W559Annotation of the Lobolly Pine Megagenome
Annotation of the Lobolly Pine Megagenome
Date: Saturday, January 11, 2014
Time: 9:00 AM
Time: 9:00 AM
Room: Pacific Salon 6-7 (2nd Floor)
The largest genus in the conifer family Pinaceae is Pinus, with over 100 species. The size and complexity of their genomes (c. 20 to 40 Gb, 2n = 24) have delayed the arrival of a well-annotated reference sequence. The annotation for the first whole-genome shotgun assembly of loblolly pine (P. taeda L.), represents 20.15 Gb of sequence distributed across 14.4 million scaffolds. The MAKER2 annotation pipeline combined evidence-based alignments and ab initio predictions to generate 50,172 gene models, of which 15,653 were classified as high confidence. Alignments from PLAZA proteins, a comprehensive transcriptome, and other conifer EST resources served as evidence for gene prediction. The gene models were clustered with 13 other plant species, which resulted in a total of 20,717 gene families, of which 1,554 were predicted to be unique to conifers. Among the conifer gene families, 159 were composed exclusively of loblolly pine members. When compared with 24 fully sequenced plant species, the gene models from loblolly pine had the highest median and mean intron lengths. A total of 1,810 genes with primary introns between 20 and 158 Kbp in length were examined for intron mediated expression signals and repetitive content. Conifer genomes are full of repetitive DNA and the most significant contributions are from long terminal repeat (LTR) retrotransposons. The repetitive content was examined with a combined de novo and similarity approach to generate a genome-wide estimate of approximately 82%.
