Resistance to Viruses of Potato and their Vectors

Palukaitis, Peter The Korean Society of Plant Pathology 2012 Plant Pathology Journal Vol.28 No.3

Potato (Solanum tuberosum) is one of the most important food crops worldwide and yields of potato can be affected by virus infection. While more than 40 viruses have been found in potato, only nine viruses (potato leafroll virus, potato viruses A, M, S, V, X and Y, potato moptop virus and tobacco rattle virus) and one viroid (potato spindle tuber viroid) have a significant economic impact on potato, worldwide. This review describes the geographical distribution of the most important viruses infecting potato and the genes for resistance or tolerance that have been identified against these various infectious agents. In some cases such resistance genes have been found only in other Solanum species. Few genes for resistance to the vectors of these viruses have been obtained and even fewer have been deployed successfully. However, transgenic resistance in potato has been achieved against seven of these disease agents.

The Road to RNA Silencing is Paved with Plant-Virus Interactions

Palukaitis, Peter The Korean Society of Plant Pathology 2011 Plant Pathology Journal Vol.27 No.3

RNA silencing has had a large impact on biology in general, as well as on our understanding of plant-pathogen interactions, especially interactions between plants and viruses. While most of what we know about the mechanism of RNA silencing was deduced in the last 12 years, many of the interactions between plants and viruses, as well as virus-virus interactions in plants, which we now know are manifestations of RNA silencing, were the subject of decades of work from numerous laboratories. These laboratories were examining the nature and extent of phenomena such as recovery from infection, the formation of dark green islands resistant to re-infection, synergy between unrelated viruses and cross-protection between related viruses, all first described in the late 1920s. In this review, the relationships between these phenomena and their place in the defense mechanism we call RNA silencing will be described, to show how they are all linked.

Resistance to Turnip Mosaic Virus in the Family Brassicaceae

Peter Palukaitis,Su Kim 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.1

Resistance to diseases caused by turnip mosaic virus (TuMV) in crop species of the family Brassicaceae has been studied extensively, especially in members of the genus Brassica. The variation in response observed on resistant and susceptible plants inoculated with different isolates of TuMV is due to a combination of the variation in the plant resistome and the variation in the virus genome. Here, we review the breadth of this variation, both at the level of variation in TuMV sequences, with one eye towards the phylogeny and evolution of the virus, and another eye towards the na- ture of the various responses observed in susceptible vs. different types of resistance responses. The analyses of the viral genomes allowed comparisons of pathotyped viruses on particular indicator hosts to produce clusters of host types, while the inclusion of phylogeny data and geographic location allowed the formation of the host/ geographic cluster groups, the derivation of both of which are presented here. Various studies on resistance determination in particular brassica crops sometimes led to further genetic studies, in many cases to include the mapping of genes, and in some cases to the actual identification of the genes. In addition to summarizing the results from such studies done in brassica crops, as well as in radish and Arabidopsis (the latter as a poten- tial source of candidate genes for brassica and radish), we also summarize work done using nonconventional approaches to obtaining resistance to TuMV.

Satellite RNAs and Satellite Viruses

APS Press 2016 Molecular plant-microbe interactions Vol.29 No.3

Cucumber Mosaic Virus 1a Protein Interacts with the Tobacco SHE1 Transcription Factor and Partitions between the Nucleus and the Tonoplast Membrane

Ju-Yeon Yoon,Peter Palukaitis 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.2

The transcription factor SHE1 was identified as an interacting partner with the cucumber mosaic virus (CMV) 1a protein in the yeast two-hybrid system, by a pull-down assay, and via bimolecular fluorescent complementation. Using fluorescent-tagged proteins and confocal microscopy, the CMV 1a protein itself was found distributed predominantly between the nu- cleus and the tonoplast membrane, although it was also found in speckles in the cytoplasm. The SHE1 protein was localized in the nucleus, but in the presence of the CMV 1a protein was partitioned between the nucleus and the tonoplast membrane. SHE1 expression was in- duced by infection of tobacco with four tested viruses: CMV, tobacco mosaic virus, potato virus X and potato virus Y. Transgenic tobacco expressing the CMV 1a protein showed constitutive expression of SHE1, in- dicating that the CMV 1a protein may be responsible for its induction. However, previously, such plants also were shown to have less resistance to local and systemic movement of tobacco mosaic virus (TMV) expressing the green fluorescent protein, suggesting that the CMV 1a protein may act to prevent the function of the SHE1 protein. SHE1 is a member of the AP2/ERF class of transcription factors and is conserved in sequence in several Nicotiana species, although two clades of SHE1 could be discerned, including both different Nicotiana species and cultivars of tobacco, varying by the pres- ence of particular insertions or deletions.

Sequence comparisons of global chrysanthemum stunt viroid variants: multiple polymorphic positions scattered through the viroid genome.

