Papaya Mosaic Virus (PapMV)

Papaya Mosaic Virus (PapMV)
Introduction
Life cycle
Symptoms
Management and Controls

1. Plant pathogenic virus Genus: Potex virus Family: Alphaflexiviridae Papaya Mosaic Virus (PapMV) BY: SURAJ SHRESTHA

2. It is a filamentous, flexuous rod, 530nm in length. Virus is monopartite strand of positive sense, single stranded RNA surrounded by a capsid made for single viral encoded protein. Genome is completely sequenced and 6656 nucleotides long.

3. Mode of transmission: By Mechanical Inoculation. No insect vector is involved and not transmitted in seeds. But Vimala et al.,2017 reported Aphid ( Aphis craccivora ) as vector.(sap transmissible).

4. Host restricted to: Cucurbits and Papaya.

5. Viral replication is cytoplasmic . Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription . Translation takes place by leaky scanning. The virus exits the host cell by tripartite non-tubule guided viral movement. Transmission routes are mechanical . Life Cycle of Virus

6. SYMPTOMS

7. Seriously affected when about a year old. First infection in top leaves. Mild mosaic symptoms on papaya leaves and stunting of plants. No symptoms in stem and flowers.

8. INFECTED HEALTHY

9. Approximately 5 days after inoculation, green house young seedlings show vein pairing and downward cupping of leaves while adopting upright position.

10. Destruction of affected plants. Use virus free seedlings. Disinfect working tools or heat them in an oven at 150 o C for 1 hour to kill the virus. Working tools or gloves can be dipped in 0.525% sodium hypochlorite & then rinsed in water. Do NOT save seed from infected crops. Crop rotation with non host crop. Soil sterilization. Management and Controls There are no cures for viral diseases such as mosaic once a plant is infected.

11. Thermotherapy + Cryotherapy

12. Chavez-Calvillo, Gabriela & Contreras-Paredes, Carlos & Mora, Javier & Noa- Carrazana , Juan Carlos & Serrano-Rubio, A. Alejandra & Dinkova , Tzvetanka & Carrillo-Tripp, Mauricio & Silva-Rosales, Laura. (2016). Antagonism or synergism between papaya ringspot virus and papaya mosaic virus in Carica papaya is determined by their order of infection. Virology. 489. 179-191. 10.1016/j.virol.2015.11.026.

13. PapMV PRSV (Chávez-Calvillo et al. 2016)

14. Their studies showed that: Two unrelated viruses, papaya ringspot virus (PRSV) and papaya mosaic virus (PapMV) produce different symptomatic outcomes during mixed infection depending on the inoculation order. Synergism occurs in plants infected first with PRSV or in plants infected simultaneously with PRSV and PapMV. And antagonism occurs in plants infected first with PapMV and later inoculated with PRSV .