Occurrence of CBSD and associated Ugandan cassava brown streak virus in Mayotte Island

Cassava: major staple food for people in Comoros Islands and Madagascar in the Indian Ocean

Major biotic constraint: cassava mosaic disease (CMD) caused by a complex of cassava mosaic geminiviruses

(CMGs; De Bruyn et al., BMC Evol. Biol. 2012; Harimalala et al., Plant Pathol. 2014)

Expanding cassava brown streak disease epidemic in East Africa: Cassava brown streak virus (CBSV; Monger

et al., Arch. Virol. 2010) and Ugandan cassava brown streak virus (UCBSV; Winter et al., JGV 2010)

New symptoms of yellowing on leaves and brown necrotic roots: suspicion of cassava brown streak disease

(CBSD) caused by cassava brown streak ipomoviruses (CBSVs)

► First report of cassava brown streak disease in Mayotte

► Causal agent: Ugandan cassava brown streak virus (Ipomovirus, Potyviridae)

► Great significance for health managing of cassava in southwest Indian Ocean Islands

► Urgent need of virus-free certified material of farmer-prefered landraces

1.RT-PCR virus-specific detection

Michel Roux-Cuvelier1*, David Teyssedre1, Thomas Chesneau1,2, Charles Jeffray1, Delphine Massé3, Katia Jade1, Anli Liachourutu

Abdoul Karime4, Bruno Hostachy2, Bernard Reynaud1, James Legg5 and Jean-Michel Lett1

1CIRAD, UMR PVBMT, Ile de la Réunion, F-97410 Saint-Pierre, La Réunion, France, 2Lycée Agricole Professionnel de Coconi, BP 02, F-97670 Coconi, Mayotte, France, 3ANSES-LSV Réunion, Pôle de Protection des Plantes, F-97410 Saint-Pierre, La Réunion, France, 4DAAF Mayotte, Service de l’Alimentation – Santé des végétaux, BP 103, F-97600 Mamoudzou, Mayotte, France,

5International Institute of Tropical Agriculture, PO Box 34441, Dar es Salaam, Tanzania

► Mayotte isolates genetically more related to UCBSV

isolates than to CBSV isolates from East Africa, and

represent a separate lineage intermediate between current

isolates of CBSV and UCBSV

3. Phylogenetic reconstruction

▼ RT-PCR products of the expected size for UCBSV

2. Sequence similarity research

- Symptomatic leaf samples collected in March and June 2014

- Two-step RT-PCR using CBSDDF2 and CBSDDR primers (Mbanzibwa et al., JGV 2011)

- Simultaneous virus-specific detection of CBSV (344bp)

and UCBSV (440bp)

- RT-PCR products directly and bi-directionally sequenced

- Highest nucleotide identity research (BLASTn, NCBI)

Suspicion of CBSD in Mayotte ► identity of the causal agent(s)?

▼ Highest nucleotide identity (86%) with isolates of

UCBSV from Uganda and Malawi

- Sequences of 359 bp

- Maximum likelihood tree (MEGA6)

Conclusions

Positive controls: UCBSV (T+1; T+2); CBSV (T+6); Cassava samples (M1 to M19)

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