Low-oxalate spinach mutant induced by chemical mutagenesis

Abstract

Spinach (Spinacia oleracea L.) accumulates large amounts of oxalate, which reacts with calcium, inhibiting its absorption and forming urinary stones in humans. In this study, low-oxalate spinach mutant was induced through chemical mutation. Seeds of the gynomonoecious line of 'Shin-Nippon' were treated with 50 mM ethyl methane sulphonate (EMS) for 6 h. Self-fertilized M2 seeds were harvested from Mj plants individually. Total oxalate (water soluble and insoluble) concentrations of M2 plants were measured, and four low-oxalate plants were selected. Self-fertilized M3 seeds were harvested from these M2 plants individually. In the progenies of three M2 plants, oxalate concentration ranged from 9 to 19 mg-g'FW; there were no low-oxalate plants; however, in the progeny of one M2 plant, five of eight plants had low oxalate; their concentration were lower than 2 mg-g'FW. Self-fertilized M4 seeds were harvested from low-oxalate M3 plants individually. The progenies of low-oxalate M3 plants, named low-oxalate lines, were grown and compared with the original 'Shin-Nippon' and gynomonoecius line (wild types). Leaves of low-oxalate lines were slightly smaller and thinner than wild types, whereas the leaf number and color were similar. Oxalate concentrations of leaves in low-oxalate lines strongly decreased; one third to one sixth of those in wild types. Nitrate concentrations did not decrease in low-oxalate lines.