Movement and distribution of tomato spotted wilt virus in resistant and susceptible accessions of Capsicum spp.

Resistant Capsicum chinense accessions PI-152225 and PI-159236 and the susc eptible cultivar 'Negral' of Capsicum annuum were used in three experiments to characterize the resistance to tomato spotted wilt virus (TSWV) in thes e materials. In the first experiment viral movement in the whole plant was studied at two growth stages (2- and 4-leaf stage). In the second experimen t the movement within the inoculated leaf was analysed at three growth stag es (2-, 3-, and 4-leaf stage). Two techniques were used in this assay: doub le antibody sandwich - enzyme-linked immunosorbent assay (DAS-ELISA) and di rect tissue blotting (DTB). In the latter experiment viral accumulation in different types of samples was evaluated by DAS-ELISA. The DTB technique sh owed that viral movement within the inoculated leaf is restricted in the re sistant plants. The inoculated area was not totally infected in resistant a ccessions and slower viral movement within the inoculated area was observed . Detection of weak ELISA positives in inoculated and adjacent areas in res istant plants might not be caused by a lower viral replication, but may res ult from a low foliar area affected by the virus, as viral movement was res tricted in certain areas around the necrotic lesions. However, ELISA absorb ance values of the necrotic lesions were similar to the values of infected tissue of 'Negral'. These observations point to a restricted viral cell-to- cell movement in the resistant accessions.