Genome-Wide Association Study of Nitrogen Use Efficiency and Agronomic Traits in Upland Rice

Genome-wide association study(GWAS)was performed for 16 agronomic traits including nitrogen use efficiency(NUE)and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38390 single nucleotide polymorphism(SNP)markers.This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels.Using another set of five grain traits,we identified previously known genes(GW5,GS3,Awn1 and Glabrous1),thus validating the pertinence and accuracy of our datasets for GWAS.A total of 369 significant associations were detected between SNPs and agronomic traits,gathered into 46 distinct haplotype groups and 28 isolated markers.Few association signals were identified for the complex quantitative trait NUE,however,larger number of quantitative trait loci(QTLs)were detected for its component traits,with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency,respectively.Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb.The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits.However,because of the quantitative and complex nature of NUE-related traits,GWAS might have not captured a large number of QTLs with limited effects.

ENABLING CROP DIVERSIFICATION TO SUPPORT TRANSITIONS TOWARD MORE SUSTAINABLE EUROPEAN AGRIFOOD SYSTEMS

European cropping systems are often characterized by short rotations or even monocropping,leading to environmental issues such as soil degradation,water eutrophication,and air pollution including greenhouse gas emissions,that contribute to climate change and biodiversity loss.The use of diversification practices(i.e.,intercropping,multiple cropping including cover cropping and rotation extension),may help enhance agrobiodiversity and deliver ecosystem services while developing new value chains.Despite its benefits,crop diversification is hindered by various technical,organizational,and institutional barriers along value chains(input industries,farms,trading and processing industries,retailers,and consumers)and within sociotechnical systems(policy,research,education,regulation and advisory).Six EU-funded research projects have joined forces to boost crop diversification by creating the European Crop Diversification Cluster(CDC).This Cluster aggregates research,innovation,commercial and citizen-focused partnerships to identify and remove barriers across the agrifood system and thus enables the uptake of diversification measures by all European value-chain stakeholders.The CDC will produce a typology of barriers,develop tools to accompany actors in their transition,harmonize the use of multicriteria assessment indicators,prepare policy recommendations and pave the way for a long-term network on crop diversification.