First report of Tobacco ringspot virus occurring in Gladiolus in India

Gladiolus (Gladiolus grandiflorous) is cultivated for its cut flowers in many countries worldwide, including India, where plants are commonly infected with Bean yellow mosaic (BYMV) and/or Cucumber mosaic viruses (CMV). Also reported in gladiolus in different parts of the world, but limited in distribution, are Tobacco ringspot virus (TobRSV), Tomato ringspot virus (TomRSV), Tomato black ring virus (TBRV), Arabis mosaic virus (ArMV), Strawberry latent ringspot virus (SLRV), Tobacco rattle virus (TRV) and Tomato spotted wilt virus (TSWV) (Stein, 1995).

During a survey for viruses infecting gladiolus in Palampur, some plants of 22 cultivars hadflower colour-break symptoms, whereas others were symptomless. When indexed by ELISA using specific antibodies to BYMV (obtained from Sanofi, France) (Katoch et al., 2002), these plants were shown to be infected with of BYMV. However, symptomless plants of Gladiolus cv. Yellow Supreme, when indexed by DAS-ELISA using antibodies to TobRSV (obtained from Agdia, U.S.A.), were shown to be infected with TobRSV.

Sap from these symptomless TobRSV-infected gladioli induced necrotic local lesions 7-10 days after inoculation followed by systemic leaf malformation characteristic of TobRSV (Brunt et al., 1996) in mechanically-inoculated Nicotiana clevelandii and Vigna unguiculata seedlings. The presence of TobRSV.in these plants was confirmed by DAS-ELISA.

This is the first report of TobRSV occurring in Gladiolus in India. TobRSV can be transmitted on contaminated tools used during harvesting of flowers and corms, by its nematode vectors and in gladiolus seeds. To control the virus, therefore, we recommend the use of disease free planting material, good sanitation practices and vector management.