Lactuca georgica Grossh. is a wild species belonging to the secondary lettuce gene pool: additional evidence, obtained by KASP genotyping

Abstract

This work evaluated the genetic relationships between 442 single-seed descent (SSD) accessions, representing eight Lactuca spp., including ve wild Lactuca relatives (WLRs) (Lactuca georgica, L. altaica, L. saligna, L. serriola, L. aculeata), L. tuberosa, L. undulata, and the domesticated lettuce, L. sativa, most of them (437) representing a core subset of the Institute of Evolution's Wild Lettuce Gene Bank (IoE's WLGB) collection. The analysis was performed by pro ling 115 single-nucleotide polymorphism (SNP) markers by means of the uorescent KASP genotyping assay. The KASP marker fragments were scored as either allele "A" or allele "B", that were used across analyses as bi-allelic data, but included relatively a lot of U-scores, i.e., an absence of the speci c sequence, that were treated as missing data. Often U-scores were speci c for a certain species. Data analysis of the ve WLRs showed that allele frequencies of 103 (97.2%) out of 106 differentiating loci varied signi cantly among the species, where 59.7% of the KASP marker diversity was between species. A neighbor-network analysis between samples belonging to the ve WLRs and a single L. sativa cv. clearly clustered all 430 samples in accordance with their taxonomic determination. The results obtained here via multiple complementary analyses of large natural populations and individuals for germplasm variation, question assignment of L. georgica to the primary lettuce gene pool (LGP1). Together with our previous results obtained using TRAP markers, and hybridization experiments, we conclude that L. georgica is a constituent of the LGP2.

Natural variation in seed coat color in lettuce and wildLactucaspecies

“…The Lactuca tree was then annotated based on reported germplasm pools that underly genetic variation of L. sativa [17]. L. georgica was changed to the secondary germplasm pool based on [28]. The tree was further annotated into two clades [18].…”