Leaf anatomical aspects of CABMV infection in Passiflora spp. by light and fluorescence microscopy

Abstract

Cowpea aphid-borne mosaic virus (CABMV) is the main pathogen that affects passion fruit, causing woodiness disease in Brazil. The identification of sources of resistance in Passiflora is necessary for the development of resistant cultivars. The objective of this work was to evaluate the reaction of eight species of Passiflora to CABMV and to verify leaf anatomical changes caused by CABMV. Inoculations were performed and symptoms were evaluated until 55 days after inoculation using a scale ranging from 1 (without symptoms) to 4 (highly susceptible). Simultaneously, leaves from infected and control plants for anatomical analysis were collected. The severity of the disease was calculated using the disease index (DI%) and the means were grouped using the Scott-Knott test. The wild species Passiflora malacophylla, P. setacea and P. suberosa were classified as resistant to CABMV. In contrast, P. alata and P. edulis were susceptible to the virus, with DI values of 58.2 and 51.9%, respectively. Leaf anatomical changes were more drastic in P. edulis and P. alata. In P. edulis, the infection resulted in changes in the organization of the vascular bundles. Resistant wild species showed few anatomical changes. The resistance found in wild species opens the prospect of performing interspecific crosses.