Histopathology of leaf lesions caused by different plant viruses transmitted by Brevipalpus mites

• Grant number: 16/10799-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2016
• End date: July 31, 2017
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Elliot Watanabe Kitajima
• Grantee: Gustavo Mortean Filippi
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 14/08458-9 - Plant viruses transmitted by Brevipalpus mites (Acari: Tenuipalpidae) - BTV: survey, identification, molecular characterization, phylogeny; virus/vector/host relationhip; biology, taxonomy and management of the mite, AP.TEM

Abstract

Among plant viruses transmitted by the tenuipalpid mite Brevipalpus (BTV), Citrus leprosis virus C (CiLV-C) is by far the most important economically, having received more attention. In the last 20 years, significant progresses have been made on the knowledge of its nature (genome, interaction with the host and vector) as well as on epidemiology and management of the caused disease. In the Wake of these studies several other BTV were recognized in cultivated plants such as coffee, passion flower and many ornamentals. Besides CiLV-C some of them had their genome partially or entirely sequenced. There are at least two completely distinct virus groups being transmitted by Brevipalpus: cytoplasmic (BTV0C) and nuclear (BTV-N). BTV-C have short bacilliform particles and induce a vacuolated, electron dense viroplasm, and is represented by Citrus leprosis virus C, genus Cilevirus. BTV-N has rod-like particles and causes an electron lucent viroplasm in the nucleus. Orchid fleck virus (OFV) represents this group, to which is attributed the genus Dichorhavirus. To better understand the virus/host relationship a project is being proposed to study the histopathology of the leaf lesions caused by BTV (N and C) in different pathosystems to observe a possible pattern and find evidences which may explain the reasons that preclude the systemic infection of these viruses, as well as to observe phenomena occurring in the interface between healthy and infected cells, at the border of the lesions. There are only detailed studies carried out with CiLV-C and CiLV-N and some fragmentary observations made with few VTB. Initially it is proposed to study lesions caused by the viruses of green spot of passion fruit (PFGSV) and leprosis of Ligustrum (LigLV), both BTV-C, and coffee ringspot (CoRSV) and Clerodendrum chlorotic spot (ClCSV), both BTV-N. These investigations will be made using light and scanning electron microscopy. It is expected to obtain besides tissue alterations, informations regarding lesion evolution and distribution of the pathogen. The candidate for the scholarship is a student of Agricultura Sciences at ESALQ, in his 4th year with excellent grades with previous training in plant anatomy. The Project is simple and linear, suited for a Scientific Initiation level. He will be exposed to basic scientific reasoning ad methodologies. This Project is part of a thematic Project about BTV (Fapesp 2014/08458-9) coordinated by the responsible for the student.