Name: Marlonni Maurastoni Araujo
Type: MSc dissertation
Publication date: 20/02/2018
Advisor:
Name |
Role |
|---|---|
| Jose Aires Ventura (M/D) | Co-advisor * |
| Patricia Machado Bueno Fernandes (M/D) | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Diolina Moura Silva | Internal Alternate * |
| Francisco Murilo Zerbini Junior | External Examiner * |
| Geraldo Rogério Faustini Cuzzuol | Internal Examiner * |
| Patricia Machado Bueno Fernandes (M/D) | Advisor * |
| Tathiana Correa Rangel | External Alternate * |
Summary: ABSTRACT
Brazil and the state of Espírito Santo are one of the largest producers and exporters of papaya (Carica papaya L.) in the world. However, the papaya sticky disease (PSD) has affected production and caused the destruction of serveral orchads in Brazil and Latin America. PSD is associated with a viral complex formed by papaya meleira virus (PMeV) and papaya meleira virus 2 (PMeV2). Both PMeV and PMeV2 are encapsidated by particles formed by PMeV. Asymptomatic plants are detected with the PMeV while the symptoms are visualized only after flowering and infection by the PMeV2. Spontaneous exudation fluid latex from fruits and necrosis at the edges of young leaves are PSD symptoms caused by a osmotic imbalance in laticifer cells. To date, electron microscopy studies have shown that viral particles are located in these cells. However, in this work, we present evidence suggesting other possible tissues of infection. In addition, no cellular communication by apoplast or simplast, well established for other plants containing laticifers, is documented in C. papaya. Thus, non-laticiferous tissue can be used by the viral complex for replication and movement. To prove this hypothesis, it was conducted the identification of PMeV and PMeV2 RNA in leaf tissues of plants with symptoms and without symptoms. Laticifer cell communication was identified by staining with aniline blue for visualization of plasmodesmata. The results show that the PMeV is also capable of infecting parenchyma cells, mainly cells between the xylem vessels and between the phloem bundles. Interestingly, between the colenchyma and the phloem bundles, it is possible to observe isolated and infected cells forming a infection cord. The staining with aniline blue did not show plasmodesma in laticifers of C. papaya.
Keywords: Papaya sticky disease PMeV complex laticifer in situ hybridization
