The Morphological and Genetic Variation of a Species of Lettuce (Lactuca undulata Ledeb.): Geographically Widespread but Locally Endangered

Lactuca undulata Ledeb. (Asteraceae) is an annual plant that has valuable compounds such as caffeic acid and its derivatives. This study aims to understand if there is detectable genetic diversity in the Iranian populations of L. undulata. For this purpose, the diversity of five L. undulata populations collected from different regions of Iran was evaluated based on the morphological characteristics and ISSR markers. A common garden experiment was conducted to assess the morphological variation of five L. undulata populations. The results of the study of morphological features showed that most of the studied traits have a high diversity among populations. In the PCoA performed, five populations of L. undulata were identified based on their morphological characteristics. In genetic analyses, using ISSR markers, a total of 60 bands were produced using four primers. The percentage of total polymorphism was 100% and no monomorphic band was obtained. The Nei gene diversity index (H) and Shannon diversity index (I) indicated high genetic diversity (0.24) in the populations. Analysis of molecular variance (AMOVA) showed that 73% of the genetic diversity was within the populations and another 27% was among the populations. The highest and the lowest genetic diversity were observed in Cheshmeh Ali and Qom populations, respectively. PCoA nearly separated genetically different populations into distinct groups. Five L. undulata populations were found to differ significantly in their morphological and genetic polymorphism. The studied populations were found in highly degraded habitats with a limited number of individuals. Degradation and loss of habitats are the major concerns in determining the conservation status of the species in general and at the population level in particular.