Phylogenetic Analyses Of Colutea ( Leguminosae: Galegeae)

The genus Colutea belong to the tribe Galegeae in the Leguminosae and included about 28 species in the Northern Hemisphere. Colutea is distributed in the central Asian and the Mediterranean Region, while C. delavayi is endemic to China. The aim of the present study is to evaluate the separate disjunction status of Colutea in order to clarify the systematic relationships, and to make a taxonomic revision based on the evidence from macromorphology, SEM observations of surface sculpturing of pod, and cytological and molecular studies. A proposal of Sinocolutea W.G. Sun, Z.M. Li & H. Sun(Fabaceae, Galegeae): A new genus endemic to the Jinshajiang River from Hengduan Mountains, SW China. 1. CytologyKaryomorphological studies on C. delavayi, C. arborescens and C. orientalis have been carried out, in which the karyotype data of C. delavayi is initially broadcasted. The karyotype of C. delavayi is 2n = 2x = 16 = 16 m, of C. oriental is 2n = 2x = 16 = 12 m + 4sm, and of C. arborescens is 2n = 2x = 16 = 10 m + 6sm, whose chromosome number is 2n=16, which is consistent with previous reports. Among this genus plants, comparing with the existing cytological materials of Colutea property, the idea that C. delavayi is a relatively primitive group is proposed. 2. SEM observation of surface sculpturing of podPods surface sculpturing of 6 samples representing 5 species of Colutea, Sphaerophysa and identification of errors species where investigated under scanning electronic microscopy(SEM). The seeds of Colutea are narrowly ovoid in shape, episperm are black, tan or brown and with smooth surface. But the C. delavayi is different from the sampled remaining species Colutea. The characters of seeds, such the length, the color on the surface and the ornamentation on seed coat, are of great significance in distinguishing the C. delavayi from Colutea. Besides, C. delavayi with the highest level of diversification in seed morphology, which may be correlated to the more advanced adaptation in the Hengduan Mountains. 3. Molecular phylogenyWith the available data from Gen Bank and by using plastids DNA(psb A-trn H、trn L-F、mat K & rpl32-trn L) and nr DNA ITS sequence information, a phylogenetic analysis was carried out on 43 samples representing 10 genera and 31 species of the Galegeae(Fabaceae). Using maximum parsimony, maximum likelihood, and Bayesian inferences, all the results supported the polyphyletic of the Colutea, and three clades of the genus Colutea. The results indicated that, C. delavayi is not belong to Colutea and it`s the most basal taxon. We approve Oreophysa microphylla(Jaub. & Spach) Browicz incorporate into Colutea as C. microphylla. 4. Taxonomic revision of the generaIn summary, pieces of evidence from morphology, cytology, and molecular phylogeny all support Colutea delavayi being distinct from Colutea in Galegeae. We draw the conclusion that the recognition of the species as a separate genus, described as Sinocolutea below, is the appropriate taxonomic conclusion. And at the same time, previous deduction, that is, Sinocolutea delavayi is the relict plants of Tethys Origin.