Identification and regulation of host genes related to Rice stripe virus symptom production.

Viral infections cause plant chlorosis, stunting, necrosis or other symptoms. The down-regulation of chloroplast-related genes (Ch RGs) is assumed to be responsible for chlorosis., We identified the differentially expressed genes ( DEGs) in Rice stripe virus ( RSV)-infected Nicotiana benthamiana, and examined the contribution of 75 down-regulated DEGs to RSV symptoms by silencing them one by one using Tobacco rattle virus ( TRV)-induced gene silencing., Silencing of 11 of the 75 down-regulated DEGs caused plant chlorosis, and nine of the 11 were Ch RGs. Silencing of a down-regulated DEG encoding the eukaryotic translation initiation factor 4A ( eIF4A) caused leaf-twisting and stunting that were visible on RSV-infected N. benthamiana. A region of RSV RNA4 was complementary to part of eIF4A mRNA and virus-derived small interfering (vsi RNAs) from that region were present in infected N. benthamiana. When expressed as artificial micro RNAs, those vsi RNAs could target Nbe IF4A mRNA for regulation., We provide experimental evidence supporting the association of Ch RGs with chlorosis and show that eIF4A is involved in RSV symptom development. This is also the first report demonstrating that si RNA derived directly from a plant virus can target a host gene for regulation. [ABSTRACT FROM AUTHOR]