The Influence of Phosphate Uptake on Cation Uptake in Fusarium oxysporum f. sp. vasinfectum

Abstract

Abstract Fusarium oxysporum grown in a low phosphate medium was found to take up several times as much K from KH2PO4 as from KCI solutions. Large amounts of phosphate also were taken up from KH2PO4. Similar large uptakes of Na and phosphate took place from solutions of NaH2PO4. Substantial quanties of phosphate were taken up from solutions of Ca(H2PO4)2 in the absence of any appreciable Ca uptake. When the fungus was grown in a medium containing high phosphate, little or no uptake of phosphate from KH2PO4 solutions occured and the K Uptake was at the same level as from KCI solutions. During large phosphate uptake sizable reductions in the organic acid content of the fungal cells were observed. Much, but not all, of the data could be explained on the basis of maintenance of charge balance within the cells. – The respiratory rate of fungus, grown in a low P medium, was markedly increased in KH2PO4 solution. Fungus, grown in a medium with high phosphate, had a higher respiratory rate which showed only a slight response to KH2PO4 solution. Fungus, grown in a medium with high phosphate, had a higher respiratory rate which showed only a slight response to KH2PO4.