| Several experiments were conducted in the glass house, net house and in the laboratory to check the transmission pathways and to identify the causal agent of leaf mosaic of jute. Seed to plant transmission was studied in aluminium tray and in cassette holders. Again seed to plant to seed transmission study was conducted in successive two seasons. In the second year seeds collected from the infected plants only were sown. In graft transmission study five grafting techniques (viz. peg, veneer, gooti, root grafting and T-budding) were employed. Vector transmission was studied under insect proof cage. Again, infected leaves were subjected to study under light microscope to observe the inclusion body. In molecular detection polymerase chain reaction (PCR) was employed using begomovirus specific primes in nucleic acid preparation from mosaic infected jute leaf to confirm the causal agent. It was observed that the cultivar D-154 showed the highest percentage of seed to plant transmission of the causal agent in both aluminium tray and cassette holders. In seed to plant to seed transmission it was observed that seeds obtained from the infected plants gave higher percentage of infected plants in the succeeding year than those obtained from healthy ones. In the graft transmission study it was noted that the causal agent was readily transmitted through all grafting techniques attempted. Graft transmission was more successful when hosts of same cultivar were used as both scion and stock. In the vector transmission study results obtained indicated that the causal agent was transmitted persistently by whitefly (Bemisia tabaci). The results showed that at least 3 and 1 whiteflies were required to transmit the causal agent when both AFP and IFP were 24hr and 48hr respectively. The minimum AFP and IFP were 30 minutes and 15 minutes respectively. The persistence of causal agent inside the vector was at best 10 days. Under light microscope large, blue-violet, prominent nuclear inclusion bodies were readily detected from infected leaf tissues which are indicative of geminivirus infection. This is probably the first study of this kind in mosaic infected jute leaf. In molecular detection the primers amplified 1.2 kb of the DNA fragment. The results obtained in present study conclude that the causal agent of leaf mosaic of jute is transmitted through seed, grafts and vector whitefly and microscopic and molecular study confirm that begomoviruses are responsible for the leaf mosaic in jute. |
