Precise transfers of genes for high grain iron and zinc from wheat-Aegilops substitution lines into wheat through pollen irradiation

Abstract

Nearly 2 billion people worldwide are suffering from iron (Fe) deficiency anemia and zinc (Zn) deficiency. The available elite bread wheat cultivars have inherently low grain micronutrient content. Biofortification for grain Fe and Zn content is one of the most feasible and cost-effective approach for combating widespread deficiency of the micronutrients. QTL controlling high grain Fe and Zn have been mapped on groups 2 and 7 chromosomes of Triticeae. The present study was initiated for precise transfers of genes for high grain Fe and Zn on group 2 and 7 chromosomes of wheat-Aegilops substitution lines to wheat cultivars using pollen radiation hybridization. The pollen radiation hybrids (PRH1) derived from 1.75 krad irradiated spikes showed the presence of univalents and multivalents in meiotic metaphase-I indicating the effectiveness of radiation dose. In the advanced generation PRH5, the plants selected with stable chromosome number and high grain Fe and Zn content were analyzed with wheat groups 2 and 7 chromosome specific intron targeted amplified polymorphism (ITAP) markers of the metal homeostasis genes to monitor the transfers of alien genes from the substituted Aegilops chromosomes. The group 2 chromosome derivatives showed the presence of NAS2, FRO2, VIT1, and ZIP2 Aegilops genes whereas the group 7 derivatives had YSL15, NAM, NRAMP5, IRO3, and IRT2 Aegilops genes. The pollen radiation hybrids of both the groups 2 and 7 chromosomes showed more than 30% increase in grain Fe and Zn content with improved yield than the elite wheat cultivar PBW343 LrP indicating small and compensating transfers of metal homeostasis genes of Aegilops into wheat.