Expression, purification and characterization of the Lily symptomless virus coat protein from Lanzhou Isolate

Background: Lily symptomless virus (LSV) is widespread in many countries where lily are grown or planted, and causes severe economic losses in terms of quantity and quality of flower and bulb production. To study the structure-function relationship of coat protein (CP) of LSV, to investigate antigenic relationships between coat protein subunits or intact virons, and to prepare specific antibodies against LSV, substantial amounts of CP protein are needed. Results: Thus, full-length cDNA of LSV coat protein was synthesized and amplified by RT-PCR from RNA isolated from LSV Lanzhou isolate. The extended 33.6 kDa CP was cloned and expressed prokaryoticly and then purified by Ni-ion affinity chromatography. Its identity and antigenicity of recombinant CP were identified on Western-blotting by using the prepared anti-LSV antibodies. Conclusions: The results indicate that fusion CP maintains its native antigenicity and specificity, providing a good source of antigen in preparation of LSV related antibodies. Detailed structural analysis of a pure recombinant CP should allow a better understanding of its role in cell attachment and LSV tropism. This investigation to LSV should provide some specific antibodies and aid to development a detection system for LSV diagnostics and epidemiologic surveys

Colour break in reverse bicolour daffodils is associated with the presence of Narcissus mosaic virus

<p>Abstract</p> <p>Background</p> <p>Daffodils (<it>Narcissus pseudonarcissus</it>) are one of the world's most popular ornamentals. They also provide a scientific model for studying the carotenoid pigments responsible for their yellow and orange flower colours. In reverse bicolour daffodils, the yellow flower trumpet fades to white with age. The flowers of this type of daffodil are particularly prone to colour break whereby, upon opening, the yellow colour of the perianth is observed to be 'broken' into patches of white. This colour break symptom is characteristic of potyviral infections in other ornamentals such as tulips whose colour break is due to alterations in the presence of anthocyanins. However, reverse bicolour flowers displaying colour break show no other virus-like symptoms such as leaf mottling or plant stunting, leading some to argue that the carotenoid-based colour breaking in reverse bicolour flowers may not be caused by virus infection.</p> <p>Results</p> <p>Although potyviruses have been reported to cause colour break in other flower species, enzyme-linked-immunoassays with an antibody specific to the potyviral family showed that potyviruses were not responsible for the occurrence of colour break in reverse bicolour daffodils. Colour break in this type of daffodil was clearly associated with the presence of large quantities of rod-shaped viral particles of lengths 502-580 nm in tepals. Sap from flowers displaying colour break caused red necrotic lesions on <it>Gomphrena globosa</it>, suggesting the presence of potexvirus. Red necrotic lesions were not observed in this indicator plant when sap from reverse bicolour flowers not showing colour break was used. The reverse transcriptase polymerase reactions using degenerate primers to carla-, potex- and poty-viruses linked viral RNA with colour break and sequencing of the amplified products indicated that the potexvirus <it>Narcissisus mosaic virus </it>was the predominant virus associated with the occurrence of the colour break.</p> <p>Conclusions</p> <p>High viral counts were associated with the reverse bicolour daffodil flowers that were displaying colour break but otherwise showed no other symptoms of infection. <it>Narcissus mosaic virus </it>was the virus that was clearly linked to the carotenoid-based colour break.</p

Variability in the coat protein of Lily symptomless virus isolates infecting various lily species.

The coat protein sequences were characterized of Lily symptomless virus (LSV) isolates infecting Lilium longiflorum, Lilium tigrinum, Hymenocalis littoralis (spider lily) and Asiatic and Oriental hybrid lilies in India. The Indian isolates showed 78-96% homology with each other. With LSV isolates from elsewhere in the world, the Indian isolates showed 83-98% homology. The LSV-L (L. longiflorum) and LSV-A (Asiatic hybrid) isolates had unique stretches in the middle portion of the protein not found in other LSV isolates, even the Indian ones. The LSV gene sequence from the spider lily isolate (LSV-S) was reported for the first time outside the Liliaceae. LSV-S was 84-96% similar to the other Indian isolates at the protein level. The isolate infecting tiger lily (LSV-T) was found to be different from the characterized isolates from elsewhere in the world (78-84% homology at the protein level). At the same time, LSV-T showed much variability in the C-terminal of the protein. A stretch of 41 amino acids in the C-terminal was unique to this isolate. LSV-T is proposed as a distinct isolate of LSV infecting L. tigrinum indigenous to India