Impact of cross-breeding on the metabolites of the low phytic acid rice mutant Os-lpa-MH86-1.

Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate), the major storage form of phosphorus in cereals, is considered as an antinutrient in food and feed. During the past few years, various cereals have been subjected to mutation breeding for generating low phytic acid (lpa) crops. Recently, it was demonstrated that reduction of phytic acid in the rice mutant Os-lpa-MH86-1 obtained by gamma irradiation was due to a disruption of OsSULTR3;3, an orthologue of the sulfate transporter family group 3 genes. The application of a GC/MS-based metabolite profiling approach revealed that the reduction of phytic acid was accompanied by changes in concentrations of metabolites from different classes in the Os-lpa-MH86-1 mutant.Lpa mutant lines often exhibit lower grain yield and seed viability compared with their wild-type parents. To improve the agronomic performance of the Os-lpa-MH86-1 mutant, cross-breeding with a commercial cultivar was performed. The resulting progenies were genotyped using molecular markers to identify homozygous wildtype and lpa mutants from generations F4 to F7. The objectives of this study were: (i) to observe the consistent metabolic changes in Os-lpa-MH86-1 lpa mutants by following their composition over several independent field trials; (ii) to investigate the impact of cross-breeding on the phytic acid content and the metabolic phenotype of the homozygous lpa mutant; and (iii) to assess the stability of the mutation-specific metabolite signature in the lpa progenies over several generations. Statistical assessment of the data via multivariate and univariate approaches demonstrated that the lpa trait and the mutation-induced metabolite signature in the lpa progenies were comparable to the progenitor Os-lpa-MH86-1 mutant and consistently expressed over generations. These findings extend the basis for implementing mutation breeding in the generation of lpa rice cultivars.