Genotyping-by-Sequencing for Species Delimitation in Lemna Section Uninerves Hegelm. (Lemnaceae)

Bog M, Xu S, Himmelbach A, Brandt R, Wagner F, Appenroth K, Sree KS

Abstract

Lemna section Uninerves presently consists of three species, Lemna minuta Kunth (common synonyms L. minima Chev., L. minuscula Herter), L. valdiviana Phil., and L. yungensis Landolt. The species L. yungensis was discovered by E. Landolt about 20 years ago. He mentioned that although this species specifically grows on wet rocks, it is closely related to L. valdiviana and is morphologically very similar to the other two species in this section. Therefore, we started with molecular taxonomic studies of this section by using genotyping-by-sequencing (GBS). It was found that L. minuta could be clearly separated from L. valdiviana/L. yungensis; however, no separation was found between L. valdiviana and L. yungensis, despite the fact that they occupy different ecological niches. These data revealed that L. yungensis is identical to L. valdiviana on the genetic basis. Based on these results, we suggest that the name Lemna yungensis should be synonymised. As the description of L. valdiviana Phil. is the older one, this would be the valid common name for all the clones defined before as L. valdiviana and L. yungensis. This decision reduces the number of Lemnaceae species to 36. Testing the method of GBS with the genus Lemna demonstrated its superiority in comparison with barcoding based on PCR amplifications.