Chemotaxonomic significance of leaf wax n-alkanes in the Pinales (Coniferales) |
M. MAFFEI, S. BADINO and S. BOSSI |
Abstract
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.
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