Fatty Acids and Circadian Rhythms in Phaseolus coccineus

Abstract

Five major fatty acids, palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2) and linolenic (18:3), were identified in polar lipid extracts from pulvini of Samanea saman and P. coccineus [cv. Scarlett Runner]. In P. coccineus their distribution varied quantitatively in the laminar pulvinus, petiolar pulvinus, petiole, stem, leaf and root. Short pulses of red light did not greatly affect the relative quantities of fatty acids in dark grown P. coccineus, but a 30 min exposure of red light generally increased the degree of unsaturation by increasing linolenic acid and decreasing linoleic and palmitic acids. P. coccineus seeds were exposed to several substituted pyridazinones and cerulenin and dimethylethanolamine. The pyridazinones San 6706 [4-chloro-5-(dimethylamino)-2-(.alpha.,.alpha.,.alpha.-trifluoro-m-tolyl)-3(2H)pyridazinone] and norflurazon altered fatty acid composition but also altered morphology and inhibited chlorophyll synthesis. Exposure to 10.degree. C for 72 h caused a small but significant increase in the degree of unsaturation of P. coccineus fatty acids but results were equivocal with S. saman.