A high-quality draft genome for Melaleuca alternifolia (tea tree) - a new platform for evolutionary genomics of myrtaceous terpene-rich species

Melaleuca alternifolia (tea tree) is an Australian native tree, which is the source of a renowned terpene-rich essential oil used in therapeutic and cosmetic products around the world. Tea tree has been cultivated and bred in Australia since the 1990’s, and because of its economic importance, along with its Eucalyptus and Corymbia spp relatives, is one of the most extensively studied members of the Myrtaceae family for genetics and biochemistry of terpene biosynthesis. Here, a high-quality de novo genome assembly using PacBio and Illumina sequencing data is reported as a platform for comparative genomics in the Myrtaceae. The genome was assembled into 3,128 scaffolds with a total length of 362 Mb (N50 = 1.9 Mb) and had significantly higher contiguity than a previously reported assembly (N50 = 8.7 Kb) based on short Illumina paired-end reads. A total of 37,226 protein-coding genes were predicted, using a homology-based, RNAseq evidence-based and ab initio prediction approach. Genome assembly and annotation exhibited high completeness scores of 98.1% and 89.4%, respectively, when compared to the eudicot BUSCO database. The contiguity of the sequence was sufficient to reveal extensive gene order conservation and detection of chromosomal rearrangements in alignments with E. grandis and C. citriodora genomes. This new genome provides an enhanced resource to investigate the genome structure and gene family evolution of M. alternifolia, which will enable further comparative genomic studies in the family of Myrtaceae, and help to elucidate the genetic foundations of economically valuable traits in this essential oil crop.The reviewed version of this article has been published in: Julia Voelker, Mervyn Shepherd, Ramil Mauleon, A high-quality draft genome for Melaleuca alternifolia (tea tree): a new platform for evolutionary genomics of myrtaceous terpene-rich species, Gigabyte, 1, 2021 https://doi.org/10.46471/gigabyte.2