Yoon, Ju-Yeon,Palukaitis, Peter M. Nijhoff ; Kluwer Academic Publishers 2013 Virus genes Vol.46 No.1

<P>The nucleotide sequences of cDNA clones of three chrysanthemum stunt viroid (CSVd) isolates (one each from the USA, China, and Australia) were determined and analyzed. The sequences of CSVd cDNA clones of the US and Australian isolates were both quasi-species, while the cDNA clones of the Chinese isolate contained only a single variant. A comparison of the nucleotide sequences of 117 isolates and cDNA clones obtained from 16 countries showed that in some cases identical CSVd isolates were found in several countries and from multiple locations within the same country. CSVd isolates differed as much in sequence between countries as within countries. Sequence variation was observed at 103 sites scattered through the CSVd genome, and was not associated predominantly with a single variable region, as was the case with several other viroids. While some sequence changes were associated with CSVd found in other host species, it is unknown if these changes are required for infection of those species.</P>

The Use of a Tobacco mosaic virus-Based Expression Vector System in Chrysanthemum

박민주,백이슬,윤주연,Peter Palukaitis 한국식물병리학회 2017 Plant Pathology Journal Vol.33 No.4

Chrysanthemums (Chrysanthemum morifolium) are susceptible to tobacco mosaic virus (TMV). TMV-based expression vectors have been used in high-throughput experiments for production of foreign protein in plants and also expressing green fluorescent protein (GFP) to allow visualization of TMV move-ment. Here, we used TMV expressing the GFP to examine the infection of chrysanthemum by a TMV-based expression vector. Viral replication, movement and GFP expression by TMV-GFP were verified in upper leaves of chrysanthemums up to 73 days post inoculation (dpi) by RT-PCR. Neither wild-type TMV nor TMV-GFP induced symptoms. GFP fluorescence was seen in the larger veins of the inoculated leaf, in the stem above the inoculation site and in petioles of upper leaves, although there was no consistent detec-tion of GFP fluorescence in the lamina of upper leaves under UV. Thus, a TMV-based expression vector can infect chrysanthemum and can be used for the in vivo study of gene functions.

Mapping Analysis of Virus Sequences Affecting Host Range and Movement of Cucumber Mosaic Virus

Ki Hyun Ryu,Peter Palukaitis 한국식물병리학회 2000 Plant Pathology Journal Vol.16 No.2

Cucumber mosaic virus 2a polymerase and 3a movement proteins independently affect both virus movement and the timing of symptom development in zucchini squash

Choi, Seung Kook,Palukaitis, Peter,Min, Byoung Eun,Lee, Mi Yeon,Choi, Jang Kyung,Ryu, Ki Hyun Microbiology Society 2005 The Journal of general virology Vol.86 No.4

<P>The basis for differences in the timing of systemic symptom elicitation in zucchini squash between a pepper strain of Cucumber mosaic virus (Pf-CMV) and a cucurbit strain (Fny-CMV) was analysed. The difference in timing of appearance of systemic symptoms was shown to map to both RNA 2 and RNA 3 of Pf-CMV, with pseudorecombinant viruses containing either RNA 2 or RNA 3 from Pf-CMV showing an intermediate rate of systemic symptom development compared with those containing both or neither Pf-CMV RNAs. Symptom phenotype was shown to map to two single-nucleotide changes, both in codons for Ile at aa 267 and 168 (in Fny-CMV RNAs 2 and 3, respectively) to Thr (in Pf-CMV RNAs 2 and 3). The differential rate of symptom development was shown to be due to differences in the rates of cell-to-cell movement in the inoculated cotyledons, as well as differences in the rate of egress of the virus from the inoculated leaves. These data indicate that both the CMV 3a movement protein and the CMV 2a polymerase protein affect the rate of movement of CMV in zucchini squash and that these two proteins function independently of each other in their interactions with the host, facilitating virus movement.</P>

Resistance to multiple viruses in transgenic tobacco expressing fused, tandem repeat, virus-derived double-stranded RNAs.

Chung, Bong Nam,Palukaitis, Peter M. Nijhoff ; Kluwer Academic Publishers 2011 Virus genes Vol.43 No.3

<P>Transgenic tobacco plants expressing fused, tandem, inverted-repeat, double-stranded RNAs derived either from the three viruses [potato virus Y (PVY), potato virus A (PVA), and potato leafroll virus (PLRV)] or the five viruses [PVY, PVA, PLRV as well as tobacco rattle virus (TRV), and potato mop-top virus (PMTV)] were generated in this study to examine whether resistance could be achieved against these three viruses or five viruses, respectively, in the same plant. The transgenic lines were engineered to produce 600- or 1000-bp inverted hairpin transcripts with an intron, in two orientations each, which were processed to silencing-inducing RNAs (siRNAs). Fewer lines were regenerated from the transformants with either 1000-bp inverted hairpin transcripts, or a sense-intron-antisense orientation versus antisense-intron-sense orientation. Resistances to PVA and two strains of PVY (-O and -N) were achieved in plants from most of lines examined, as well as resistance to co-infection by a mixture of PVY-O and PVA, applied to the plants by either rub inoculation or using aphids. This was regardless of the orientation of the inserted sequences for the 600-bp insert lines, but only for one orientation of the 1000-bp insert lines. The lines containing the 1000-bp inserts also showed resistance to infection by TRV inoculated by rub inoculation and PMTV inoculated by grafting. However, all the lines showed only low-to-moderate (15-43%) resistance to infection by PLRV transmitted by aphids. The resistances to the various viruses correlated with the levels of accumulation of siRNAs, indicating that the multiple resistances were achieved by RNA silencing.</P>