Chloroplast genome of serrated tussock {Nassella trichotoma): structure and evolution

摘要

The genus Nassella contains many economically and environmentally important weed species in Australia, such as Nassella trichotoma (Nees) Hack, ex Arechav. (serrated tussock) and Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass), which are both Weeds of National Significance (WoNS). Availability of Nassella chloroplast genome sequences can provide a versatile tool for identifying novel gene targets for DNA barcoding of these weeds species. We report here the first chloroplast genomeof Nassella (N. trichotoma) obtained through de novo assembly of Illumina paired-end reads produced by total DNA sequencing. The /V. trichotoma chloroplast genome is 112,102 bp in size, encodes 140 genes including 99 protein-coding genes, 37 tRNA genes and 4 ribosofmal RNA genes. The total size of intergenic regions within the genome is up to 48,764 bp. The total GC content of the genome is 37.88%, which is relatively lower than that of the reported genomes within the Stipeae tribe. A comparison of thischloroplast genome with other Stipeae chloroplast genomes (Oryzopsis asperifolia Michx., Piptochaetium aven-aceum (L.) Parodi, Achnalheriim hymenoides Roem. & Schult., Stipa lipskyi Roshev. and Stipa purpurea Griseb.) provides new insights into their chloroplast genome evolution. Our future work will report genomes of other Nassella species as a means to identify novel DNA barcode regions useful for distinguishing these species.