Terpenes as Useful Markers in Differentiation of Natural Populations of Relict Pines Pinus heldreichii, P. nigra, and P. peuce

Abstract

Comparative analysis of terpene diversity and differentiation of relict pines Pinus heldreichii, P. nigra, and P. peuce from the central Balkans was performed at the population level. Multivariate statistical analyses showed that the composition of needle terpenes reflects clear divergence among the pine species from different subgenera: P. peuce (subgenus Strobus) vs. P. nigra and P. heldreichii (subgenus Pinus). In addition, despite the described morphological similarities and the fact that P. nigra and P. heldreichii may spontaneously hybridize, our results indicated differentiation of their populations naturally growing in the same area. In accordance with recently proposed concept of 'flavonic evolution' in the genus Pinus, we assumed that the terpene profile of soft pine P. peuce, defined by high amounts of six monoterpenes, is more basal than those of hard pines P. nigra and P. heldreichii, which were characterized by high content levels of mainly sesquiterpenes. In order to establish precise positions of P. heldreichii, P. nigra and P. peuce within the taxonomic and phylogenetic tree, as well as develop suitable conservation strategies and future breeding efforts, it is necessary to perform additional morphological, biochemical, and genetic studies.

Chemotaxonomic Considerations of the n‐Alkane Composition in Pinus heldreichii, P. nigra, and P. peuce

“…In this analysis 50 – 100% of individuals were classified correctly. These results are in agreement with PCA ( Figure ), but quite opposite of those based on terpene analysis of the same species, where through DA analysis P. nigra populations were grouped together with those of P. heldreichii , while P. peuce populations were separated.…”

“…There was no separation between populations of P. heldreichii and P. peuce on the plain of axis 2 (22.3%), although those of P. heldreichii had higher contents of C 19 , C 21 , and C 22 , while those of P. peuce had higher content of C 29 . These results are not in accordance with PCA analysis of terpenes, where P. nigra was closer to P. heldreichii , while P. peuce was separated. In n ‐alkane analysis, where Picea omorika was the third species, P. heldreichii and P. peuce partially overlapped.…”

“…However, CA showed the weakest grouping of populations within the species compared to other multivariate methods. It may be concluded that position of studied pines on the basis of n ‐alkane composition neither was in accordance with infrageneric classification nor with recent molecular and terpene investigations …”

“…of section Pinus . Recent researches also confirmed the displacement of P. heldreichii to Mediterannean pines (subsection Pinaster ), which are opposite of earlier statement that classified P. heldriechii in intermediate position between hard and soft pines.…”

Coalescent‐based species delimitation in North American pinyon pines using low‐copy nuclear genes and plastomes

“…Pinus discolor produces a higher quantity of these monoterpenes compared to P. johannis, which has them in trace amounts (Zavarin and Snajberk, 1986). Traditionally, terpenes have been used as a character to differentiate species of pines (Mitić et al, 2017) but the differences are not always significant at the species level because the composition of monoterpenes differs very little among species or there is great variability in composition of monoterpenes within species (Zavarin et al, 1980;Snajberk and Zavarin, 1986;Zavarin and Snajberk, 1987).…”