Identification Of Maize Low Phytic Acid Inbred Lines And Primary Study Of Its Genetic Mechanism

From 65％to 80％of total P in mature seeds of the major grain crops is found in phyticacid. For basic cellular housekeeping functions, developing seeds need about 1 mg P pergram dry weight of tissue. During development nearly all additional P is synthesized intophytic acid (Ins P6). Since mature seed produced by grains and legumes contain from 3.0to 5.0 mg total P per gram, respectively, they therefore typically contain from 2.0 to 4.0 mgphytic acid P per gram. Applied interest in phytic acid primarily concerns its role as themajor form of P in seeds and its importance in human and animal nutrition. Developmentsin breeding "Low Phytate" crops and studies of the potential value of Low Phytate crops ashuman foods and animal feeds will resolve the bad affect of phytic acid. All lpa mutationsisolated to date result in reduced phytic acid accompanied by matching increases in seedinorganic P, resulting in the so-called "High Inorganic P" (HIP) seed phenotype, but havelittle impact on seed total P. Thus these Low Phytate crops have greatly increased"available P", at least when used in diets for non-ruminant animals such as poultry, swineand fish.In this study, the content of inorganic phosphorus of twenty maize inbred lines wereanalyzed, the inorganic phosphorus content of Qi319 is about 0.93μg/mg, which is higherthan control material (0.15μg/mg); further investigation indicated that the content of phyticacid in Qi319 grains is 1.31μg/mg, close to the maize lpa241/lpa241 mutant (1.20μg/mg)identified by Nielsen's lab in 2003, which is significantly lower than Lpa241/Lpa241wildtype and control maize inbred lines(＞2.8μg/mg). Genetic analysis indicated that thegene controlling low phytic acid of Qi319 is recessive and maybe allelic to lpa241/lpa241.In contrast with the low content of MIPS in lpa241/lpa241, the expression of MIPS inQi319 is increased significantly, suggested that both mutants were related to MIPS, buttheir mechanism is differ from each other. It is worthwhile to point out that the agronomicbehavior of reported lpa mutant is not satisfying for breeding applications, while Qi319 isa wildly used inbred line with several combinations in use. This discovery will broaden itsapplication and has provided a novel resource for lpa breeding program.