Lettuce (Asteraceae; Lactuca spp.)

North American Continent - A New Source of Wild Lactuca Spp. Germplasm Variability for Future Lettuce Breeding

“…Morphological assessments of 231 L. serriola seed samples were performed during the course of their regeneration (during the vegetative period from April to October 2009) in a greenhouse under controlled conditions (Lebeda et al, 2007). Assessments included 12 quantitative and qualitative characters of stems (e.g., form of branching, character of indumentum), rosette and cauline leaves (e.g., rosette formation, depth of leaf incisions), inflorescences and flowers (e.g., inflorescence type, anthocyanin presence in bracts), following published descriptor lists for wild Lactuca species (Doležalová et al, 2002a(Doležalová et al, , 2003.…”

“…This group is characterized by the consistent presence of the haploid chromosome number, n=17, making it both geographically and genetically isolated (Lebeda et al, 2007). These species are of amphidiploid origin, resulting from interspecific crossing, chromosome doubling (perhaps through unreduced-gamete formation), and subsequent hybrid stabilization (or diploidization) (Feráková, 1977).…”

“…The wild relatives of agricultural crops conserved in genebank collections constitute a broad genetic base that can provide essential materials for plant breeding (Lebeda et al, 2007). In many cases, the primary genepools of cultivated crops have been carefully examined but have been found deficient as sources of specific traits important for breeding.…”

“…Those deficiencies have motivated expeditions to regions of high agrobiodiversity and increased emphasis on the utilization of wild crop relatives (Hajjar and Hodgkin, 2007;Lebeda et al, 2009a). Newly collected germplasm accessions serve as donors of new resistance genes against diseases, pests, and abiotic stresses, as well as of genes for improving physiological and quality traits (Lebeda et al, 2007). During the last 30 years, there has been considerable progress in the collection, characterization, and practical application of Lactuca L. germplasm collections, as well as in filling in gaps in our knowledge about the biology and ecology of many Lactuca species (Lebeda et al, 2009a).…”

Incidence of lettuce downy mildew (Bremia lactucae) and powdery mildew (Golovinomyces cichoracearum) in natural populations of prickly lettuce (Lactuca serriola)

“…From an ecological point of view, prickly lettuce can be considered as r-strategist, given that it is an invasive pioneer plant species which readily colonises new habitats. L. serriola is part of the primary gene-pool of the genus Lactuca L. It is closely related to cultivated lettuce and is considered as its ancestor (de Vries 1997;Lebeda et al 2007). Because of their large genetic diversity, plant progenitors like L. serriola are used for studies of resistance to diseases (Lebeda et al 2008) and lettuce breeding .…”