Variations of the composition of the leaf cuticular wax among Chinese populations of Plantago major.

Abstract

Plantago major L. grows in a very wide range of regions in China and exhibits great variations among populations. The analysis of the cuticular-wax composition provides a potential approach to classify populations of P. major confronting different environmental conditions. Twelve populations of P. major and five populations of P. depressa Willd., distributed over regions with average annual temperatures ranging from -2.0 to 18.4°, were sampled, the variation of the composition of their cuticular waxes was analyzed, and their values of average chain length (ACL) and carbon preference index (CPI) were calculated. Great intra- and interspecies variations were observed for the total wax contents. The average annual temperature of the habitats was significantly correlated with the relative contents of the dominant n-alkanes with an odd number of C-atoms, but not with the wax contents. With an increasing average annual temperature, the relative contents of n-alkanes C29 and C31 decreased, whereas those of C33 and C35 as well as the values of ACLtotal and ACL27-33 increased. Cluster analysis based on the pattern of the n-alkane distribution allowed to clearly separate the populations of P. major according to the average annual temperature of their habitats, but not to separate the populations of the two species. Hence, the pattern of the n-alkane distribution might be a good taxonomic marker for P. major at the intraspecies level, but not at the interspecies level. Nevertheless, a small difference between the populations of the two species was observed concerning the values of ACLtotal and CPItotal , implying the potential use of these indices for the classification of the populations of the two species at the interspecies level.