Humic substances affect the activity of chlorophyllase.
Three humic substances--humic acid, fulvic acid, and humin--were isolated from soils located in the northern and southern forests of the Yuanyang Lake Nature Preserve in northern Taiwan's Ilan County. Aqueous extracts of fresh wet soil and of three humic substances, at concentrations of 0.125, 0.25, and 0.5 mg/ml, were investigated for their effects on the activities of chlorophyllase a and b. Aqueous extracts of forest soils at the northern and southern bank, dominated by the pure vegetation of Formosan False cypress (Chamcaecyparis formosensis Matsum), stimulate both chlorophyllase a and b activities, while those of the southern bank, dominated by a Taiwanese Miscanthus (Miscanthus transmorrisonensis Hayata), inhibits such activities. All three humic substances, despite their soil sources, stimulate the activities of both chlorophyllase a and b. Fulvic acid stimulates more chlorophyllase a activity than either humic acid or humin. Humic acid stimulates more activity of chlorophyllase b than either fulvic acid or humin. Humin exhibited the least effect on chlorophyllase a and b. It is suggested that humic substances in the soil may accelerate the chlorophyll degradation of litter in the ecosystem and that chlorophyllase a and b may be different enzymes.
Yang
Chi-Ming
CM
Institute of Botany and Research Center for Biodiversity, Academia Sinica, Nankang, Taipei, Taiwan 115, Republic of China. cmyang@gate.sinica.edu.tw
Wang
Ming-Chao
MC
Lu
Yi-Feng
YF
Chang
Ing-Feng
IF
Chou
Chang-Hung
CH
D001578:Benzopyrans / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002265:Carboxylic Ester Hydrolases / Q000187:drug effects / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D017753:Ecosystem; D006812:Humic Substances / Q000032:analysis / Q000633:toxicity*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis; D013624:Taiwan; D014873:Water Pollutants / Q000032:analysis / Q000633:toxicity*
D001578:Benzopyrans; D006812:Humic Substances; D012989:Soil Pollutants; D014873:Water Pollutants; D002734:Chlorophyll; D002265:Carboxylic Ester Hydrolases; C019875:chlorophyllase; C005023:fulvic acid