Moving towards grapevine genotypes better adapted to abiotic constraints

Vitis spp., both in their cultivated and wild forms, have been growing in a large diversity of environments for thousands of years. As a result, they have developed many adaptive mechanisms controlled by a range of regulatory processes. The cultivated species, Vitis vinifera, is quite well adapted to semi-arid conditions and its cultivation can be used to produce crops on marginal lands. However, this is threatened by climate change, which is associated with increased temperature and CO2 atmospheric content, changes in water availability and an increased likelihood of extreme events, such as heat waves and early spring frosts. Indirect effects of climate change on solar radiation and soil minerals are also expected. Consequently, cultivated grapevines will presumably face more abiotic constraints occurring concomitantly or successively over one or more growing cycles. In addition to climate change, worldwide viticulture must reduce the use of pesticides. Adapting to climate change and reducing pesticide use are challenging, and increase the need to create new grapevine varieties that are more resistant to diseases and better adapted to abiotic constraints. For this purpose, the adaptive mechanisms of wild and cultivated Vitis spp. must be exploited. While major advances have already been made in exploiting wild alleles for disease resistance, the polygenic nature of adaptation to abiotic factors has slowed down research progress. To tackle this limitation, ambitious integrative strategies need to be undertaken from collection and characterization of genetic resources, investigations on genetic architecture and identification of underlying genes (including those involved in epigenetic regulation), to the implementation of new breeding technologies and the development of genomic selection. An update on the state-of-the-art regarding these aspects is presented

Upregulation of HLA-E by dengue and not Zika viruses

Introduction: The most severe form of dengue virus (DENV) illness, dengue haemorrhagic fever, is characterised by plasma leakage and increased vascular permeability. Objectives: Given the critical role that endothelial cells play in the pathogenesis of DENV, we wanted to determine whether infection with DENV altered the expression of MHC class I related genes including HLA-E. Results: In this study, we provide evidence that HLA-E but not MICA/B or HLA-G is upregulated by all four serotypes of DENV in an endothelial cell line human microvascular endothelial cells (HMEC)-1. In contrast, Zika virus (ZIKV), a related flavivirus, where plasma leakage is not a major manifestation of disease, did not upregulate HLA-E. We found modest levels of soluble HLA-E in supernatants from DENV but not ZIKV-infected cells. Coculture experiments found minimal activation of natural killer (NK) cells in the presence of both uninfected and infected HMEC-1 cells. HLA-E induced by DENV infection could not dampen the degranulation of activated NK cells by interacting with its ligand NKG2a. Conclusions: Our results suggest that while DENV infection induces HLA-E, the high MHC class I expression on uninfected and infected HMEC-1 cells may dominate the diverse signals generated between inhibitory and activating receptors on NK cells and ligands on target cells

Countering elevated CO2 induced Fe and Zn reduction in Arabidopsis seeds

Growth at increased concentrations of CO2 induces a reduction in seed zinc (Zn) and iron (Fe). Using Arabidopsis thaliana, we investigated whether this could be mitigated by reducing the elevated CO2-induced decrease in transpiration. We used an infrared imaging-based screen to isolate mutants in At1g08080 that encodes ALPHA CARBONIC ANHYDRASE 7 (ACA7). aca7 mutant alleles display wild-type (WT) responses to abscisic acid (ABA) and light but are compromised in their response to elevated CO2. ACA7 is expressed in guard cells. When aca7 mutants are grown at 1000 ppm CO2 they exhibit higher transpiration and higher seed Fe and Zn content than WT grown under the same conditions. Our data show that by increasing transpiration it is possible to partially mitigate the reduction in seed Fe and Zn content when Arabidopsis is grown at elevated CO2

The subpolar gyre regulates silicate concentrations in the North Atlantic

publishedVersio

Multi-scale high-throughput phenotyping of apple architectural and functional traits in orchard reveals genotypic variability under contrasted watering regimes

Despite previous reports on the genotypic variation of architectural and functional traits in fruit trees, phenotyping large populations in the field remains challenging. In this study, we used high-throughput phenotyping methods on an apple tree core-collection (1000 individuals) grown under contrasted watering regimes. First, architectural phenotyping was achieved using T-LiDAR scans for estimating convex and alpha hull volumes and the silhouette to total leaf area ratio (STAR). Second, a semi-empirical index (IPL) was computed from chlorophyll fluorescence measurements, as a proxy for leaf photosynthesis. Last, thermal infrared and multispectral airborne imaging was used for computing canopy temperature variations, water deficit, and vegetation indices. All traits estimated by these methods were compared to low-throughput in planta measurements. Vegetation indices and alpha hull volumes were significantly correlated with tree leaf area and trunk cross sectional area, while IPL values showed strong correlations with photosynthesis measurements collected on an independent leaf dataset. By contrast, correlations between stomatal conductance and canopy temperature estimated from airborne images were lower, emphasizing discrepancies across measurement scales. High heritability values were obtained for almost all the traits except leaf photosynthesis, likely due to large intra-tree variation. Genotypic means were used in a clustering procedure that defined six classes of architectural and functional combinations. Differences between groups showed several combinations between architectural and functional traits, suggesting independent genetic controls. This study demonstrates the feasibility and relevance of combining multi-scale high-throughput methods and paves the way to explore the genetic bases of architectural and functional variations in woody crops in field conditions

Genetic and environmental dissection of biomass accumulation in multi-genotype maize canopies

