Phylogenetic relationships and dysploidy in Capsicum: Evidence from DNA sequences and other multidisciplinary data

SEHR E. M.; BARFUSS, M.; BARBOZA G. E.; MOSCONE, E. A.; SAMUEL, R.; EHRENDORFER, F.

Vienna

Congreso; Second BioSyst-EU Conference; 2013

BioSyst European Societies

DNA sequences of two plastid markers (trnH-psbA, matK) and of the single copy nuclear gene waxy from two outgroup genera and 23 taxa of Capsicum(Solanaceae) are quite congruent. They support earlier reports on Lycianthes as the only other member of tribe Capsiceae in the New World and as link to other Solanoideae genera. Capsicum is clearly monophyletic, entirely diploid and includes four clades (or grades) with two different chromosome base numbers, x = 12 and 13. The strict consensus tree from the ML analysis of the combined plastid markers and the only ML phyogram from the nuclear gene waxy clearly place the clade of C. rhomboideum(1), centred in NW S-America  with x = 13 in a most basal position within Capsicum and closest to the wide-spread Lycianthes (x = 12). Both share the plesiomorphic characters of small and undifferentiated innermost mesocarp cells and the complete absence of pungent capsacinoids, otherwise common in Capsicum. This suggests that the origin of the genus was coupled with a dysploid change from x = 12 ?¨ 13. Clearly related to (1) is the clade of C. villosum (2a) which includes the somewhat aberrant C. campylopodium (2b). This clade is  centred in SE-Brazil,  also  has x = 13, but already exhibits the apomorphic giant innermost mesocarp cells and capsacinoids. The closely following  grade (3) with x = 12,  signals a phylogenetic return from x = 13 to   x = 12 within the genus, as supported by karyological and other data. This basal x = 12 grade (3) includes the species groups of C. flexuosum(3a) in central, C. parvifolium(3b) in northern S-America,  and C. coccineum(3c) + C. minutiflorum(3d) mainly in Bolivia. Grade (3) marks the phylogenetic transition towards the speciose x = 12 crown clade (4) of the genus which consists of the closely linked species groups of C. pubescens(4a),C. baccatum(4b), C. galapagoense (4c) and C. annuum(4d). These groups are not yet fully separated by crossing barriers and include all cultivated members of the genus.In retrospect: The morphological, anatomical, karyological, phytochemical  and molecular features of the genus Capsicum are closely related to its phylogenetic differentiation, help to reconstruct its assumed phases of eco-geographical expansion in the New World and contribute to its still provisional classification.