Clinton F. Hodges

Temperature and the Content of Specific Soluble Sugars of Poa pratensis Infected by Ustilago striiformis or Urocystis agropyri

The mean total soluble sugar content of sucrose, glucose, and fructose in Poa pratensis infected by Ustilago striiformis or by Urocystis agropyri was determined at 10, 20, and 30 C. Sugar content of healthy plants was greatest at 20 C, intermediate at 10 C, and lowest at 30 C Sucrose was most abundant at all temperatures Sucrose and glucose were most evenly distributed among leaves, crowns, roots, and rhizomes at 20 C The greater proportion of sucrose and glucose was in leaves at 10 and 30 C. Fructose was very low in healthy plants at 30 C. Plants infected by U. striiformis or by U agropyri showed a substantial decrease in mean total sugar content at all temperatures. The decrease in sugars induced by U. agropyri was greater than that caused by U. striiformis at 10 and 20 C Sucrose and glucose generally occurred in lesser quantities in the organs of plants infected with U. striiformis and U. agropyri than in healthy plants Crowns of U. agropyri-infected plants at 30 C contained more sucrose and glucose than their healthy controls. Fructose content of the organs of U. striiformis-infected plants was severely decreased at 10 and 20 C and was nondetectable at 30 C At 10 C, fructose was detected only in the leaves of U agropyri-infected plants The observations are discussed relative to survival of plants systemically infected by either pathogen under conditions of high temperature stress