title: Herbicidal effects of harmaline from Peganum harmala on photosynthesis of Chlorella pyrenoidosa: probed by chlorophyll fluorescence and thermoluminescence.
abstract: The herbicidal effects of harmaline extracted from Peganum harmala seed on cell growth and photosynthesis of green algae Chlorella pyrenoidosa were investigated using chlorophyll a fluorescence and thermoluminescence techniques. Exposure to harmaline inhibited cell growth, pigments contents and oxygen evolution of C. pyrenoidosa. Oxygen evolution was more sensitive to harmaline toxicity than cell growth or the whole photosystem II (PSII) activity, maybe it was the first target site of harmaline. The JIP-test parameters showed that harmaline inhibited the donor side of PSII. Harmaline decreased photochemical efficiency and electron transport flow of PSII but increased the energy dissipation. The charge recombination was also affected by harmaline. Amplitude of the fast phase decreased and the slow phase increased at the highest level of harmaline. Electron transfer from QA(-) to QB was inhibited and backward electron transport flow from QA(-) to oxygen evolution complex was enhanced at 10 μg mL(-1) harmaline. Exposure to 10 μg mL(-1) harmaline caused appearance of C band in thermoluminescence. Exposure to 5 μg mL(-1) harmaline inhibited the formation of proton gradient. The highest concentration of harmaline treatment inhibited S3QB(-) charge recombination but promoted formation of QA(-)YD(+) charge pairs. P. harmala harmaline may be a promising herbicide because of its inhibition of cell growth, pigments synthesis, oxygen evolution and PSII activities.
authors.affiliation: Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; College of Tourism and Geography, Yunnan Normal University, Kunming 650500, China.
authors.forename: Chunnuan
authors.initials: C
authors.lastname: Deng
authors.affiliation: Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Shao
authors.affiliation: Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China. Electronic address: xiangliangpan@163.com.
authors.forename: Xiangliang
authors.initials: X
authors.lastname: Pan
authors.affiliation: Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shuzhi
authors.initials: S
authors.lastname: Wang
authors.affiliation: Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
authors.forename: Daoyong
authors.initials: D
authors.lastname: Zhang
mesh_terms: D002708:Chlorella / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism*; D000077194:Chlorophyll A; D004579:Electron Transport / Q000187:drug effects; D005453:Fluorescence; D006246:Harmaline / Q000302:isolation & purification / Q000494:pharmacology*; D006540:Herbicides / Q000302:isolation & purification / Q000494:pharmacology*; D008163:Luminescent Measurements; D032443:Peganum / Q000737:chemistry*; D010788:Photosynthesis / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*
chemical_list: D006540:Herbicides; D010936:Plant Extracts; D002734:Chlorophyll; D006246:Harmaline; D000077194:Chlorophyll A
keywords: Charge recombination; Photosystem II; Phytotoxin; Proton gradient; Q(A)(−) reoxidation; Thermoluminescence