Identification of host factors potentially involved in RTM-mediated resistance during potyvirus long distance movement

Abstract

The long distance movement of potyviruses is a poorly understood step of the viral cycle. Only factors inhibiting this process, referred to as "Restricted TEV Movement" (RTM), have been identified in Arabidopsis thaliana. On the virus side, the potyvirus coat protein (CP) displays determinants required for long-distance movement and for RTM-based resistance breaking. However, the potyvirus CP was previously shown not to interact with the RTM proteins. We undertook the identification of Arabidopsis factors which directly interact with either the RTM proteins or the CP of lettuce mosaic virus (LMV). An Arabidopsis cDNA library generated from companion cells was screened with LMV CP and RTM proteins using the yeast two-hybrid system. Fourteen interacting proteins were identified. Two of them were shown to interact with CP and the RTM proteins suggesting that a multiprotein complex could be formed between the RTM proteins and virions or viral ribonucleoprotein complexes. Co-localization experiments in Nicotiana benthamiana showed that most of the viral and cellular protein pairs co-localized at the periphery of chloroplasts which suggests a putative role for plastids in this process.

Genome‐wide association study reveals new loci involved in Arabidopsis thaliana and Turnip mosaic virus (TuMV) interactions in the field

“…The Arabidopsis cDNA library generated from companion cells was screened with LMV CP and RTM3 proteins using the yeast two-hybrid system. Only one prey protein was found to interact with RTM3, but a multiprotein complex was suggested to be formed between the RTM proteins and virions or viral ribonucleoprotein complexes (Sofer et al, 2017). It is interesting to note that in apricot, a locus encompassing genes encoding MATH domain proteins has been also associated with the response to PPV (Zuriaga et al, 2013(Zuriaga et al, , 2018.…”

SIEVE ELEMENT-LINING CHAPERONE1 Restricts Aphid Feeding on Arabidopsis during Heat Stress

“…SLI1 might require one or more phloem-specific factors for its association with mitochondria, possibly via a comparable mechanism as its homolog, RTM2. Sofer et al (2017) showed in a transient expression assay that RTM2 requires BRANCHED-CHAIN AMINOTRANSFERASE4 (BCAT4) for its recruitment to the chloroplast periphery. Without BCAT4, RTM2 formed small aggregates in the cytoplasm of Nicotiana benthamiana epidermal cells.…”

Defenses against Virus and Vector: A Phloem-Biological Perspective on RTM- and SLI1-Mediated Resistance to Potyviruses and Aphids

“…This led to the hypothesis that the RTM gene complex prevents long-distance transport via the sequestration or obstruction (of certain domains) of the viral CP. So far, however, no interactions have been observed between RTM proteins and the CP or the VPg of LMV [45]. Yeast-two hybrid assays only have revealed monomeric and multimeric interactions of RTM1 and RTM3, but not of RTM2 [36].…”

“…Therefore, a larger multimeric protein complex has been postulated, containing additional yet unidentified host proteins, which would (indirectly) link the RTM proteins to viral CP. During a recent large yeast-two hybrid screen of a companion cell cDNA expression library [45] LATERAL ROOT PRIMORDIUM 1 (LRP1), BRANCHED-CHAIN AMINOTRANSFERASE4 (BCAT4) and FIBRILLIN 1B (FBN1b) have been identified to interact with both RTM proteins and LMV CP. These proteins are involved in plant development, aliphatic glucosinolate biosynthesis and plastid lipids, respectively.…”

“…Since the N-terminus of the CP has been shown to play a key role in RTM resistance [44], a third possibility could involve an interference, by RTM, on the assembly or trafficking of a virus movement complex. However, so far, evidence is lacking that points towards the formation of a multimeric protein complex in which viral CP and RTM proteins (indirectly) interact [45], and which would support this third possible idea.…”