Abstract only

The combined problems of climate change, population growth, and increased demands on a declining natural resource base, force scientists to push crop performance to its limits. A powerful strategy is to explore genetic resources under a range of contrasting environments to identify promising sources that can be used directly in breeding, for gene discovery, and to further understand the mechanisms of adaptation. For example, over 70,000 accessions of the World Wheat Collection housed at CIMMYT have been screened for adaptation to heat and drought stress -mostly for the first time-, and diverse panels have been assembled for association mapping. The best lines are used directly in pre-breeding. For example, earlier pilot studies identified Mexican landraces as sources of deep roots and the capacity for storage of stem water soluble carbohydrates; they are present in the pedigrees of a new generation of stress adapted lines distributed by CIMMYT international nurseries in 2009. Other more targeted approaches include characterization of panels identified using agro-geological data (Focused Identification of Germplasm Strategy): landraces from heat and drought stressed regions being likely source of resistance. Being a polyploid, wheat has a useful secondary gene pool that can be used to re-synthesize hexaploid wheat. Many thousands of accessions of both ancestral genomes (AB and D) exist as candidates for inter-specific hybridization. Physiological characterization is being used to help select the most promising accessions, as well as to select among the initial products (primary ?synthetics?), for pre-breeding and genetic studies. In parallel to this, genotyping of existing primary synthetics and potential progenitors (AB tetraploid, and Ae taushii) is being carried out to target under-utilized genetic diversity. Transgenic approaches remove all taxonomic limits to plant improvement. Biotechnology has provided the opportunity to manipulate transcription factors regulating a large number of genes associated to stress responses. As a result, promising genetically modified lines have been selected and performance under field conditions is being evaluated. To efficiently explore genetic resources -for crop improvement and to identify genetic and mechanistic bases- requires a combination of precision and high throughput phenotyping approaches. For example, the application of an airborne remote sensing platform (consisting of an unmanned aerial vehicle and a helium filled tethered blimp) is used to determine spectral indices associated with temperature, water content and pigment composition of leaves via thermal and multispectral imagery. Thousands of genetic resources in the field can be screened in one image, avoiding any temporal variation associated with larger trials, with still enough resolution to obtain information at plot level. Other approaches are being used to screen for heat tolerant metabolism including tools to estimate membrane thermo-stability such as electrolyte leakage and chlorophyll fluorescence. Next-generation phenotyping platforms will therefore help to identify from among thousands of genetic resources, those with the greatest promise to adapt new cultivars to warmer climates.

Global Wheat Program

English

Lucia Segura

INT1511|INT3468|INT3233|INT3189|INT2731

CIMMYT Staff Publications Collection