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

Abstract

Resistant Capsicum chinense accessions PI-152225 and PI-159236 and the susceptible cultivar ‘Negral’ of Capsicum annuum were used in three experiments to characterize the resistance to tomato spotted wilt virus (TSWV) in these 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 experiment the movement within the inoculated leaf was analysed at three growth stages (2-, 3-, and 4-leaf stage). Two techniques were used in this assay: double antibody sandwich – enzyme-linked immunosorbent assay (DAS–ELISA) and direct tissue blotting (DTB). In the latter experiment viral accumulation in different types of samples was evaluated by DAS–ELISA. The DTB technique showed that viral movement within the inoculated leaf is restricted in the resistant plants. The inoculated area was not totally infected in resistant accessions and slower viral movement within the inoculated area was observed. Detection of weak ELISA positives in inoculated and adjacent areas in resistant plants might not be caused by a lower viral replication, but may result from a low foliar area affected by the virus, as viral movement was restricted in certain areas around the necrotic lesions. However, ELISA absorbance 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.

Keywords:

• resistance mechanism
• direct tissue blotting
• hypersensitive response