Characterising resistance to Turnip mosaic virus (TuMV) in Turnip (Brassica rapa rapa)

A Brassica rapa rapa L. line has been identified with high resistance to seven isolates of Turnip mosaic virus (TuMV) (including UK 1, CHN 5, CZE 1, CDN 1, GBR 6, POL 1 and UK 4) representing the major pathotypes of the virus. Resistant plants showed no symptoms following mechanical inoculation with TuMV and no virus was detected in the plants by ELISA. A cross was made between the rapid-cycling Brassica rapa line R-o-18 (which has been found to be susceptible to all the TuMV isolates) and a plant from the resistant B. rapa rapa line. The small amount of the F1 generation seed available from this cross has been grown and inoculated with the seven TuMV isolates. F1 plants were uniformly resistant to the UK 1 isolate of TuMV, uniformly susceptible to the CHN 5 isolate (only 2 plants inoculated) and segregated for resistance and susceptibility to the other five TuMV isolates. This suggested that the parent B. rapa rapa plant used in the cross was probably homozygous for one, or more dominant resistance genes to the UK 1 isolate of TuMV and heterozygous for one, or more dominant resistance genes to the other TuMV isolates. When self seed (S1) from the parent plant from the resistant line was inoculated with the TuMV isolates GBR 6 and UK 4, the segregation for the former isolate was not significantly different from 3 resistant to 1 susceptible, whereas for the latter isolate, the segregation was 4 resistant to 9 susceptible, suggesting resistance to GBR 6 is controlled by a single dominant gene, whereas resistance to UK 4 is controlled by two or more dominant resistance genes. The putative resistance genes appear to confer hitherto unknown dominant TuMV resistance specificities, and in combination have the exciting potential of providing durable resistance to TuMV

Characterization of a Syrian Chickpea chlorotic stunt virus strain and production of polyclonal antibodies for its detection

Reverse transcription-polymerase chain reaction analysis with two primer sets of luteoviruses was used to characterize an isolate of Chickpea chlorotic stunt virus (CpCSv, genus Polerovirus, family Luteoviridae) (SC402-08) collected from Lattakia, Syria, during the 2007‒2008 chickpea growing season. Sequence analysis revealed that the coat protein gene of the isolate shared nucleotide sequence identities ranging from 97 to 98% with the CpCSv isolates from Egypt, morocco and Syria. The capsid protein was separated as a protein of approximately 20 kDa in sodium dodecyl sulphate polyacrylamide gel electrophoresis, and was visually detected by its reaction with CpCSV monoclonal antibody in Western blot. SC402-08 isolate of CpCSV was purified from faba bean-infected plants, and yielded 112–182 μg of purified virions kg-1 of infected tissue. The purified preparation was injected into a white rabbit, and an antiserum was obtained and used to detect CpCSv in infected tissues by tissue-blot immunoassay. The antiserum obtained was able to detect CpCSv by the immunoassay up to a dilution of 1:1,024,000

Characterization of a Syrian <em>Chickpea chlorotic stunt virus</em> strain and production of polyclonal antibodies for its detection

Reverse transcription-polymerase chain reaction analysis with two primer sets of luteoviruses was used to characterize an isolate of <em>Chickpea chlorotic stunt virus</em> (CpCSv, genus <em>Polerovirus</em>, family <em>Luteoviridae</em>) (SC402-08) collected from Lattakia, Syria, during the 2007‒2008 chickpea growing season. Sequence analysis revealed that the coat protein gene of the isolate shared nucleotide sequence identities ranging from 97 to 98% with the CpCSv isolates from Egypt, morocco and Syria. The capsid protein was separated as a protein of approximately 20 kDa in sodium dodecyl sulphate polyacrylamide gel electrophoresis, and was visually detected by its reaction with CpCSV monoclonal antibody in Western blot. SC402-08 isolate of CpCSV was purified from faba bean-infected plants, and yielded 112–182 μg of purified virions kg-1 of infected tissue. The purified preparation was injected into a white rabbit, and an antiserum was obtained and used to detect CpCSv in infected tissues by tissue-blot immunoassay. The antiserum obtained was able to detect CpCSv by the immunoassay up to a dilution of 1:1,024,000