All issues

Identification and Biological Characteristics of Cowpea Mild Mottle Virus in Taiwan
Severe symptoms caused by cowpea mild mottle virus (CpMMV) infecting (A) asparagus bean and (B) French bean were observed in the fi eld. By mechanical inoculation, leaf mottle on (C) asparagus bean and (D) French bean were developed.
Severe symptoms caused by cowpea mild mottle virus (CpMMV) infecting (A) asparagus bean and (B) French bean were observed in the fi eld. By mechanical inoculation, leaf mottle on (C) asparagus bean and (D) French bean were developed.

Author:Ying-Huey Cheng*, Chin-Chih Chen, Lan-Yi Chien, and Chin-An Chang

Abstract:

    Sample plants of asparagus bean and French bean bearing putatively viral symptoms were found in vegetable gardens in Chiayi and Nantou Counties, Taiwan. The symptomatic plants were mechanically inoculated to Chenopodium quinoa and two virus isolates, cowpea mild mottle virus (Cp-MMV)-V and CpMMV-P, were isolated after 3 times of single lesion isolation. The virus sources were established by inoculating local lesions to C. quinoa or Nicotiana benthamiana. By back-inoculation, plants of asparagus bean and French bean developed symptoms similar to those found in the field. When two isolates were inoculated on other legume crops, there was no obvious dwarfing or stunting in the whole plant, but some mild symptoms such as mottle and yellow spots can be seen on leaves. CpMMV has not been detected to be transmitted through seeds by growing out test. Total RNAs extracted from diseased asparagus bean and French bean used as templates, and reverse transcription-ploymerase chain reaction were performed with degenerate primers for potyviruses (Hrp5/Pot1). Unexpectedly, an 1 Kb of DNA product was amplified. Comparing with gene sequences on GenBank, sequences of this amplified DNA includes part of the 3’end of the coat protein gene of CpMMV. The complete coat protein gene was cloned with specific primers based on the reported sequences and then for sequence analysis. The coat protein gene of CpMMV-V (JX070669) and CpMMV-V (JX020701) shared 88.8% and 97.6% sequence identities of nucleotide and amino acid, respectively. Comparing with other coat protein genes of CpMMV, the nucleotide sequence identity is 98.7–75.7%, and the amino acid sequence identity is 97.9–91.3%. Electron micrographs showed that carlavirus-like particles were found in the leaf dips of infected asparagus bean and French bean samples. The coat protein obtained by partially purified viral particles and through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used for antiserum preparation. The antiserum was available for Western blot and enzyme-linked immunosorbent assay (ELISA), especially are suitable for field detection and investigation. Therefore, we found that CpMMV is commonly infected French bean in middle Taiwan. In addition to asparagus bean and French bean, whether CpMMV affects other leguminous crops needs more investigation.

Key words:Cowpea mild mottle virus (CpMMV), Coat protein, Antisera

Download:Download PDF PDF Links

  • Back
  • Top
  • Back
  • Top