Although potato virus Y (PVY) is one of the most economically important pathogens of potatoes in China, few studies have been carried out to characterize the virus in that country. Using reverse transcription-polymerase chain reaction (RT-PCR)-based genotyping developed previously, two types of recombinant PVY were identified in China for the first time. One resembled the European (Eu) type of potato tuber necrosis strain (Eu-PVY(NTN)), possessing three widely recognized recombinant joints (RJs 1-3) of the common strain (PVY(O)) and the Eu- type tobacco veinal necrosis strain (Eu-PVY(N)). The other, on the other hand, appeared to have only RJ1 and RJ2. The complete genome of a representative isolate, PVY-HN2, from the second type was subsequently sequenced. Comparison of the sequence of 'HN2' with those of PVY(O) and Eu-PVY(N) not only confirmed the recombinant nature of 'HN2' but also revealed the existence of three recombinant events in the isolate, similar to that in PVY(NTN)-Hun. However, the two isolates differed significantly at RJ1 (PVY(NTN)-Hun vs. HN2, nt 2419 vs. nt 2521) and RJ3 (PVY(NTN)-Hun vs. HN2, nt 9183 vs. nt 8572) and slightly at RJ2 (PVY(NTN)-Hun vs. HN2, nt 5844 vs. nt 5867). A primer pair was developed to facilitate the detection of the alternative RJ3. Using the newly and previously designed RJ primers, all targeted RJs were detected. Interestingly, tests of the available PVY samples indicated that two were doubly infected with both types of recombinant PVY, further confirming the effectiveness of the detection. Further analysis of these samples using enzyme-linked immunosorbent assay and bioassay revealed that 'HN2' possesses a PVY(O) serotype, a PVY(N) pathotype in tobacco and a PVY(NTN) pathotype in potato.

potato (Solanum tuberosum L.) is an important staple food worldwide. However, its growth has been heavily suppressed by salt stress. The molecular mechanisms of salt tolerance in potato remain unclear. It has been shown that the tetraploid potato Longshu No. 5 is a salt-tolerant genotype. Therefore, in this study we conducted research to identify salt stress response genes in Longshu No. 5 using a NaCl treatment and time-course RNA sequencing. The total number of differentially expressed genes (DEGs) in response to salt stress was 5508. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, it was found that DEGs were significantly enriched in the categories of nucleic acid binding, transporter activity, ion or molecule transport, ion binding, kinase activity and oxidative phosphorylation. Particularly, the significant differential expression of encoding ion transport signaling genes suggests that this signaling pathway plays a vital role in salt stress response in potato. Finally, the DEGs in the salt response pathway were verified by Quantitative real-time PCR (qRT-PCR). These results provide valuable information on the salt tolerance of molecular mechanisms in potatoes, and establish a basis for breeding salt-tolerant cultivars. Salt is a major abiotic factor affecting plant growth and secondary metabolism 1. Soil salinization has become a global problem with about 8 × 10 8 hectares of soil worldwide threatened by salinization 2. Salinity interferes with plant growth as it leads to physiological drought and ion toxicity 3. In addition, other secondary stresses, such as oxidative damage, can occur in plants subjected to high NaCl concentrations 1. With the increase of salinization, it is a tough challenge to increase grain output and achieve food security. Potato (Solanum tuberosum L.) is an extremely important food staple worldwide due to its versatility and nutritional value. However, potato is quite sensitive to salt stress, which is one of the most important factors limiting its cultivation 4 and which can lead to serious declines in yield 5,6. Therefore, there is a great need to improve the salt tolerance of potato and breed salt-tolerant varieties. What's more, illuminating the molecular mechanisms underlying salt tolerance and identifying the related genes of tolerant plants may contribute to further understanding the functions of these unique genes. Previous studies have revealed mechanisms underlying salt stress tolerance in plants. Plant membrane receptors sense extracellular salt stress stimuli, and then these stimuli signals are translated into intracellular signals through the generation of second messengers such as calcium, reactive oxygen species (ROS) and inositol phosphates. These second messengers then activate transcription factors (TFs) or protein kinases (PKs), inducing specific genes to be differentially expressed 7. These signal cascades result in the expression of multiple stress-responsive genes, the products of which can directly or indirectly confer s...

Potato plants that exhibited mosaic symptoms were collected in Xiangxi, Hunan province, China. Multiplex RT-PCR screening for common viruses revealed the presence of potato virus A (PVA) in these samples. ELISA with virus-specific antibodies confirmed infection by PVA in the plants. Rod-shaped virions of ~750 nm in length and ~13 nm in width were observed by transmission electron microscopy. One virus isolate (designated PVA-Hunan) was subjected to molecular characterization. The viral genome consisted of 9,567 nucleotides, excluding the poly(A) tail, and encoded a polyprotein of 3,059 amino acids. A second characteristic potyvirus open reading frame (ORF), pretty interesting Potyviridae ORF (pipo), was located at nucleotides 2,834-3,139. The isolate shared 84% to 98% and 93% to 99% sequence identity with other PVA isolates at the nucleotide and amino acid level, respectively. Phylogenetic analysis demonstrated that, within the PVA group, PVA-Hunan clustered most closely with the Finnish isolate Her, then with isolates 143, U, Ali, M and B11. The isolate TamMV stood alone at a separate branch. However, scanning of complete genome sequences using SimPlot revealed 99%-sequence identity between PVA-Hunan and TamMV in the 3'-proximal end of the genome (~nt 9,160 to the 3'end) and a 50%-94% (average~83%) identity upstream of nt 9,160. In contrast, 98% identity between PVA-Hunan and isolates M and B11 was detected for nucleotides 1 to ~9,160, but only ~94% for the 3'-proximal region, suggesting a genome recombination event (RE) at nt 9,133. The recombination breakpoint also was identified by the Recombination Detection Program (RDP). The RE was further confirmed by analysis of the CP gene, where the apparent RE was located.

Potato (Solanum tuberosum L.) is the fourth most important crop worldwide. Potato virus A (PVA) is one of the most harmful viruses infecting potatoes. However, the molecular mechanisms governing the responses to PVA infection in potato at the transcriptional and post-transcriptional levels are not well understood. In this study, we performed both mRNA and small RNA sequencing in potato leaves to identify the genes and miRNAs involved in the response to PVA infection. A total of 2,062 differentially expressed genes (DEGs) and 201 miRNAs (DEMs) were identified, respectively. Gene ontology (GO) and KEGG analysis revealed that these DEGs were involved in the transduction of pathogen signals, transcriptional reprogramming, induction of hormone signaling, activation of pathogenesis-related (PR) genes, and changes in secondary metabolism. Small RNA sequencing revealed 58 miRNA-mRNA interactions related to PVA infection. Some of the miRNAs (stu-miR482d-3p, stu-miR397-5p, etc) which target PR genes showed negative correlations between the DEMs and DEGs. Eight of the DEGs and three DEMs with their target genes were further validated by quantitative real time-PCR (qRT-PCR). Overall, this study provides a transcriptome-wide insight into the molecular basis of resistance to PVA infection in potato leaves and potenital candidate genes for improving resistance cultivars.