New data and phylogenetic placement of the enigmatic Old World lupin: Lupinus mariae-josephi H. Pascual

Abstract

Lupinus mariae-josephi H. Pascual is an intriguing lupin species recently discovered in the Mediterranean region. New data from seed coat micromorphology, cytology, and DNA sequences were generated in order to extend our knowledge on this species and to examine its evolutionary relationships within Lupinus. This species shows morphological similarities with the Mediterranean smooth seeded species of sections Micranthi and Lutei. It shares the same chromosome number 2n = 52 with the latter Old World taxa, but also with unifoliolate lupins from Florida. Besides, L. mariae-josephi exhibited a seed coat micromorphology “intermediate” between the rough and the smooth seed coat types. Phylogenetic analyses using ITS and ETS nrDNA spacers, and the LEGCYC1A locus supported L. mariae-josephi as a distinct Old World line, placed out of the Scabrispermae, but without clear placement amongst the Mediterranean smooth-seeded lineages. Unexpectedly, LEGCYC1A data revealed phylogenetic affinities between L. mariae-josephi and L. villosus, a unifoliolate North American lupin that might have experienced a reticulated evolutionary process. All together, the data underline the phylogenetic interest of L. mariae-josephi in Lupinus and the need of additional investigations in order to definitely elucidate its enigmatic status. Moreover, as L. mariae-josephi is one of the rare Old World lupins strictly restricted to poor basic soils, it opens new perspectives of ecological and agronomic interests in the wide areas of poor calcareous soils in the Mediterranean region.