Accelerating simultaneous genetic gain in wheat for grain yield and other relevant traits to enhance productivity, nutrition, and farmers income Abstract uri icon

abstract

  • The global wheat yield has increased annually at a pace of >1% annually in the past 60 years. Because productivity gains in various regions are predicted to be negatively impacted from climate change, accelerating the rate of yield genetic gain in combination with other relevant production and nutrition traits is a viable strategy for delivering more productive varieties capable of offsetting the negative climate change effects. To achieve this CIMMYT wheat breeding program is in the process of adopting the following changes: a) establishment of product profiles based breeding pipelines targeting five major spring wheat production environments of Asia, Africa and Latin America; b) implementation of “Rapid Bulk Generation Advancement” (RBGA) and yield testing schemes to complete a breeding cycle in 3-years; c) expansion of stage 2 yield testing by National partner networks within each target population of environments (TPEs) for a faster identification and access of adapted parents and products; d) genomic selection (GS) at pre-stage 1 yield testing to cull lines with low genomic estimated breeding values (GEBVs); and e) improved utilization and sharing of phenotypic and genotypic data, and parental recycling using breeding values and selection indices. RBGA is a low-cost scheme where generation of new crosses, and advancement of F1 and F2 bulks will be completed within a year. In year 2, F3 populations will be sown in field to select individual plants for agronomic traits and disease resistance, and harvested spikes for grain traits before sowing F4 head-rows plots in the field for the 2nd round of selection. In year 3, further phenotyping/seed multiplication/genotyping/GS conducted simultaneously for promoting best lines to expanded stage 1 yield phenotyping in diverse, well managed selection environments (SEs) for yield potential, drought, and heat tolerance to identify the best set of lines for stage 2 testing and parents for recycling. The RBGA scheme uses the same shuttle breeding field sites in Mexico, i.e., Ciudad Obregon and Toluca/El Batan, respectively to enable growing two crop seasons per year. Speed-breeding facility is used for a fast advancement of F1. Durable resistance, conferred by combinations of multiple intermediate to small effect genes, remains central to offset faster evolution and migration of virulent races of rusts, spot blotch, wheat blast, and other fungi. A continuous monitoring for pathogen populations, resistance phenotyping, and diversity enhancement for genes involved in resistance durability are essential. We have also established a trait-integration pipeline to incorporate new genes/QTL in high value elite varieties and parents, and disease phenotyping platforms, e.g., Kenya for stem rust/yellow rust, Bangladesh, and Bolivia for wheat blast, will continue to strengthen resistance breeding. In addition to end-use quality, mainstreaming of high grain zinc and iron, for which good progress and genetic diversity now exists in high yielding parents, was also initiated. These changes are expected to deliver higher rates of genetic gain in farmer’s field by simultaneously implementing strategies to encourage faster variety turnover.

publication date

  • September 2022