Comparison of acid phosphatases in two genotypes of white clover with different responses to applied phosphate

Two white clover (Trifolium repens L.) genotypes, identified by their diffe ring ability to increase in biomass in response to added phosphorus (P) (hi gh P responder, low P responder) were subjected to P deprivation and examin ed for differences in root growth, root surface acid phosphatase activity, and soluble and ionically-bound root cell wall isoform profile. As leaf P l evels declined, the high P responder showed a greater increase in biomass a llocated to the roots, and highest root surface acid phosphatase activity. However, these differences were not statistically significant. The onset of P deprivation enhanced the intensity of several acid phosphatase isoforms in the P deprived root extracts from both genotypes. After 11 days, one bas ic isoform (resolved at pH 4.5) was enhanced in the cell wall extract, an e nhancement that was also observed after 26 days. However, for the soluble i soforms, a temporal separation of response was observed in both genotypes. After 11 days, there was no discernable enhancement of the major staining b asic isoform or in the major staining acidic isoform (resolved at pH 8.8) i n extracts from P-deprived roots. After 26 days, these isoforms were enhanc ed in extracts from P-derived root tissues. Further, a second acidic isofor m could now be discerned as a major staining enzyme in P-derived root extra cts from both genotypes.