Characterization by Next Generation Sequencing Reveals the Molecular Mechanisms Driving the Faster Evolutionary rate of Cassava brown streak virus Compared with Ugandan cassava brown streak virus

Titus Alicai; Joseph Ndunguru; Peter Sseruwagi; Fred Tairo; Geoffrey Okao-Okuja; Resty Nanvubya; Lilliane Kiiza; Laura Kubatko; Monica A Kehoe; Laura M Boykin

doi:10.1101/053546

bioRxiv · 10.1101/053546

Characterization by Next Generation Sequencing Reveals the Molecular Mechanisms Driving the Faster Evolutionary rate of Cassava brown streak virus Compared with Ugandan cassava brown streak virus

Titus Alicai·Joseph Ndunguru·Peter Sseruwagi·Fred Tairo·Geoffrey Okao-Okuja·Resty Nanvubya·Lilliane Kiiza·Laura Kubatko·Monica A Kehoe·Laura M Boykin

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Abstract

Cassava is a major staple food for about 800 million people in the tropics and subGtropical regions of the world. Production of cassava is significantly hampered by cassava brown streak disease (CBSD), which is caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). The disease is suppressing cassava yields in eastern Africa at an alarming rate. Previous studies have documented that CBSV is more devastating than UCBSV because it more readily infects both susceptible and tolerant cassava cultivars, resulting in greater yield losses. Using whole genome sequences from NGS data, we produced the first coalescentGbased species tree estimate for CBSV and UCBSV. This species framework led to the finding that CBSV has a faster rate of evolution when compared with UCBSV. Furthermore, we have discovered that in CBSV, nonsynonymous substitutions are more predominant than synonymous substitution and occur across the entire genome. All comparative analyses between CBSV and UCBSV presented here suggest that CBSV may be outsmarting the cassava immune system, thus making it more devastating and harder to control.

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Titus Alicai, Joseph Ndunguru, Peter Sseruwagi, Fred Tairo, Geoffrey Okao-Okuja, Resty Nanvubya, Lilliane Kiiza, Laura Kubatko, Monica A Kehoe, Laura M Boykin. 2016-05-16. Characterization by Next Generation Sequencing Reveals the Molecular Mechanisms Driving the Faster Evolutionary rate of Cassava brown streak virus Compared with Ugandan cassava brown streak virus. https://doi.org/10.1101/053546

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