International audienceMulti-genotype canopies are frequent in phenotyping experiments and are of increasing interest in agriculture. Radiation interception efficiency (RIE) and radiation use efficiency (RUE) have low heritabilities in such canopies. We propose a revised Monteith equation that identifies environmental and genetic components of RIE and RUE. An environmental term, a component of RIE, characterizes the effect of the presence or absence of neighbours on light interception. The ability of a given plant to compete with its neighbours is then identified, which accounts for the genetic variability of RIE of plants having similar leaf areas. This method was used in three experiments in a phenotyping platform with 765 plants of 255 maize hybrids. As expected, the heritability of the environmental term was near zero, whereas that of the competitiveness term increased with phenological stage, resulting in the identification of quantitative trait loci. In the same way, RUE was dissected as an effect of intercepted light and a genetic term. This approach was used for predicting the behaviour of individual genotypes in virtual multi-genotype canopies. A large effect of competitiveness was observed in multi-genotype but not in single-genotype canopies, resulting in a bias for genotype comparisons in breeding fields

Photosynthetic pigments of oceanic chlorophyta belonging to prasinophytes clade VII

Preprin

Plant phenomics, from sensors to knowledge

Major improvements in crop yield are needed to keep pace with population growth and climate change. While plant breeding efforts have greatly benefited from advances in genomics, profiling the crop phenome (i.e., the structure and function of plants) associated with allelic variants and environments remains a major technical bottleneck. Here, we review the conceptual and technical challenges facing plant phenomics. We first discuss how, given plants’ high levels of morphological plasticity, crop phenomics presents distinct challenges compared with studies in animals. Next, we present strategies for multi-scale phenomics, and describe how major improvements in imaging, sensor technologies and data analysis are now making high-throughput root, shoot, whole-plant and canopy phenomic studies possible. We then suggest that research in this area is entering a new stage of development, in which phenomic pipelines can help researchers transform large numbers of images and sensor data into knowledge, necessitating novel methods of data handling and modelling. Collectively, these innovations are helping accelerate the selection of the next generation of crops more sustainable and resilient to climate change, and whose benefits promise to scale from physiology to breeding and to deliver real world impact for ongoing global food security efforts

Dystrophin conferral using human endothelium expressing HLA-E in the non-immunosuppressive murine model of Duchenne muscular dystrophy

Human leukocyte antigen (HLA)-E is a non-classical major histocompatibility complex class I (Ib) molecule, which plays an important role in immunosuppression. In this study, we investigated the immunomodulating effect of HLA-E in a xenogeneic system, using human placental artery-derived endothelial (hPAE) cells expressing HLA-E in a mouse model. In vitro cell lysis analysis by primed lymphocytes in combination with siRNA transfection showed that HLA-E is necessary for inhibition of the immune response. Similarly, in vivo cell implantation analysis with siRNA-mediated down-regulation of HLA-E demonstrates that HLA-E is involved in immunosuppression. As hPAE cells efficiently transdifferentiate into myoblasts/myocytes in vitro, we transplanted the cells into mdx mice, a model of Duchenne muscular dystrophy. hPAE cells conferred dystrophin to myocytes of the ‘immunocompetent' mdx mice with extremely high efficiency. These findings suggest that HLA-E-expressing cells with a myogenic potential represent a promising source for cell-based therapy of patients with muscular dystrophy

Actin filament reorganisation controlled by the SCAR/WAVE complex mediates stomatal response to darkness.

This is the final version of the article. Available from the publisher via the DOI in this record.Stomata respond to darkness by closing to prevent excessive water loss during the night. Although the reorganisation of actin filaments during stomatal closure is documented, the underlying mechanisms responsible for dark-induced cytoskeletal arrangement remain largely unknown. We used genetic, physiological and cell biological approaches to show that reorganisation of the actin cytoskeleton is required for dark-induced stomatal closure. The opal5 mutant does not close in response to darkness but exhibits wild-type (WT) behaviour when exposed to abscisic acid (ABA) or CaCl2 . The mutation was mapped to At5g18410, encoding the PIR/SRA1/KLK subunit of the ArabidopsisSCAR/WAVE complex. Stomata of an independent allele of the PIR gene (Atpir-1) showed reduced sensitivity to darkness and F1 progenies of the cross between opal5 and Atpir-1 displayed distorted leaf trichomes, suggesting that the two mutants are allelic. Darkness induced changes in the extent of actin filament bundling in WT. These were abolished in opal5. Disruption of filamentous actin using latrunculin B or cytochalasin D restored wild-type stomatal sensitivity to darkness in opal5. Our findings suggest that the stomatal response to darkness is mediated by reorganisation of guard cell actin filaments, a process that is finely tuned by the conserved SCAR/WAVE-Arp2/3 actin regulatory module.This work was supported by grants from the BBSRC (BB/ N001168/1; BB/J002364/1; BBF001177/1), The Gatsby Charitable Foundation and the Leverhulme Trust to A.M.H. and grants from the National Natural Science Foundation of China (nos. 31300213 and 31670408 to K.J.). This work was also supported by the Centre National de la Recherche Scientifique and the Commissariat a l’Energie Atomique et aux Energies Alternatives (for the IR camera) and the European Union Marie Curie FP5 Research Training Network (program no. STRESSIMAGING HNRT-CT-2002-00254 to J.M.C. and B.G.). J.M.C. was in addition supported by a scholarship of the Fundac ~ao para a Ci^encia e Tecnologia, Portugal (grant no. SFRH/BPD/34429/2006)