Contributions

CoA 5.2 Trait discovery

Breeders from partner Centers have consolidated their expert opinion and published reports by crop/country or the major productivity traits and quality traits required to address farmer and consumer demands. This CoA will emphasize on traits prioritized (Table FP4.2) from surveys and focus group discussions in the Phase I programs, DC and GL, and on newer priorities identified through FP1, and feedback from FP2. CoA5.2 will focus on understanding the genetic, physiological and biochemical mechanisms of traits; identification of diagnostic molecular markers and functional validations of candidate genes associated with these traits; and development of novel breeding approaches for enhancing yield potential for GLDC crops. Some of the research areas (e.g., exploitation of the germplasm of cultivated species for pod borer resistance, resistance to aflatoxin contamination and low P tolerance in legumes; cold tolerance in sorghum) have been deprioritized in CoA5.2 because of limited or lack of genetic variability in the existing germplasm and/or due to change in priorities (refs). The focus will be on key traits such as nutrient-use efficiency for ESA, WCA, or by using alternative approaches through genetic engineering, host-induced gene silencing (HIGS) and genome editing under CoAs 5.1 and 5.3. In the initial phase of GLDC, research will continue on ‘no regret’ or key important traits, while a systematic trait prioritization exercise will be undertaken by FP1 which will enable FP5 to focus on specific traits based on future market demands. The summary of prioritized traits (including 'no regret traits'), besides yield enhancement as a common trait for crops/regions are presented in Table FP4.2.

While at the plant level, agronomic traits include grain yield, nutrient-use efficiency, nitrogen fixation, and phenology, at the crop and system level, traits such as plant architecture (for intercropping), residue quantity and quality (for livestock; contribution to soil cover and organic matter), and ability to establish in harsh environments (creating a good plant stand) are equally important. Yield enhancement will remain an important trait as long as the untapped genetic potential of these crops offer opportunities, especially for yield gains in low input situations. Research will also focus on early maturity and plant stature that allow possibilities for machine harvesting, especially in chickpea and lentil. While nitrogen fixation traits will be important for the legumes, nutrient-use efficiency and herbicide tolerance will be important for all GLDC crops. Further evaluations will explore the potential of legume germplasm for capacities to fix N symbiotically, especially under conditions of water limitation or low soil P availability.

Key abiotic stresses that adversely affect production of GLDC crops like drought and heat will be closely linked to the use of crop simulation analysis (FP4 CoA4.1) to guide the search for genetic alterations potentially contributing to increased crop performance under water limitation, besides potential trade-offs with some of these traits. The physiological mechanisms of drought tolerance in relation to water economy will be addressed by high-throughput phenotyping and well-characterized mapping populations²⁷³. Testing and identifying of germplasm and using molecular markers for drought and/or heat tolerance will be explored especially for chickpea, cowpea, lentil, groundnut, pearl millet and sorghum.

Disease resistance research in the target countries is prioritized based on the severity of yield losses, extent of disease prevalence, resistance sources available and regional demands. This CoA aims for better understanding of host plant resistance and diversity in resistance sources and the pathogens where the identification of diverse sources of resistance to diseases will be organized through evaluation of mini core collections as well as sampling procedures like “Focused Identification of Germplasm Strategy” (FIGS). Linked to CoA5.1, technologies like transgenics and host-induced gene silencing (HIGS) are being used for complex diseases in addition to phyto-sanitary and food safety issues such as pre-harvest A. flavus infection and resulting aflatoxin contamination. Supported by CRP and bilateral funding, efforts will be made to enhance understanding of new and emerging diseases, genetics and resistance mechanisms and molecular markers/candidate genes associated with disease resistance.

Insect pests of the target cereal crops include aphids, shoot fly, stem-borer and midges, while pod-borers (Helicoverpa armigera and Maruca vitrata), leaf miners, aphids and stored grain pests are the major insect-pests of legumes. Due to low or non-existence of resistance to pod borers in cultivated chickpea, cowpea and pigeonpea, screening of germplasm mini core collections and introgression of insect resistance from wild relatives will be undertaken as part of CoA5.1 and complemented by transgenic approaches where applicable. Yield losses from parasitic (Striga, Orobanche) and non-parasitic weeds are severe in both legumes and cereals. While breeding for resistance to Striga has been successful for sorghum and cowpea to some extent, efforts on the identification of molecular mechanisms of host-pathogen resistance are currently ongoing for identifying sustainable resistance to Striga through CoA5.3. For countries and regions where high-input agriculture is practiced, the combination of herbicides and herbicide-tolerant crop varieties will be explored through mutation breeding, as well as transgenic technologies in GLDC target crops amongst both CGIAR and non-CGIAR partners, and as guided by the ISPC’s strategy on biotechnology (ISPC 2014).

GLDC crops are highly valued for their nutrient-dense nature, and FP5 endeavors to ensure that their nutritional qualities are further enhanced in new varieties/hybrids. Key quality traits include protein content in legumes (oil quality in groundnut) and micronutrients (iron, zinc, calcium) in most crops. Existing collaborations with HarvestPlus in A4NH (for micronutrients on lentil, pearl millet and sorghum), the USAID Feed the Future Innovation Lab (for Peanut Productivity and Mycotoxin Control) and the University of Georgia and USDA Southern Regional Research Station, Louisiana (for research on aflatoxin in groundnut) will be further strengthened for testing of promising germplasm and identification of nutrient-dense germplasm lines. Fodder quality will be enhanced in collaboration with CRP-LIVESTOCK under “Full-purpose crops” through joint resource mobilization. While the initiatives have been taken towards identification of molecular markers for these quality traits, further understanding will be developed using targeted analysis of specific pathways and regulatory genes. Collaboration with ILRI and CRP-LIVESTOCK will provide access to grain and fodder-quality screening facilities such as Near-Infrared Spectroscopy (NIRS) and the X-Ray Fluorescence analyzer. The possibility of developing and using field-based NIRS for high-throughput fodder-quality analysis will be explored and extended to grain quality. In addition, certain consumer-preferred and market-pull traits such as longer shelf-life of pearl millet flour (affected by rancidity), high oil and aflatoxin-free groundnut will be addressed through various discovery approaches (Table FP4.2).