Development of an expression assay probing the ability of the P6 effector of Cauliflower mosaic virus expressed in trans to support virion accumulation.
J. SCHOELZ (1), Y. Zhang (1), A. Mustafa (1), R. Nelson (2), C. Angel (3) (1) University of Missouri, U.S.A.; (2) The Samuel Roberts Noble Foundation, U.S.A.; (3) Cenicana, Colombia

The P6 effector of Cauliflower mosaic virus (CaMV) is an elicitor of plant defenses in resistant hosts and disease symptoms in susceptible hosts, as well as functioning as a suppressor of salicylic acid-mediated defenses and gene silencing. The P6 effector has essential roles in formation of the virion factory, translation of the polycistronic 35S RNA, and intracellular movement on microfilaments for delivery of virions to the plasmodesmata.  Subcellular localization studies of ectopically-expressed P6 tagged with GFP (P6-GFP) have revealed that it is found in both the cytoplasm and nucleus, forming associations with the endoplasmic reticulum, microfilaments, microtubules, and plasmodesmata. In this study, we show that P6 or P6-GFP expressed in trans is able to support replication and encapsidation of newly synthesized viral DNA. The P6 constructs were co-agroinfiltrated into Nicotiana benthamiana with a CaMV clone that contained a lethal frameshift in the P6 gene.  Virions isolated at seven days after agroinfiltration were treated with DNaseI to remove any unencapsidated DNA before the coat protein was stripped off to release the virion DNA.  A PCR assay showed that viral DNA could be amplified when P6 or P6-GFP was co-agroinfiltrated with the defective CaMV isolate.  Furthermore, electron micrographs showed that virions could be recovered from the co-agroinfiltrated plant tissues, proving that the P6-GFP effector can support the formation of the virion factory.

Abstract Number: P7-208
Session Type: Poster