Physiological and genetic control of transpiration efficiency in African rice, Oryza glaberrima Steud

Improving crop water use efficiency, the amount of carbon assimilated as biomass per unit of water used by a plant, is of major importance as water for agriculture becomes scarcer. In rice, the genetic bases of transpiration efficiency, the derivation of water use efficiency at the whole-plant scale, and its putative component trait transpiration restriction under high evaporative demand remain unknown. These traits were measured in 2019 in a panel of 147 African rice (Oryza glaberrima) genotypes known to be potential sources of tolerance genes to biotic and abiotic stresses. Our results reveal that higher transpiration efficiency is associated with transpiration restriction in African rice. Detailed measurements in a subset of highly contrasted genotypes in terms of biomass accumulation and transpiration confirmed these associations and suggested that root to shoot ratio played an important role in transpiration restriction. Genome wide association studies identified marker-trait associations for transpiration response to evaporative demand, transpiration efficiency, and its residuals, with links to genes involved in water transport and cell wall patterning. Our data suggest that root-shoot partitioning is an important component of transpiration restriction that has a positive effect on transpiration efficiency in African rice. Both traits are heritable and define targets for breeding rice with improved water use strategies.This work was supported by the Institut de Recherche pour le Développement, the CGIAR Research Program (CRP) on rice-agrifood systems (RICE, 2017-2022) and the Agence Nationale de la Recherche (grant ANR-17-MPGA-0011 to VV). Financial support by the Access to Research Infrastructures activity in the Horizon 2020 Programme of the EU (EPPN2020 Grant Agreement 731013) is gratefully acknowledged. PA was supported by a doctoral fellowship from the French Ministry of Higher Education. BEE was supported by the Centre National de la Recherche Scientifique et Technologique of Gabon. The authors acknowledge the IRD iTrop HPC (South Green Platform) at IRD Montpellier for providing HPC resources (https://bioinfo.ird.fr, http://www.southgreen.fr)

Investigation of Chernobyl 4-th unit materials by gamma activation method

Isotope and element content the samples of Chornobyl 4-th wrecking unit materials (concrete fragments and lava-like materials) were investigated by γ-activation method using bremsstrahlung of the electron accelerator. The concentration of a number of nuclides (U-238, Cs-137, Sr-90, Ni-58, Zr-90 etc.) and their depth distribution into concrete were determined as well as the corresponding correlation ratio. The comparison of the obtained data with the structure-phase analysis results was carried out

Author Correction: A chickpea genetic variation map based on the sequencing of 3,366 genomes

In Extended Data Fig. 1 of this Article, the labels ‘Market class’ and ‘Biological status’ were inadvertently swapped. In the corresponding figure legend, “Track 1: Biological status; Track 2: Market class;” should have been “Track 1: Market class; Track 2: Biological status;”. The original Article has been corrected online

A western Sahara centre of domestication inferred from pearl millet genomes

There have been intense debates over the geographic origin of African crops and agriculture. Here, we used whole-genome sequencing data to infer the domestication origin of pearl millet (Cenchrus americanus). Our results supported an origin in western Sahara, and we dated the onset of cultivated pearl millet expansion in Africa to 4,900 years ago. We provided evidence that wild-to-crop gene flow increased cultivated genetic diversity leading to diversity hotspots in western and eastern Sahel and adaptive introgression of 15 genomic regions. Our study reconciled genetic and archaeological data for one of the oldest African crops

Resequencing of 429 chickpea accessions from 45 countries provides insights into genome diversity, domestication and agronomic traits

We report a map of 4.97 million single-nucleotide polymorphisms of the chickpea from whole-genome resequencing of 429 lines sampled from 45 countries. We identified 122 candidate regions with 204 genes under selection during chickpea breeding. Our data suggest the Eastern Mediterranean as the primary center of origin and migration route of chickpea from the Mediterranean/Fertile Crescent to Central Asia, and probably in parallel from Central Asia to East Africa (Ethiopia) and South Asia (India). Genome-wide association studies identified 262 markers and several candidate genes for 13 traits. Our study establishes a foundation for large-scale characterization of germplasm and population genomics, and a resource for trait dissection, accelerating genetic gains in future chickpea breeding

Nucleotide diversity of genes involved in sucrose metabolism. Towards the identification of candidates genes controlling sucrosse variability in Coffea sp.

Quality and drought stress tolerance are two important targets for Coffea species cultivation. Currently, efficient genetic improvement of these traits is still hampered by the lack of early and cheap predictors. In this context, identification of molecular tools linked to these traits would significantly improve breeding efficiency. Based on the available literature, different metabolisms involved in the variability of both drought tolerance and coffee quality can be proposed. Based on this information, a study was initiated in Coffea species, aiming at estimating nucleotide diversity of four sucrose metabolism enzymes (Sucrose Synthase, Cell Wall Invertase, acid Vacuolar Invertase and Sucrose Phosphate Synthase). The two mains objectives of this work were i) to assess the level of variability of these genes within the whole area of distribution of Coffea canephora, and within 15 related Coffea species representing the four groups of diversity of this genus, and ii) to identify polymorphisms useful for mapping and association genetic studies. Almost 200 polymorphisms (SNP, INDELS, SSR) were identified through sequencing of Coffea canephora genotypes. In addition, analysis of the variability of these genes between different Coffea species allowed the identification of 300 additional polymorphic sites. Parallel in-silico analysis of EST resources confirmed the interest of this approach towards the identification of polymorphisms in Coffea sp. Identification of nucleotide polymorphisms will not only provide useful markers for traditional genetic studies (genetic mapping, population genetics, association studie) but also provide criteria to infer the evolutionary history of the analysed genes. Such information will be particularly relevant to select the best candidate genes to test in future association studies