Effect of sugar level on phleinase induction in stem base of orchardgrass after defoliation

Abstract

Yamamoto, S. and Mino, Y. 1987. Effect of sugar level on phleinase induction in stem base of orchardgrass after defoliation. The induction of phleinase (β‐D‐fructan fructohydrolase, EC 3.2.1.80) in stem base of orchardgrass ( Dactylis glomerata L. clone N‐377) after defoliation was studied in relation to the concomitant changes in sugar and protein levels. Phleinase activity in the stubble increased accompanied by a decrease in sucrose and glucose levels. This activity also increased under shading conditions without cutting. The induction of phleinase in excised stem base was suppressed by exogenously supplied glucose, fructose or sucrose. The suppression increased with increasing concentrations of glucose and it was not overcome by cyclic adenosine 3′,5′‐monophosphate. Protein level in the stem base decreased after defoliation and the decrease was reversed by exogenous glucose. Some hypotheses concerning the induction mechanism of phleinase are discussed.