| Virus infection threatens the yield and quality of lily resulting in great economic losses. Nowadays, it has been a serious problem in the production of lilies. In this research, we cloned the sequences of LSV and LMoV genomes and analyzed various characteristics using softwares and tools of bioinformatics. Also the physiological effects of CMV and LMoV infection were investigated. These would contribute to study on virual molecular characteristics, pathogenicity and molecular breeding of obtaining virus resistant plants.The Lilium Oriental hybrid'Casablanca'was used in this study. Total RNA was extracted to confirm the occurrence of LSV. A total of 13 recombinant plasmids were identified and sequenced that contained overlapping cDNA fragments of the LSV genome. The complete genome of Dalian isolate of LSV contained 8,394 nucleotides and six open reading frames (ORFs). The genome sequence of LSV-DL is analyzed with other four LSVs from different regions. According to the homology comparison and phylogenetic tree analysis, LSV-DL had a closer relationship with viruses isolated from India and Netherlands in the whole genome level, and shared high nucleotide sequence homology with the four others.The RNA of RdRp of LSV isolated from'Casablanca'was 5847nts in length, coding for a protein of 1,948 aa that we referred to as RdRp-DL. The gene of RNA-dependent RNA polymerase (RdRp) shared high nucleotide and amino acid sequence homology with other previously known isolates. Phylogenetic analysis indicated that this RdRp from LSV was close to the RdRps from PLV and KLV of the genus Carlavirus. Resluts from hydrophobic property demonstrated that the C-terminal was hydrophobic but the N-terminal was hydrophilic. The frequency of coils was 3 in the structure of RdRp. Conserved domain analysis indicated that there were four conserved domain:Typoviral methyltransferase, RNA dependent RNA polymerase, P-loop containing Nucleoside Triphosphaste Hydrolases and Carlavirus endopeptidase. Four tertiary structure models for the conserved domains were predicted by I-TASSER.The linear, single-strand positive sense RNA genome of LMoV from Lilium longiforum 'White Heaven'was 9,648 nucleotides in length (excluding the polyA tail) and contained a single large predicted ORF. The predicted translation product of this ORF contains 3,096 amino acids (aa) with a calculated Mr of 351.0 kDa (polyprotein). LMoV is a species of a bigger branch of the genus Potyvirus. Phylogenetic analysis indicated that LMoV was close to PVV, BYMV and CIYVV of the genus Potyvirus.We investigated the physiological and biochemical effects of LMoV and CMV infection of lily. Compared with control plants, both CMV and LMoV infected plants had lower chlorophyll content with the development of symptom, indicating that virus infection causes great damage on the photosynthesizer. The activities of SOD were enhanced in CMV and LMoV infected plants compared with control, rising 17.8%and 9.7%, respectively. The POD activities of CMV and LMoV infected plants were kept rising compared with control plants, especially that of the CMV infected plants, which was higher than control and increased most quickly after inoculation, rising 23.4%. The ratio of the activities of PPO between CMV /LMoV and control plants were 1.279 and 1.322. The activities of PPO declined both in infected and control plants, in which plants first rose, then immediately decreased, and changed more acutely than at the early stage. The activities of PAL were higher in infected plants than control plants, rising 23.0%and 14.8%, indicating that metabolic system was in disorder after virus infection and the secondary metabolism was activated. |
PDF Full Text Request