Effect of several germination conditions on total P, phytate P, phytase, acid phosphatase activities and inositol phosphate esters in spring and winter wheat

Abstract

Changes in the wheat phosphatases (phytase-Phy and acid phosphatase-AcPh) and the degradation of their substrates (inositol phosphates esters) during seed germination have been examined in two studies. Germinated grains with high phytate degrading enzymes are of potential interest in the improvement of phosphorus availability in monogastric animals. In the first study, the seeds were soaked for 1 and 14 h and germinated for 3 and 5 days with and without the addition of gibberellic acid (GA3). In the second study, the seeds were soaked for 1 h and germinated for 1, 3 and 5 days with GA3. Phytase (up to 1800 and 1573 U/kg) and acid phosphatase (up to 13 115 and 10 154 U/g) activities and IP₆ (6·96 and 7·67 mg/g), IP₅ (0·40 and 0·60 mg/g) and IP₄ (0·04 and 0·04 mg/g) were detected in ungerminated spring and winter wheat, respectively. The germination process caused a significant increase of Phy and AcPh activities in spring (up to 275 and 235%) and winter wheat (up to 250 and 329%) and a reduction in the phytate phosphorus content (up to 35 and 64%, respectively). Phytate phosphorus content was affected in both spring and winter wheat by the soaking time. Finally, during the course of germination, IP₆ and IP₅ were more rapidly degraded in winter wheat (62 and 62%) than in spring wheat (32 and 29%), and IP₄ was only a short-living intermediate, which was increased during hydrolysis and degraded to IP₃. In conclusion, the germination process caused a significant increase of Phy and AcPh in spring and winter wheat, which was accompanied with a significant reduction of phytate phosphorus content and an increase in the content of lower inositol phosphates.