Mutation breeding for resistance to the parasitic weed Striga in cereals for food security (D25005)

A recently completed five-year Coordinated Research Project (CRP) (D25005) by the IAEA has helped experts from 12 countries identify new sources of resistance to the devastating parasitic weed Striga in cereals with effective protocols, which help them reduce production constraints and improve food safety.

Striga Parasitic weeds are major biological constraints on cereal production and threats to food and nutrition security in sub-Saharan Africa and in the semi-arid tropics of Asia. Crop yield losses due to Striga infestations are reported to be above 40% and can reach 100% in heavy infestations, especially in low-input agricultural areas. The Food and Agriculture Organization of the United Nations (FAO) estimates that more than US$7 billion is lost due to Striga across Africa each year, affecting more than 300 million people on 50 million hectares of Striga infected cropland. Host plant resistance is the most tangible control measure of Striga. This can be achieved through nuclear applications by inducing noble sources of genetic variation for the development of resistant varieties of vulnerable food crops.

The CRP on mutation breeding for resistance to weed parasitic striga in cereals for food security (D25005) targeted mutation breeding using physical mutagenesis to expand resistance to Striga in sorghum, maize and upland rice. It focused on the development or adaptation of screening protocols for Striga field, greenhouse and laboratory resistance, and the integration of efficiency-enhancing technologies.

The CRP attracted experts from 12 research teams from cereal improvement programs and Striga biologists from several countries. The overall objective of the CRP was to support the generation of new sources of variation, using mutation breeding, developing effective screening protocols for Striga resistance in cereals in order to improve food security in Member States. . To achieve this goal, the following four specific research objectives have been established:

  • Develop, optimize and validate technological packages for the screening of mutant populations for resistance to Striga in the main cereals.
  • Integrate efficiency-enhancing techniques for the rapid generation of genetic diversity in major cereals (doubled haploid, rapid cycling and genomics).
  • Generate genetic diversity to develop resistant varieties Striga infestation.
  • Improve the capacity for efficient mutation selection for resistance to Striga in the Member States.

The CRP has achieved these intended objectives, as the following examples show:

  • Three field, four greenhouse and six laboratory protocols were developed, validated and used by participating Member States to induce and characterize new variations in the target crops (sorghum, maize and upland rice).
  • Efficiency enhancing technologies such as rapid generation cycle, doubled haploid, metabolomics and genomics are developed/adapted and used in characterization of identified mutants and acceleration of breeding program. Four to six generations of sorghum could be produced in one year, reducing the time to produce advanced mutant lines to two years instead of five to seven years with the conventional approach.
  • 64 induced mutants were identified with resistance/tolerance to S.hermonthica Where Asian in sorghum, maize and upland rice.
  • At least three of the verified mutants from each culture have been subjected to field evaluation for possible release in three of the participating countries (Burkina Faso, Madagascar and Sudan) to ensure sustainable production under Striga subject fields.
  • Capacity Building: In addition to targeted individual training under the CRP for more than 20 individual fellows/trainees at the Plant Breeding and Genetics Laboratory, six MSc students and six PhD students conducted their studies in collaboration with Member States participants and the Plant Breeding Laboratory. and genetics laboratory.

The CRP was implemented by the Joint FAO/IAEA Center for Nuclear Techniques for Food and Agriculture through six research contracts and two technical contracts, and four agreements. Five of the policyholders participating in the CRP were from Africa, three from Asia, two from Europe and two from the United States.

A further indication of the success of the CRP is that it has generated 12 peer-reviewed publications and ten conference proceedings. In addition, other articles are in preparation. A book compiling twelve chapters of protocols optimized during CRP is expected to be published under Springer Nature Open Access Publications.

CRP has improved human capacities and the resistant mutant lines developed in major cereals should generate a tangible impact on sustainable production and food security in Striga– prone areas in Africa and part of Asia. The experts involved in the project recommend the following for better use of the results generated by the CRP:

  • Official launch of resistant lines developed in sorghum, rice and maize under IAEA Technical Cooperation (TC) projects for wide use by farmers (BK5019, BKF2020005, MAD5025, MAD5026).
  • Support for a regional project (TC or specially funded) to test advanced resistant/tolerant lines in Striga-African countries inclined for their wide use.
  • Wide dissemination of resistance screening technology packages developed by CRP to affected Member States through TC projects to combat the devastating parasite.