Molecular Genetics and Genomics

, Volume 286, Issue 2, pp 119–133

Identification of genes necessary for wild-type levels of seed phytic acid in Arabidopsis thaliana using a reverse genetics approach

Original Paper

DOI: 10.1007/s00438-011-0631-2

Cite this article as:
Kim, S. & Tai, T.H. Mol Genet Genomics (2011) 286: 119. doi:10.1007/s00438-011-0631-2

Abstract

The majority of phosphorus (P) in seeds is found in phytic acid (InsP6) which accumulates as the mixed salt phytate. InsP6 is generally considered to be an anti-nutrient and the development of low phytic acid (lpa) seed crops is of significant interest. We have employed a reverse genetics approach to examine the impact of disrupting genes involved in inositol phosphate metabolism on Arabidopsis seed InsP6 levels. Our analysis revealed that knockout mutations in three genes (AtITPK1, AtITPK4, and AtMIK/At5g58730) reduced seed InsP6 in addition to knockouts of four previously reported genes (AtIPK1, AtIPK2β, AtMRP5, and At5g60760). Seeds of these lpa mutants also exhibited reduced germination under various stress conditions. The greatest reduction in InsP6 (>70%) was observed in atmrp5 seeds which were also among the least sensitive to the stresses examined. Expression analysis of the lpa genes revealed three distinct patterns in developing siliques consistent with their presumed roles. Disruption of each lpa gene resulted in changes in the expression in some of the other lpa genes indicating that transcription of lpa genes is modulated by other constituents of InsP6 metabolism. While all the lpa genes represent possible targets for genetic engineering of low phytate seed crops, mutations in AtMRP5,AtMIK, and At5g60760 may be most successful for conventional approaches such as mutation breeding.

Keywords

Phytic acidArabidopsisInositol phosphate metabolismKinasesReverse genetics

Abbreviations

BLASTp

Basic local alignment search tool protein–protein

DAF

Days after fertilization

GADPH

Glyceraldehyde 3-phosphate dehydrogenase

HPIC

High-performance ion chromatography

Ins

Inositol

InsP

Inositol (poly)phosphate

PtdIns

Phosphatidylinositol(s)

lpa

Low phytic acid

P

Phosphorus

Pi

Inorganic phosphate

RT-PCR

Reverse transcription-polymerase chain reaction

SAIL

Syngenta Arabidopsis insertion lines

SALK

Salk Institute

T-DNA

Transfer DNA

Supplementary material

438_2011_631_MOESM1_ESM.pdf (191 kb)
Supplementary material 1 (PDF 190 kb)

Copyright information

© Springer-Verlag (outside the USA) 2011

Authors and Affiliations

  1. 1.Crops Pathology and Genetics Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Department of Plant Sciences – MS 1University of CaliforniaDavisUSA