Complete Chloroplast Genomes of Saccharum giganteum, Saccharum longisetosum, Cleistachne sorghoides, Sarga timorense, Narenga porphyrocoma and Tripsacum dactyloides. Comparisons with ITS phylogeny and Placement within Saccharum.

Abstract

The first complete chloroplast and Internal Transcribed Sequence (ITS) cassette sequences for the species: Saccharum giganteum, Saccharum longisetosum, Cleistachne sorghoides, Saccharum narenga and Tripsacum dactyloides are presented. Corresponding sequences for a new isolate of Sarga timorense were assembled. Phylogenetic analyses place S. giganteum, S. longisetosum and S. narenga within the Saccharinae but distinct from Saccharum, whilst C. sorghoides emerges as a member of genus Sarga and Tripsacum datyloides as a member of the Tripsacinae. Comparison of chloroplast and ITS phylogenies reveal complex reticulate evolution within the Saccharinae, with S. giganteum, S. longisetosum and S. narenga, despite having the same base chromosome count (15) having different evolutionary origins; making them members of different genera and not members of genus Saccharum. The importance of reticulate evolution in the origins of Andropogoneae, particularly the Saccharinae and the unique positions of Saccharum and Miscanthus is discussed.