1Department of Plant Pathology, Tamil Nadu Agricultural University (TNAU), Coimbatore-641003, Tamil Nadu.
2International Crops Research Institute for Semi Arid Tropics (ICRISAT), Patancheru-502324.
Abstracts of Research Papers Presented during the National Symposium of Indian Virological Society at Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110 012, October 14–1.
Sterility mosaic disease (SMD) of pigeonpea is caused by the Pigeonpea sterility mosaic virus (PPSMV), transmitted by the eriophyid mite, Aceria cajani Channabasavanna (Acari: Arthropoda). Various geographic isolates of PPSMV ocur in India. The PPSMV isolate prevailing in the Tamil Nadu state (referred as Coimbatore (C) isolate) is physiologically aggressive and able to overcome resistance offered by several SMD-resistant pigeonpea genotypes. The C isolate has distinct reaction on pigeonpea host differentials and lacks the 32-kDa nucleoprotein detected with PPSMV isolates characterized from Patancheru (P) and Bangalore (B), India. Biological properties of the C isolate are similar to that of P and B isolates. Bio-diversity among the vector populations ws assayed by analyzing A. cajani collected from SMD-affected pigeonpea from Coimbatore and Vamban. PCR was used to amplify rDNA with A. cajani specific oligonucleotide primers, and they were analyzed by RFLP. The RFLP profiles of mite populations vectoring C isolate, and otehr PPSMV isolates in peninsular India are identical. Mites acquired virus in 10 min acquisition access feeding period, and inoculated in 60 min inoculatio feeding period, which is similar to virus transmission feeding periods of other isolates. This suggests that mites vectoring C isolate are A. cajani and that they transmit PPSMV with similar efficiency, confirming that the differences in biochemical properteis of PPSMV isolate is responsible for host resistance breakdown.
