Micronutrient productivity: a comprehensive parameter for biofortification in rice (Oryza sativa L.) grain

BACKGROUND Enhancing the micronutrient content of staple crops such as rice will improve human nutrition and address the problem of hidden hunger globally. Rice grains consumed after polishing lack adequate amounts of micronutrients. The present study aims to reveal the effects of polishing on micronutrient content and to identify superior genotype(s) to improve yield and micronutrient content after polishing. RESULTS AM65 exhibited the highest zinc content, and AM180 had the highest iron content, even after polishing. There was little or no difference between the genotypes for zinc content in bran, indicating a possible threshold for micronutrient accumulation in the aleurone layer. A comprehensive selection criterion called ‘micronutrient productivity’ was used to select for both yield and micronutrient parameters. AM65 and ARB6 showed high zinc and iron productivity indices. OsZIP4b and OsZIP6c markers showed an association with iron content on an agarose gel. Sequencing of markers revealed that OsYSL15 and OsZIP6c were associated with grain zinc content and OsZIP3b, OsMTP1a, and OsYSL4b with grain iron content. These markers can be used for selecting superior accessions. CONCLUSION AM65 was loaded with micronutrients and manifested a positive correlation with the grain yield, and it is undoubtedly ‘super elite’. Bran does not drain the grain but rather acts as gateway for micronutrient transportation to the endosperm. Micronutrient productivity is a comprehensive parameter for the biofortification of grain. © 2018 Society of Chemical Industry