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Fatty acid composition of chlorenchyma membrane fractions from three desert succulents grown at moderate and high temperatures

1985; Elsevier BV; Volume: 820; Issue: 1 Linguagem: Inglês

10.1016/0005-2736(85)90220-2

1879-2642

S. Chuan Kee, Park S. Nobel,

Photosynthetic Processes and Mechanisms

To help understand the tolerances of desert succulents to extremely high temperatures (above 60°C), the effect of growth temperature on fatty acid composition of various membrane fractions from three species was investigated. When maintained at day/night air temperatures of 30°C/20°C, their chlorenchyma fatty acid compositions were similar to one another and to those of mesophytic leaves, except that desert succulents had appreciably less linolenic acid (18:3) and more oleic acid (18:1) and hence greater fatty acid saturation. The differences were observed in the chloroplast, mitochondrial and microsomal fractions and were more apparent in the nonpolar lipids than the total lipids. For all membrane fractions of Ferocactus acanthodes, a shift to 50°C/40°C resulted in a decrease in 18:3 and an increase in 18:1 and hence an increase in fatty acid saturation level. For Agave deserti and Carnegiea gigantea, however, increasing the day/night air temperatures did not result in increased fatty acid saturation, although their high-temperature tolerances increase about as much as that of F. acanthodes as the air temperature is increased. Thus, acquisition of high-temperature tolerance need not be accompanied by marked changes in fatty acid saturation or composition.