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USAID-Feed the Future Innovation Lab – Development of Abiotic Stress Tolerant Millet for Africa and South Asia

USAID-Feed the Future Innovation Lab – Development of Abiotic Stress Tolerant Millet for Africa and South Asia

Millet plays different roles in food security. It remains a staple food for millions among the poorest in both India and Africa. At the same time, its growing value in the food and feed industry offers opportunities for income generation. This economic value is evident from the growth in production in both regions, even if the acreage has declined. While among the staples most adapted to harsh environments, productivity gains from increased and broad stress tolerance will be significant. The stability of yields in the marginal environments that typify millet production is particularly important for the poor who depend upon this crop.

This partnership will bring together proprietary resources and technical expertise to make significant gains in millet yields by harnessing a combination of stress tolerant germplasm with several transgenic traits. The goal that will extend beyond the life of this grant is to pyramid these traits through breeding in combinations that will substantially increase yields over current elite hybrids and non-hybrid varieties grown by small resource poor farmers. We will characterize a recently identified stress tolerant QTL through fine mapping and metabolomics so as to identify the basis for tolerance and optimize synergies with the stress response pathway mediated by one of the transgenes, sark-IPT. By the end of the project, we will generate four new transgenic lines and initiate field trials on these at two locations in India. Greenhouse and field testing will be conducted in parallel by both ICRISAT and Krishidhan Seeds. Arcadia Biosciences will provide technical support to both partners in screening protocols for both greenhouse and field trials and oversee the stewardship of the transgenic materials.

The technical objectives of this proposal are:

UC Davis will express PSARK::IPT in pearl millet (Pennisetumglaucum L.) and generate marker free transgenic plants. In addition to this drought-tolerant trait, plants will be transformed to express three other genes, NHX, which has been shown to confer salt tolerance, and HSR1 and SOD, that have been shown to confer heat-tolerance. Transformed plants expressing each trait and a combination of all traits will be genotyped and phenotyped in greenhouses at UC Davis for combinations of drought, salinity, and heat, a strategy of terminal drought that most closely resembles field conditions where these stresses are interlinked.

ICRISAT will refine the molecular mapping of the terminal drought tolerance QTL in pearl millet and of the traits that are likely related to that QTL. This QTL reflects the capacity of terminal drought tolerant lines to limit leaf conductance under non-stress conditions, therefore saving water for the later stage of grain filling [1, 2]. Through fine mapping, near isogenic lines (NIL) containing individual QTLs for leaf conductance will be developed and tested. We will develop these NIL together with a downy mildew resistance (DMR), which is essential for the target region. In addition, the mapping of water saving traits will be carried out in another recombinant inbred line population segregating for these traits.

Transgenic pearl millet lines displaying enhanced stress-tolerance in the greenhouse at UC Davis will be transferred to ICRISAT and UCD for further greenhouse and field testing. To avoid inbreeding depression, all materials will be tested in the form of top-cross hybrid using male-sterile downy mildew resistant 843A line. A range of water stress conditions will be used to choose best candidate material for specific drought scenarios.

Introgression lines of the terminal drought tolerance QTL, and NILs containing leaf conductance QTLs will be further characterized at UC Davis using a Systems Biology approach that will combine genomics, proteomics and metabolomics in order to identify key candidate genes and characterize metabolic networks associated with enhanced drought resistance and their association with the cytokinin-mediated pathways.