Biodiversity of Mite Vector of Pigeonpea sterility mosaic virus in Tamil Nadu, India

摘要

Sterility mosaic disease (SMD) is the most economically important disease of pigeonpea (Cajanus cajan L.) in the Indian subcontinent (Kumar et al., 2004). The SMD-affected plants show severe stunting and mosaic symptoms on leaves with complete or partial cessation of flowering (sterility). The disease is caused by the Pigeonpea sterility mosaic virus (PPSMV), transmitted by an eriophyid mite, Aceria cajani (Acari: Arthropod) (Kumar et al, 2003). PPSMV occurs as several geographically distinct pathotypes, which differ in their severity on pigeonpea genotypes (Reddy et al., 1993; Kumar et al., 2004). Based on differential host range studies, the isolate prevailing in Coimbatore region of Tamil Nadu was regarded as a distinct pathotype (referred as C isolate), which has an ability to overcome host resistance selected against the PPSMV Patanchera (P) isolate. Recently, PPSMV-C isolate was characterized and shown to have properties distinct from that of P isolate (Latha, 2003). In this study, the diversity in mite populations vectoring PPSMV-C was analyzed by assessing variability in nucleotide sequence of the ribosomal DNA (rDNA) internal transcribed spacers (ITS) and associated rDNA genes by restriction analysis and comparison of the profiles with the reference clones that contain inserts of rDNA ITS regions from Patancheru, Andhra Pradesh. This rDNA-based method was shown to be highly useful for assessing diversity in eriophyid species (Kumar et al, 1999).