrage Laitière” value in a context of strong yield increase. This increase was not necessarily attributable to high cob proportion in the harvested silage. Breeder’s work since the 2000’s has succeeded to offer hybrids that recover “Unité Fourrage Laitière” values similar to the ones of hybrids from the 1960’s (Royal, 1960, 91 UFL/100 kg DM). We propose to accentuate this effort targeting the enhancement of lignocellulosic cell wall digestibility to breed for future forage maize hybrids

Tissue lignification, cell wall <em>p</em>-coumaroylation and degradability of maize stems depend on water status

International audienceWater supply and valorization are two urgent issues in the utilization of maize biomass in the context of climate change and replacement of fossil resources. Maximizing maize biomass valorization is of interest to make biofuel conversion competitive, and to increase forage energetic value for animal fodder. One way to estimate biomass valorization is to quantify cell wall degradability. In this study, we evaluated the impact of water supply on cell wall degradability, cell wall contents and structure, and distribution of lignified cell types in maize internodes using dedicated high-throughput tools to effectively phenotype maize internodes from 11 inbred lines under two contrasting irrigation scenarios in field trials over three years. Overall, our results clearly showed that water deficit induced significant changes in lignin content and distribution along with a reduction in lignin p-coumaroylation, thereby impacting cell wall degradability. Additionally, we also observed that responses to a water deficit vaned between the lines examined, underscoring biochemical and histological target traits for plant breeding