TITLE	Effects of three allelopathic phenolics on chlorophyll accumulation of rice (Oryza sativa) seedlings: I. Inhibition of supply-orientation
AUTHOR	Chi-Ming Yang Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 11529, Republic of China Chyoung-Ni Lee Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 11529, Republic of China Chang-Hung Chou* Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 11529, Republic of China
FULL TEXT	[in HTML format] [in PDF format]
ABSTRACT	The effects of three allelopathic chemicals, o-hydroxyphenyl acetic, ferulic, and p-coumaric acids, on the chlorophyll (Chl) supply-orientation in the rice leaf (Oryza sativa cul. TN67) were investigated. Two-week-old etiolated seedlings of rice were cultured in growth chamber in one-tenth Kimura's culture solution, with or without 25, 50 or 100 ppm of the phenolic compounds. The photoperiod, light intensity, and relative humidity were 12 h, 300 µmol/m2s, and 70%, respectively. Leaves were harvested at 1, 3, 6, 12, 24 and 48 h after treatment with phenolics. The concentrations of Chl and its three biosynthetic porphyrin precursors__i.e. protoporphyrin IX (Proto), Mg-protoporphyrin IX (Mg-Proto), and protochlorophyllide (Pchlide)__were determined, and the mole percent of total porphyrins was calculated. Accumulation of Chl and porphyrin contents were more inhibited as the phenolic concentrations increased. While the mole percent of Mg-Proto affected by the three allelochemical phenolics exhibited the same pattern, those of Proto and Pchlide showed quite different patterns of change in concentration. The data strongly suggest that Mg-chelatase may be the major target of the three phenolics. The order of inhibition strength is ferulic acid>p-coumaric acid>o-hydroxyphenyl acetic acid. It is concluded that the supply-orientation of Chl is significantly inhibited by the exogenous phenolics, causing the shortage of Chl.
KEYWORD	Allelopathic phenolic; Chlorophyll; Ferulic acid; o-hydroxyphenyl acetic acid; Oryza sativa; p-coumaric acid porphyrin; Supply-orientation;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 43 Number 4 October 2002, page 299-304, 6 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China