Anatomical Deviations Caused by a Monopartite Geminivirus Infection in Tissues of Tomato Plants

Abstract

Tomato yellow leaf curl virus (TYLCV) causing major yield losses in tomato (Lycopersicon esculentum L.) crops was isolated in Kuwait. The virus was found to produce characteristic external symptoms of yellowing and curly leaves on tomato test plants. Electron Microscopy of ultra‐thin sections in infected leaves showed several anatomical deviations in the ultrastructure of some organelles such as chloroplasts associated with alteration and severe damage in thylakoids and grana that contain photosynthetic pigments of chlorophyll and carotenoids. Abnormal building up of oily inclusions and empty vacuoles in the chloroplast stromas were observed. Uneven thickenings in the cell walls of the phloem tissues were found in all samples showed the characteristic external symptoms compared with healthy plant tissues. The virus identity was confirmed using Polymerase Chain Reaction technology, Southern Blot Hybridization and Dot Blot analysis. It was revealed that the causal virus was characterized as a monopartite Geminivirus. It has been found that uneven thickening in the cell walls resulted in developing the curly symptoms in tomato leaves. It was also concluded from this study that in response to TYLCV infection, severe damage in chloroplasts including thylakoids in grana resulted in 44 ‐79% reduction in chlorophyll 'a and 'b causing the yellowing symptoms and crop losses.