Germplasm evaluation and identification of donors for Biofortification: A set of 250 germplasm lines including varieties and land races collected from different parts of the country and maintained at Rice Genetics, IARI were phenotyped for their grain Fe and Zn concentration through XRF and protein concentration through Kjeldhal method. Fe and Zn concentrations ranged from 6.5 – 23.1 ppm and 13 – 50.2 ppm respectively in brown rice. Polishing the same genotypes significantly reduced the Fe and Zn concentration and they were in the range of 0.7 – 12.3 ppm and 8.2 – 44.9 ppm, respectively. The crude protein content of the varieties as estimated using Kjeldhal method was in the range of 3.4 – 10.89 %. The genotypes with high concentration of Fe, Zn and protein were used as donors for Biofortification.
Identification of low phytate N22 mutants: A set of EMS induced mutants in the genetic background of an upland variety N22, available with the center were screened for the low phytic acid (lpa) trait. These mutants have been identified through the use of a high inorganic phosphate (HIP) colorimetric assay which is based on the inverse relationship of inorganic phosphate and phytic acid content (Raboy et al., 2000).
Association mapping for grain Fe, Zn and Protein: A set of 192 rice germplasm accessions representing variability for Fe and Zn content in brown rice and polished rice were genotyped with 50K SNP markers for genome wide association study (GWAS). GWAS resulted in the identification of a total of 39 SNP markers with 15 SNPs associated with Fe in brown rice, 13 with Fe in polished rice, 7 with Zn in brown rice and 4 with Zn in polished rice. These markers explained 9 to 43% of the phenotypic variance across the traits suggesting the significance of these genomic regions in the development of biofortified rice varieties through molecular breeding.
Development of mapping populations for mapping grain nutrient traits: F2:3 populations of the crosses GP451 X GP748, GP926 X GP397, GP493 X GP418 segregating for Fe, Zn and protein content developed.
Survey of molecular polymorphism between the parents: A total of 652 SSR markers were screened between the parents of the crosses GP451/GP748, GP926/GP397 and GP493/GP418 segregating for grain Fe, Zn and protein. The number of polymorphic markers ranged from 110 to 135 and the percentage polymorphism ranged from 17 to 20.
Validation of reported QTL linked markers: A total of 35 QTL linked markers published in different studies were assayed for the polymorphism between the high and low parents for the three nutritional traits and identified eight markers viz. RM234, RM3331, RM7, RM517, RM501, RM7102, RM106 and RM 421 to be polymorphic between high and low parents for grain Zn content in polished rice while two markers RM7 and RM501 were polymorphic between the parents for grain Fe content in polished rice.
Markers Assisted Backcross Breeding for introgression of Iron and Zinc QTLs in the background of export quality basmati variety Pusa Basmati 1121: Foreground selection was done in BC1F1 generation derived from cross (PB1121/GP451//PB1121*1) and (PB1121/GP926//PB1121*1) by using 5 QTL linked markers for Fe and six QTL linked markers for Zn and plants positive for all the tested QTL linked markers were backcrossed with recurrent Parent PB1121 for generation of BC2F1 seeds.
