Ij. Tetlow et Jf. Farrar, APOPLASTIC SUGAR CONCENTRATION AND PH IN BARLEY LEAVES INFECTED WITH BROWN RUST, Journal of Experimental Botany, 44(262), 1993, pp. 929-936
Soluble sugars were extracted by low speed centrifugation from the apo
plast of leaves of barley (Hordeum distichum L.) infiltrated with wate
r. Infection of the leaf with the brown rust fungus (Puccinia hordeii)
resulted in a reduction in the concentration of sucrose, glucose and
fructose in the apoplast. Sugars were present in an apoplastic space o
ccupying 12 and 17 cm3 M-2 of leaf area in healthy and infected tissue
, respectively. Uptake of hexoses by intercellular hyphae is suggested
as a cause of this reduction. The pH of apoplastic sap extracted from
rust-infected leaves was increased to pH 7.3 from pH 6.6 in controls.
The effect of a reduced apoplastic sugar pool and increased pH on exp
ort from infected leaves is discussed.