Prospects of breeding biofortified pearl millet with high grain iron and zinc content

Development of crop cultivars with elevated levels of micronutrients is being increasingly recognized as one of the approaches to provide sustainable solutions to various health problems associated with micronutrient malnutrition, especially in developing countries. To assess the prospects of this approach in pearl millet (Pennisetum glaucum), a diverse range of genetic materials, consisting of 40 hybrid parents, 30 each of population progenies and improved populations, and 20 germplasm accessions, was analysed for grain iron (Fe) and zinc (Zn) content, deficiencies of which adversely affect human health. Based on the mean performance in two seasons at ICRISAT, Patancheru, India, large variability among the entries was found, both for Fe (30.1–75.7 mg/kg on dry weight basis) and Zn (24.5– 64.8 mg/kg). The highest levels of grain Fe and Zn were observed in well-adapted commercial varieties and their progenies, and in the parental lines of hybrids, which were either entirely based on iniari germplasm, or had large components of it in their parentage. There were indications of large within-population genetic variability for both Fe and Zn. The correlation between Fe and Zn content was positive and highly significant (r ¼ 0.84; P < 0.01). These results indicate that there are good prospects of simultaneous selection for both micronutrients, and that selection within populations, especially those with the predominantly iniari germplasm, is likely to provide good opportunities for developing pearl millet varieties and hybrid parents with significantly improved grain Fe and Zn content in pearl millet. Micronutrient malnutrition, resulting from the dietary deficiency of some of the important minerals such as iron (Fe) and zinc (Zn), and vitamin A, has been reported to be a widespread foodrelated health problem, affecting more than two billion people worldwide (WHO 2002). This problem is particularly serious in developing countries where most of the population has limited access to meat, fruits and vegetables, which are generally rich sources of these micronutrients. The HarvestPlus initiative of the Consultative Group on International Agricultural Research (CGIAR) has recently embarked on addressing this issue through the development of improved crop cultivars with elevated levels of these micronutrients. Pearl millet [Pennisetum glaucum (L.) R. Br. ], grown on more than 26 million ha in the arid and semi-arid regions of Asia and Africa, and serving as a major source of dietary energy for a vast population in these regions, is one of the crops included in this initiative. A pearl millet breeding line with yellow grain colour derived from a germplasm accession originating from Burkina Faso, with b-carotene (precursor of vitamin A) levels as high as 137 lg/100 g has been identified at ICRISAT, Patancheru, India (Hash et al. 1996). Attempts are underway to identify molecular markers of the gene(s) associated with this trait and use molecular marker technology to transfer it into commercial open-pollinated varieties and hybrid parents. Pearl millet has high grain Fe and Zn content. There are reports of up to 580 mg/ kg Fe and 70 mg/kg Zn in pearl millet germplasm accessions (Jambunathan and Subramanian 1988), but neither the identity of these accessions is available, nor have the micronutrient analyses protocols been reported. The initial objective of the HarvestPlus project on pearl millet is to initiate an intensive search to identify sources of higher grain Fe and Zn content in this crop. This research reports on the extent of variability for Fe and Zn content in grains, the consistency of their expression across environments, and the relationship between Fe and Zn in a diverse range of materials, to assess the prospects of their genetic enhancement in cultivar development.