The differential expression patterns of ZIP1, ZIP4, and ZIP5 in response to co-infection by CTV-B2/CTV-B6 and infection by CTV-B2 alone is probably due to severe, virulent CTV-B6, which affects the plant profoundly, inducing chlorosis of leaves, collapse of phloem and root decline. The gene discussed is SLC39A5; the disease is coinfection.