Transition From Targeted Breeding to Mainstreaming of Biofortification Traits in Crop Improvement Programs.

Biofortification breeding for three important micronutrients for human health, namely, iron (Fe), zinc (Zn), and provitamin A (PVA), has gained momentum in recent years. HarvestPlus, along with its global consortium partners, enhances Fe, Zn, and PVA in staple crops. The strategic and applied research by HarvestPlus is driven by product-based impact pathway that integrates crop breeding, nutrition research, impact assessment, advocacy, and communication to implement country-specific crop delivery plans. Targeted breeding has resulted in 393 biofortified crop varieties by the end of 2020, which have been released or are in testing in 63 countries, potentially benefitting more than 48 million people. Nevertheless, to reach more than a billion people by 2030, future breeding lines that are being distributed by Consultative Group on International Agricultural Research (CGIAR) centers and submitted by National Agricultural Research System (NARS) to varietal release committees should be biofortified. It is envisaged that the mainstreaming of biofortification traits will be driven by high-throughput micronutrient phenotyping, genomic selection coupled with speed breeding for accelerating genetic gains. It is noteworthy that targeted breeding gradually leads to mainstreaming, as the latter capitalizes on the progress made in the former. Efficacy studies have revealed the nutritional significance of Fe, Zn, and PVA biofortified varieties over non-biofortified ones. Mainstreaming will ensure the integration of biofortified traits into competitive varieties and hybrids developed by private and public sectors. The mainstreaming strategy has just been initiated in select CGIAR centers, namely, International Maize and Wheat Improvement Center (CIMMYT), International Rice Research Institute (IRRI), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), International Institute of Tropical Agriculture (IITA), and International Center for Tropical Agriculture (CIAT). This review will present the key successes of targeted breeding and its relevance to the mainstreaming approaches to achieve scaling of biofortification to billions sustainably.

Availability, production, and consumption of crops biofortified by plant breeding: current evidence and future potential.

Biofortification is the process of increasing the density of vitamins and minerals in a crop through plant breeding-using either conventional methods or genetic engineering-or through agronomic practices. Over the past 15 years, conventional breeding efforts have resulted in the development of varieties of several staple food crops with significant levels of the three micronutrients most limiting in diets: zinc, iron, and vitamin A. More than 15 million people in developing countries now grow and consume biofortified crops. Evidence from nutrition research shows that biofortified varieties provide considerable amounts of bioavailable micronutrients, and consumption of these varieties can improve micronutrient deficiency status among target populations. Farmer adoption and consumer acceptance research shows that farmers and consumers like the various production and consumption characteristics of biofortified varieties, as much as (if not more than) popular conventional varieties, even in the absence of nutritional information. Further development and delivery of these micronutrient-rich varieties can potentially reduce hidden hunger, especially in rural populations whose diets rely on staple food crops. Future work includes strengthening the supply of and the demand for biofortified staple food crops and facilitating targeted investment to those crop-country combinations that have the highest potential nutritional impact.

An energy-dispersive X-ray fluorescence method for analyzing Fe and Zn in common bean, maize and cowpea biofortification programs.

BACKGROUND AND AIMS: Biofortification breeding programs have the need for rapid and accurate screening methods to identify nutrient dense genotypes. This study explores the use of energy dispersive x-ray fluorescence (EDXRF) for the rapid screening of iron (Fe) and zinc (Zn) concentration in three coarse-grain crops; common bean, maize and cowpea. METHODS: Bean, maize and cowpea seed was provided from biofortification breeding programs and analysed with Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) to determine reference Fe and Zn concentrations. A subset of samples for each crop was used to calibrate for Zn and Fe and a separate set of samples used to validate the XRF method. RESULTS: Results indicate that when analysing bean, maize and cowpea flour samples, the EDXRF results were not significantly different to the reference ICP-MS analysis, with an average difference of ± 1 mg kg-1 for both Fe and Zn. CONCLUSION: EDXRF analysis of common beans, cowpea and maize flour enables rapid and accurate analysis when screening for Fe and Zn in bean, maize and cowpea.

Extent and structure of genetic diversity in a collection of the tropical multipurpose shrub legume Cratylia argentea (Desv.) O. Kuntze as revealed by RAPD markers

The tropical multipurpose shrub legume Cratylia argentea is well adapted to acid soils of low to medium fertility and has excellent drought-tolerance. Due to its high nutritive value it is particularly suited as forage for dry-season supplementation. A collection of 47 C. argentea accessions in a collection, derived from seed replicating of original accessions with differing geographic origin and morphological and agronomic characteristics was investigated using molecular markers (RAPD (random amplified polymorphic DNA)). Genetic diversity (H T = 0.145) in the collection was low, with 30% of differentiation among groups and high genetic similarity among accessions (GS = 0.805). Within-accession variability was high. One taxonomic mismatch and five possible duplicate accessions were identified. Our results suggest that the genetic diversity in the C. argentea accessions studied is relatively homogeneously distributed, indicating the likelihood of extensive outcrossing. The genetic diversity of original accessions should be assessed to determine if outcrossing has occurred during or before ex situ storage. This might also support any decision on whether accessions should be bulked rather than maintaining them individually.