Transferring iron genes to popular varieties : challenges and updates

Micronutrient deficiency popular termed as 'hidden hunger', includes Vitamin A, Zinc and Iron (Fe) deficiency. In the Philippines, Fe deficiency affects 39.4% of children under one year of age and 25.2% of nursing women. The level of iron in the rice grain is concentrated in the aleurone layer which is removed during milling therefore considerably reducing the grain-Fe concentration. HarvestPlus nutritionists recommend that 13 ppm Fe in polished rice grains is needed to supply approximately 30% estimated average daily requirement (EAR) for women and children. Biotechnological approaches were employed to introduce Fe-uptake genes into IR64 rice endosperm which resulted to 15 ppm Fe after milling. Introgression of the genes from two high-Fe events into six popular varieties (1-3 ppm of Fe) was conducted to test the trait stability of genes in different genetic backgrounds and to improve the iron content in these varieties. A marker-assisted backcross breeding approach was implemented under screenhouse conditions with full compliance to Philippine regulatory protocols. All progenies in every generation were selected using molecular markers to determine zygosity of the plants. Seven hundred F1 plants were produced, 500 of which were germinated for further backcrossing, agronomic selection at F2 and BC1F2 generation, and evaluation for iron content using an ionization technique called inductively coupled plasma mass spectrometry (ICP-MS). Progenies were found to have 12 ppm Fe. Results indicate a consistent pattern of inheritance of the trait until BC1F2 generation. Discarded seedlings and plant tissues produced after harvesting were disposed following Philippine biosafety regulations. Further backcrossing to produce BC5F5 generation will maximize recurrent parent background and phenotypic evaluation will be conducted in multi-location field trials. These trails will also provide yield and performance estimates under different environmental conditions and eventually satisfy all regulatory requirements, in preparation for the application for release.