CRP Success Story: Mutation Breeding for Resistance to Striga Parasitic Weed in Cereals for Food Security (D25005)

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

Striga parasitic weeds are major biological constraints for cereal production and threats to food and nutritional security in sub-Saharan Africa and semi-arid tropical regions of Asia. Losses in crop yield due to Striga infestation are reported to be above 40% and may reach 100% under heavy infestations, especially in low-input farming areas. The Food and Agriculture Organization of the United Nations (FAO) estimates more than US$7 billion is lost due to Striga across Africa every year, adversely affecting over 300 million people on 50 million hectares of Striga infected crop lands. 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 Striga Parasitic Weed in Cereals for Food Security (D25005) targeted mutation breeding using physical mutagenesis for broadening resistance to Striga in sorghum, maize and upland rice. It focused on the development or adaptation of screening protocols for Striga resistance in the field, greenhouse and laboratories, and integration of efficiency enhancing technologies.

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

Develop, optimize and validate technology packages for screening of mutant populations for resistance to Striga in major cereals.

Integrate efficiency enhancing techniques for rapid generation of genetic diversity in major cereals (doubled haploid, rapid cycling & genomics).

Generate genetic diversity to develop resistant varieties to Striga infestation.

Enhance capacity in efficient mutation breeding for resistance to Striga in Member States.

The CRP has achieved these planned targets as shown by the following examples:

Three field, four greenhouse and six laboratory protocols were developed, validated and used by participating Member States to induce and characterize novel variation in the targeted crops (sorghum, maize and upland rice).

Efficiency enhancing technologies such as rapid generation cycling, doubled haploid, metabolomic and genomic are developed/adapted and used in the characterization of the identified mutants and acceleration of the breeding programme. Four to six generations of sorghum could be produced in one year, reducing the time to deliver advanced mutant lines in two years instead of five to seven years using the conventional approach.

64 induced mutants were identified with resistance/tolerance to S. hermonthica or asiatic in sorghum, maize and upland rice.

At least three of the verified mutants from each crop were advanced to field evaluation for possible release in three of the participating countries (Burkina Faso, Madagascar and Sudan) to ensure sustainable production under Striga prone fields.

Capacity building: In addition to targeted individual training within the context of the CRP for more than 20 individual fellows/interns at the Plant Breeding and Genetics Laboratory, six MSc and six PhD students conducted their studies in collaboration with participating Member States and the Plant Breeding and Genetics Laboratory.

The CRP was implemented by the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture using six research and two technical contracts, and four agreements. Five of the participating contract holders in the CRP were from Africa, three from Asia, two from Europe and two from USA.

An additional indication of the CRP’s success was that it generated 12 peer-reviewed publications and ten conference proceedings. Furthermore, additional papers are in the pipeline. A book compiling twelve chapters of the optimized protocols during the CRP is planned to be published under Springer Nature Open Access publications.

The CRP improved human capacity and the developed resistant mutant lines in the major cereals are expected to generate tangible impact on sustainable production and food security in Striga-prone areas in Africa and part of Asia. Experts involved in the project recommend the following for the best utilization of the results generated by the CRP:

Official release of resistant lines developed in sorghum, rice and maize through IAEA technical cooperation (TC) projects for wide use by farmers (BK5019, BKF2020005, MAD5025, MAD5026).

Support of a regional project (TC or specially funded) to test advanced resistant/tolerant lines in Striga-prone countries of Africa for their wide utilization.

Wide dissemination of technology packages for resistance screening developed by the CRP to affected Member States through TC projects to combat the devastating parasite.

Source: International Atomic Energy Agency