Many chloroplast ribosomal protein genes were strongly down-regulated in a related study in response to co-infection with CTV-B6 and “Candidatus Liberibacter asiaticus,” causal agent of citrus huanglongbing (Bové, 2006; submitted), and were also greatly repressed in response to CTV-B2/CTV-B6, including RPS17, RPL9, RPL17, and RPL18 (Table 2). This evidence concerns the gene RPL18 and coinfection.