Draft genome sequence of 'Candidatus Phytoplasma asteris,’ strain SW86 associated with sandal spike disease (SSD)

The sandal spike disease (SSD), related to ‘Ca. Phytoplasma asteris’ (Aster Yellows group), poses a significant threat to Indian sandalwood (Santalum album L.), making it the second most expensive wood globally due to declining population density. The epidemiology of SSD and the nature of the pathogen remain poorly understood. The SW86 isolate, collected from the Marayoor Sandalwood Reserve, was chosen for genome sequencing subsequent to confirming its titer and enriching phytoplasma DNA. Genome sequencing, utilizing Illumina and Oxford Nanopore Technology platforms, enabled a targeted hybrid metagenomic assembly resulting in 20 scaffolds totaling 554,025 bp, housing 436 protein-coding genes, 27 tRNA, and 1 rRNA operon. The genome analysis highlighted specific gene distributions, emphasizing translation, ribosomal structure, and biogenesis, with 352 genes assigned to 18 functional categories. Additionally, 322 proteins received functional assignments in the KEGG database, emphasizing ‘Genetic Information Processing’ and ‘Environmental Information Processing’. Key potential pathogenicity factors, including signal peptide proteins and virulence proteins, were identified. Noteworthy findings include homologs of effectors genes like SAP11 and SAP05 and pathogenesis-related proteins, such as hemolysin III and SodA genes, in the SW86 genome. The duplicated cation-transporting P-type ATPase in the SW86 genome suggests a role in enhancing adaptability and contributing to the severity of SSD symptoms. This genome analysis provides crucial insights into the genomic features and potential virulence factors of ‘Ca. Phytoplasma asteris’ strain SW86, advancing our understanding of pathogenicity mechanisms and offering avenues for future disease management strategies in Indian sandalwood.