Does root plasticity contribute to crop tolerance to abiotic stresses?

Poster that presents the experiments, the main results and take home messages

Nitrogen use efficiency in bread wheat: breeding tools and recent genetic progress

International audienc

Phenotypic characterization of French elite germplasm in response to drought stress

International audienc

Genome-wide identification of chromosomal regions determining nitrogen use efficiency components in wheat

International audienc

A multi-environmental study of recent breeding progress on nitrogen use efficiency in wheat (<em>Triticum aestivum L.</em>)

International audienceBy comparing 195 varieties in eight trials, this study assesses nitrogen use efficiency improvement in high and low nitrogen conditions in European winter wheat over the last 25 years. In a context where European agriculture practices have to deal with environmental concerns and nitrogen (N) fertiliser cost, nitrogen use efficiency (NUE) has to be improved. This study assessed genetic progress in winter wheat (Triticum aestivum L.) NUE. Two hundred and twenty-five European elite varieties were tested in four environments under two levels of N. Global genetic progress was assessed on additive genetic values and on genotype x N interaction, covering 25 years of European breeding. To avoid sampling bias, quality, precocity and plant height were added as covariates in the analyses when needed. Genotype x environment interactions were highly significant for all the traits studied to such an extent that no additive genetic effect was detected on N uptake. Genotype x N interactions were significant for yield, grain protein content (GPC), N concentration in straw, N utilisation, and NUE. Grain yield improvement (+0.45 % year(-1)) was independent of the N treatment. GPC was stable, thus grain nitrogen yield was improved (+0.39 % year(-1)). Genetic progress on N harvest index (+0.12 % year(-1)) and on N concentration in straw (-0.52 % year(-1)) possibly revealed improvement in N remobilisation. There has been an improvement of NUE additive genetic value (+0.33 % year(-1)) linked to better N utilisation (+0.20 % year(-1)). Improved yield stability was detected as a significant improvement of NUE in low compared to high N conditions. The application of these results to breeding programs is discussed

QTL analyses for nitrogen use and grain protein in bread wheat

International audienc

Genetic regions determine tolerance to nitrogen deficiency in European elite bread wheats grown under contrasting nitrogen stress scenarios

Increasing the nitrogen use efciency of wheat varieties is an important goal for breeding. However, most genetic studies of wheat grown at diferent nitrogen levels in the feld report signifcant interactions with the genotype. The chromo somal regions possibly involved in these interactions are largely unknown. The objective of this study was to quantify the response of elite bread wheat cultivars to diferent nitrogen feld stress scenarios and identify genomic regions involved in this response. For this purpose, 212 elite bread wheat varieties were grown in a multi-environment trial at diferent nitrogen levels. Genomic regions associated with grain yield, protein concentration and grain protein deviation responses to nitrogen defciency were identifed. Environments were clustered according to adjusted means for grain yield, yield components and grain protein concentration. Four nitrogen availability scenarios were identifed: optimal condition, moderate early defciency, severe late defciency, and severe continuous defciency. A large range of tolerance to nitrogen defciency was observed among varieties, which were ranked diferently in diferent nitrogen defciency scenarios. The well-known nega tive correlation between grain yield and grain protein concentration also existed between their respective tolerance indices. Interestingly, the tolerance indices for grain yield and grain protein deviation were either null or weakly positive meaning that breeding for the two traits should be less difcult than expected. Twenty-two QTL regions were identifed for the tolerance indices. By selecting associated markers, these regions may be selected separately or combined to improve the tolerance to N defciency within a breeding programme

Genome-wide association of winter bread wheat (Triticum aestivum L.) response to drought in a multi-environment European network

International audienc

Using environmental clustering to identify specific drought tolerance qtls in bread wheat (<em>t. aestivum</em> l.)

International audienceDrought is one of the main abiotic stresses limiting winter bread wheat growth and productivity around the world. The acquisition of new high-yielding and stress-tolerant varieties is therefore necessary and requires improved understanding of the physiological and genetic bases of drought resistance. A panel of 210 elite European varieties was evaluated in 35 field trials. Grain yield and its components were scored in each trial. A crop model was then run with detailed climatic data and soil water status to assess the dynamics of water stress in each environment. Varieties were registered from 1992 to 2011, allowing us to test timewise genetic progress. Finally, a genome-wide association study (GWAS) was carried out using genotyping data from a 280 K SNP chip. The crop model simulation allowed us to group the environments into four water stress scenarios: an optimal condition with no water stress, a post-anthesis water stress, a moderate-anthesis water stress and a high pre-anthesis water stress. Compared to the optimal water condition, grain yield losses in the stressed conditions were 3.3%, 12.4% and 31.2%, respectively. This environmental clustering improved understanding of the effect of drought on grain yields and explained 20% of the G x E interaction. The greatest genetic progress was obtained in the optimal condition, mostly represented in France. The GWAS identified several QTLs, some of which were specific of the different water stress patterns. Our results make breeding for improved drought resistance to specific environmental scenarios easier and will facilitate genetic progress in future environments, i.e., water stress environments

Improving water use efficiency in wheat (Triticum aestivum L.) by multi-trait multi-environment genome-wide association studies

National audienc