Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.

Rice yellow mottle virus (RYMV) is a major pathogen of rice in Africa. RYMV has a narrow host range limited to rice and a few related poaceae species. We explore the links between the spread of RYMV in East Africa and rice history since the second half of the 19th century. The phylogeography of RYMV...

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Main Authors: Innocent Ndikumana, Geoffrey Onaga, Agnès Pinel-Galzi, Pauline Rocu, Judith Hubert, Hassan Karakacha Wéré, Antony Adego, Mariam Nyongesa Wéré, Nils Poulicard, Maxime Hebrard, Simon Dellicour, Philippe Lemey, Erik Gilbert, Marie-José Dugué, François Chevenet, Paul Bastide, Stéphane Guindon, Denis Fargette, Eugénie Hébrard
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-06-01
Series:PLoS Pathogens
Online Access:https://doi.org/10.1371/journal.ppat.1013168
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author Innocent Ndikumana
Geoffrey Onaga
Agnès Pinel-Galzi
Pauline Rocu
Judith Hubert
Hassan Karakacha Wéré
Antony Adego
Mariam Nyongesa Wéré
Nils Poulicard
Maxime Hebrard
Simon Dellicour
Philippe Lemey
Erik Gilbert
Marie-José Dugué
François Chevenet
Paul Bastide
Stéphane Guindon
Denis Fargette
Eugénie Hébrard
author_facet Innocent Ndikumana
Geoffrey Onaga
Agnès Pinel-Galzi
Pauline Rocu
Judith Hubert
Hassan Karakacha Wéré
Antony Adego
Mariam Nyongesa Wéré
Nils Poulicard
Maxime Hebrard
Simon Dellicour
Philippe Lemey
Erik Gilbert
Marie-José Dugué
François Chevenet
Paul Bastide
Stéphane Guindon
Denis Fargette
Eugénie Hébrard
author_sort Innocent Ndikumana
collection DOAJ
description Rice yellow mottle virus (RYMV) is a major pathogen of rice in Africa. RYMV has a narrow host range limited to rice and a few related poaceae species. We explore the links between the spread of RYMV in East Africa and rice history since the second half of the 19th century. The phylogeography of RYMV in East Africa was reconstructed from coat protein gene sequences (ORF4) of 335 isolates sampled over two million square kilometers between 1966 and 2020. Dispersal patterns obtained from ORF2a and ORF2b, and full-length sequences converged to the same scenario. The following imprints of rice cultivation on RYMV epidemiology were unveiled. RYMV emerged in the middle of the 19th century in the Eastern Arc Mountains where slash-and-burn rice cultivation was practiced. Several spillovers from wild hosts to cultivated rice occurred. RYMV was then rapidly introduced into the nearby large rice growing Kilombero valley and Morogoro region. Harvested seeds are contaminated by debris of virus infected plants that subsist after threshing and winnowing. Long-distance dispersal of RYMV is consistent (i) with rice introduction along the caravan routes from the Indian Ocean Coast to Lake Victoria in the second half of the 19th century, (ii) seed movement from East Africa to West Africa at the end of the 19th century, from Lake Victoria to the north of Ethiopia in the second half of the 20th century and to Madagascar at the end of the 20th century, (iii) and, unexpectedly, with rice transport at the end of the First World War as a troop staple food from the Kilombero valley towards the South of Lake Malawi. Overall, RYMV dispersal was associated to a broad range of human activities, some unsuspected. Consequently, RYMV has a wide dispersal capacity. Its dispersal metrics estimated from phylogeographic reconstructions are similar to those of highly mobile zoonotic viruses.
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institution Kabale University
issn 1553-7366
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language English
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publisher Public Library of Science (PLoS)
record_format Article
series PLoS Pathogens
spelling doaj-art-7b6f1c0bdb6e4931a09825eb4a1121ca2025-08-20T03:47:21ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742025-06-01216e101316810.1371/journal.ppat.1013168Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.Innocent NdikumanaGeoffrey OnagaAgnès Pinel-GalziPauline RocuJudith HubertHassan Karakacha WéréAntony AdegoMariam Nyongesa WéréNils PoulicardMaxime HebrardSimon DellicourPhilippe LemeyErik GilbertMarie-José DuguéFrançois ChevenetPaul BastideStéphane GuindonDenis FargetteEugénie HébrardRice yellow mottle virus (RYMV) is a major pathogen of rice in Africa. RYMV has a narrow host range limited to rice and a few related poaceae species. We explore the links between the spread of RYMV in East Africa and rice history since the second half of the 19th century. The phylogeography of RYMV in East Africa was reconstructed from coat protein gene sequences (ORF4) of 335 isolates sampled over two million square kilometers between 1966 and 2020. Dispersal patterns obtained from ORF2a and ORF2b, and full-length sequences converged to the same scenario. The following imprints of rice cultivation on RYMV epidemiology were unveiled. RYMV emerged in the middle of the 19th century in the Eastern Arc Mountains where slash-and-burn rice cultivation was practiced. Several spillovers from wild hosts to cultivated rice occurred. RYMV was then rapidly introduced into the nearby large rice growing Kilombero valley and Morogoro region. Harvested seeds are contaminated by debris of virus infected plants that subsist after threshing and winnowing. Long-distance dispersal of RYMV is consistent (i) with rice introduction along the caravan routes from the Indian Ocean Coast to Lake Victoria in the second half of the 19th century, (ii) seed movement from East Africa to West Africa at the end of the 19th century, from Lake Victoria to the north of Ethiopia in the second half of the 20th century and to Madagascar at the end of the 20th century, (iii) and, unexpectedly, with rice transport at the end of the First World War as a troop staple food from the Kilombero valley towards the South of Lake Malawi. Overall, RYMV dispersal was associated to a broad range of human activities, some unsuspected. Consequently, RYMV has a wide dispersal capacity. Its dispersal metrics estimated from phylogeographic reconstructions are similar to those of highly mobile zoonotic viruses.https://doi.org/10.1371/journal.ppat.1013168
spellingShingle Innocent Ndikumana
Geoffrey Onaga
Agnès Pinel-Galzi
Pauline Rocu
Judith Hubert
Hassan Karakacha Wéré
Antony Adego
Mariam Nyongesa Wéré
Nils Poulicard
Maxime Hebrard
Simon Dellicour
Philippe Lemey
Erik Gilbert
Marie-José Dugué
François Chevenet
Paul Bastide
Stéphane Guindon
Denis Fargette
Eugénie Hébrard
Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
PLoS Pathogens
title Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
title_full Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
title_fullStr Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
title_full_unstemmed Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
title_short Grains, trade and war in the multimodal transmission of Rice yellow mottle virus: An historical and phylogeographical retrospective.
title_sort grains trade and war in the multimodal transmission of rice yellow mottle virus an historical and phylogeographical retrospective
url https://doi.org/10.1371/journal.ppat.1013168
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