Submitted to: Journal of Heredity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/29/2014
Publication Date: 7/30/2014
Citation: Raboy, V., Cichy, K.A., Peterson, K., Reichman, S., Sompong, U., Srinives, P., Saneoka, H. 2014. Barley (Hordeum vulgare L.) low phytic acid 1-1: an endosperm-specific filial determinant of seed total phosphorus. Journal of Heredity. 105:656-665. Interpretive Summary: Enhancing the management of the phosphate use in agricultural production, both in animal feeds and in crop production, is an objective of growing importance throughout the United States and across the world. High levels of phosphate in animal waste can contribute to water pollution. Phosphate fertilizer is key to high crop yields but sources of readily available rock phosphate used for fertilizer production are diminishing. Breeding crops that efficiently use soil phosphate, and that when used in feeds provide nutritionally available forms of phosphate to livestock, remain important research objectives, but the role of seed phosphate has been overlooked. However, crop seed phosphate represents an important opportunity for engineering enhanced phosphate utilization in crop production. This research reports the first gene, barley low phytic acid 1, shown to be important to the uptake and distribution of phosphate in seeds. This new genetic information provides a novel approach to engineering crops the more efficiently use phosphate
Technical Abstract: In cultivated cereal and legume seed crops, inositol hexaphosphate (Ins P6 or “phytic acid”) typically accounts for 75% (±10%) of seed total phosphorus (P). Genetic blocks in seed Ins P6 accumulation in some cases can also alter the distribution or total amount of seed P. In non-mutant barley (Hordeum vulgare L.) caryopses, ~80% of Ins P6 and total P accumulate in the aleurone layer, the outer layer of the endosperm, with the remainder in the germ. In seed homozygous for barley low phytic acid 1-1 (Hvlpa1-1), both endosperm Ins P6 and total P are reduced, by ~45% and ~25%, respectively. Germs however are wild-type for both Ins P6 and total P. This translates into a net reduction in whole seed total P of ~15%. Nutrient culture and genetic studies demonstrate that the reduction in endosperm total P is not due to a reduction in the uptake of P into the maternal plant (source P), or to any maternal effect. Genetic tests indicate that sibling seed in the same head of barley that differ in their Hvlpa1-1 genotype (heterozygous versus homozygous recessive) differ in their total P (normal versus reduced, respectively). Therefore the Hvlpa1-1 genotype of the filial seed conditions the seed total P reduction. Thus Hvlpa1 functions as a seed-specific or filial determinant of cereal endosperm total P.