Variation of sesquiterpene lactone contents in Lactuca altaica natural populations from Armenia

Abstract

In recent years we initiated extensive studies on the characterization of the population structure of wild Lactuca relatives (WLRs) originating from their center of origin and diversity in Southwest Asia. A comparative phytochemical study of nine sesquiterpene lactones in natural populations of the wild lettuce L. altaica Fisch. & C.A. Mey. (Asteraceae) was performed, based on 22 plants, representing seven original individual seed samples derived from three localities representing three regions in Armenia. The compounds were profiled and quantified in leaves and roots of the plants, grown in a controlled glasshouse. The contents of major sesquiterpene lactones, that including the following eight guaianolides: cichorioside B, lactucin, 11β,13-dihydrolactucin, crepidiaside B, 8-deoxylactucin, jacquinelin, lactucopicrin/11β,13-dihydrolactucopicrin, as well as the germacranolide glucoside – lactuside A, were estimated by HPLC/PDA. The L. altaica plants could be characterized by the occurrence of lactuside A in their roots, and the mixture of lactucopicrin/11β,13-dihydrolactucopicrin in both their roots and leaves by relatively high amounts, similarly to results obtained for three commercial cultivars of L. sativa. The total content of sesquiterpene lactones in the roots was significantly higher than that in the leaves. This study is likely the first report of detailed screening of L. altaica natural populations and individuals, even by low sample size, for any trait. Species within the primary lettuce gene pool, should be considered as an attractive source of germplasm in further research and improvement of cultivated lettuce, Lactuca sativa L. While using interspecific hybridization in order to elevate the sesquiterpene levels in cultivated lettuces, the lactones quality (profile) and quantity, as well as the cross-ability level of the wild Lactuca spp. with the crop and fertility of the obtained offspring should be considered.