Saturday, March 1, 2008

Chemotaxonomic significance of leaf wax n-alkanes in the Pinales (Coniferales)

BY : M. MAFFEI, S. BADINO and S. BOSSI


The chemotaxonomic significance of leaf wax n-alkanes was studied in 112 species and cultivars belonging to the Pinaceae, Cupressaceae, Podocarpaceae, Araucariaceae, Cephalotaxaceae, Sciadopityaceae and Taxaceae (Pinales). In general, n-alkanes ranged from 18 to 34 carbon numbers. In the Pinales, C31 was the most abundant n-alkane (20.17%±1.68), followed by C27 (2.84%±0.41), C29 (2.59%±0.49) and C25 (2.41%±0.22). In the Araucariaceae, n-alkane composition was characterized by low relative percentages of C31 (5.23%±1.58), whereas the Cephalotaxaceae were characterized by high percentages of C29 (31.95%±2.05) and C27 (28.00%±1.00). The Cupressaceae had a mean composition of n-alkanes characterized by moderate percentages of C31 (18.31%±2.32) and C33 (5.36%±1.07), whereas in the Pinaceae, C31 was the main n-alkane (25.40%±2.56). The Podocarpaceae were characterized by moderate percentages of C29 (12.69%±9.16), C31 (10.77%±2.70), C27 (7.37%±5.83) and C33 (6.59%± 5.71), whereas the Taxaceae had high percentages of C31 (34.94%±7.85). Sciadopitys verticillata showed low percentages of all n-alkanes. Discriminant Analysis (DA) of the Araucariaceae, Cupressaceae and Pinaceae showed a good discrimination among subfamilies. Cluster Analysis (CA) and Principal Component Analysis (PCA) performed on species of the Pinales, showed a good separation among the families. The direct comparison of the present data with those obtained on species belonging to eleven angiosperm families provided further evidence of the chemotaxonomic significance of leaf wax n-alkanes.

From Journal of Biological Research

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