Development, characterization, and gene mapping of low phytate mutations in rice

Phytic acid (PA, myo-inositol 1,2,3,4,5,6-hexakisphosphate) is the primary storage form of phosphorus (P) in cereal seeds - accounting for about 65-85% of the total P. It is widely regarded as the major anti-nutrient component in cereal and legume grains including rice. By using gamma irradiation, we developed a dozen low phytic acid (LPA) mutant lines in the past 5 years. The LPA traits of those mutant lines were controlled by at least four non-allelic genes; we have mapped four genes to different positions in chromosome 2, 3 and 4, and three genes were identified to be responsible for three non-allelic mutations. Field agronomic trials showed that LPA mutations could affect, mostly at significant levels, the grain weight and yield, seed viability and storability. However, the inferior performance of the LPA lines could be improved through cross breeding and targeted selection. (author)