low phytic acid1-1 does not affect sugar metabolism in sugary1 kernels

Sweet corn (Zen mays L.) kernel sucrose concentration is determined by gene tic and physiological factors that affect carbohydrate metabolism during ke rnel development. Phosphorus homeostasis via phytic acid metabolism may pla y a role in carbohydrate metabolism Isolines and isohybrids that were homoz ygous sugary1 and either homozygous for the wild-type Low phytic acid 1 (LP a1) allele, or the recessive lpa1-1 allele, R ere produced. As originally o bserved in starchy genetic backgrounds, seed phytic acid was greatly reduce d and inorganic P greatly increased, both during development and at maturit y, in su1:lpa1-1 as compared with su1:Lpa1 grain. This perturbation in kern el P metabolism had little discernable effect on kernel sugar and water-ins oluble starch concentrations during development and at maturity. However ma ture kernel phytoglycogen (soluble starch) concentration was 43% greater in lpa1-1/su1 grain as compared with Lpa1/su1 grain. These results support th e conclusion that normal seed phytic acid metabolism plays a relatively min er role in P homeostasis during development. No preference difference betwe en these two su1 types was detected by a trained taste panel. This supports the possibility that the "low phytic acid" trait, of possible value in imp roving the nutritional quality of staple foods, can be introduced into food corns without having a large affect on their acceptability.