Elemental composition of barley coleoptile papillae in relation to their ability to prevent penetration by Erysiphe graminis

Abstract

As part of an extended series of studies on the potential role of papillae in resisting fungal ingress, inorganic elements in microsurgically isolated normal papillae, induced by Erysiphe graminis in barley coleoptiles treated with Ca(NO 3 ) 2 , and oversize papillae, induced by the same fungus in coleoptiles treated with Ca(H 2 PO 4 ) 2 , were compared by X-ray microanalysis. The normal papillae, which have little or no effect on ingress of E. graminis , contained K and Ca as major components. By contrast, the oversize papillae, which can block ingress, contained copious amounts of P and Ca as major components. Cell wall pieces and cell fluids prepared from the above coleoptiles did not show prominent peaks of any elements in most cases. These results indicate that inorganic elements are deposited selectively into papillae and vary with the treatment of the host cells. Whether or not the exceptionally high levels of P and Ca in the oversize papillae are causally related to their ability to block fungal ingress is uncertain. However, the data suggest the possibility that the oversize papillae contain inhibitory levels of Ca(H 2 PO 4 ) 2 .