Identification of a Phytase Gene in Barley (Hordeum vulgare L.)

Fei Dai,Long Qiu,Dezhi Wu,Meixue Zhou,Lingzhen Ye,Guoping Zhang

doi:10.1371/journal.pone.0018829

Abstract

BackgroundEndogenous phytase plays a crucial role in phytate degradation and is thus closely related to nutrient efficiency in barley products. The understanding of genetic information of phytase in barley can provide a useful tool for breeding new barley varieties with high phytase activity.Methodology/Principal FindingsQuantitative trait loci (QTL) analysis for phytase activity was conducted using a doubled haploid population. Phytase protein was purified and identified by the LC-ESI MS/MS Shotgun method. Purple acid phosphatase (PAP) gene was sequenced and the position was compared with the QTL controlling phytase activity. A major QTL for phytase activity was mapped to chromosome 5 H in barley. The gene controlling phytase activity in the region was named as mqPhy. The gene HvPAP a was mapped to the same position as mqPhy, supporting the colinearity between HvPAP a and mqPhy.Conclusions/SignificanceIt is the first report on QTLs for phytase activity and the results showed that HvPAP a, which shares a same position with the QTL, is a major phytase gene in barley grains.

Highlights

Phytic acid, myo-inositol 1, 2, 3, 4, 5, 6-hexakisphosphate (InsP6), is a principle storage form of phosphorus (P) and inositol in cereal grains, and it is an effective polyanionic chelating agent [1]
Conclusions/Significance: It is the first report on Quantitative trait loci (QTL) for phytase activity and the results showed that HvPAP a, which shares a same position with the QTL, is a major phytase gene in barley grains
This study aimed at identifying QTLs controlling phytase activity using a doubled haploid population; purifying and characterizing phytase proteins; and clarifying the relationship between the gene in the QTL region and different isoforms of purple acid phosphatase (PAP) gene

Summary

Introduction

Myo-inositol 1, 2, 3, 4, 5, 6-hexakisphosphate (InsP6), is a principle storage form of phosphorus (P) and inositol in cereal grains, and it is an effective polyanionic chelating agent [1]. Phytate deposition plays an important role in storage and homeostasis of both P and some other mineral nutrients during grain development and maturation [2]. Reduction of phytate levels or increase in phytase activity in plant seeds is an alternative strategy for improving nutrient efficiency in animal production [5]. Phytate was degraded during food processing by enhancing natural phytase activity or by phytase pretreatment of legume and cereal grains [7]. The enhancement of endogenous phytase activity of cereal grains could improve the bioavailability of mineral nutrients in cereals [8,9,10]. Endogenous phytase plays a crucial role in phytate degradation and is closely related to nutrient efficiency in barley products. The understanding of genetic information of phytase in barley can provide a useful tool for breeding new barley varieties with high phytase activity

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