Premium
Response of Digitaria decumbens Leaf Carbohydrate Levels and Glucan Degrading Enzymes to Chilling Night Temperature
Author(s) -
Shatters Robert G.,
West S. H.
Publication year - 1995
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1995.0011183x003500020039x
Subject(s) - biology , digitaria , starch , sucrose phosphate synthase , carbohydrate , sucrose , horticulture , carbohydrate metabolism , botany , amylase , phaseolus , zoology , sucrose synthase , invertase , enzyme , food science , biochemistry
Experiments were performed to analyze how chilling temperatures present during the night period affect leaf carbohydrate metabolism in pangolagrass ( Digitaria decumbens Stent.), a warm‐season forage grass. Plants were exposed to three consecutive 14‐h night periods of either 25 or 10°C. Control plants (25°C nights) displayed an average 75% decline in leaf glucose levels during the night. This decline was more than 50% smaller in chilled plants (10°C nights) during all three nights. In control plants, leaf sucrose levels declined 78% during the night period. In chilled plants, this decline was inhibited to less than 2% of the available sucrose during the first night, and 47 and 44%, respectively, during two subsequent chilling nights. Greater than 90% of leaf starch was mobilized in control plants during the night, whereas 52, 46, and 16% of leaf starch was mobilized during three consecutive chilling nights, respectively. Chilling did not cause observable alterations in the ex planta activity of specific amylase enzymes; however, two diurnally regulated extrachloroplastic amylolytic enzymes were identified. Total leaf α‐1,4‐glucan phosphorylase (GP) activity was diurnally regulated with highest activity at the end of the night period, and activity increased in chilled plants after two consecutive chilling nights. Therefore, during three consecutive chilling nights the diurnal fluctuations in neither leaf carbohydrate levels nor GP activity remained constant. This dynamic response indicates that previous chilling night exposure influenced subsequent night‐period carbohydrate metabolism despite each night period being separated with a warm (25–33°C) 10‐h d period.