Transcriptional response of virus-infected cassava and identification of putative sources of resistance for cassava brown streak disease

M N Maruthi; Sophie Bouvaine; Hale A Tufan; Ibrahim U Mohammed; Rory J Hillocks

doi:10.1371/journal.pone.0096642

Transcriptional response of virus-infected cassava and identification of putative sources of resistance for cassava brown streak disease

PLoS One. 2014 May 20;9(5):e96642. doi: 10.1371/journal.pone.0096642. eCollection 2014.

Authors

M N Maruthi¹, Sophie Bouvaine¹, Hale A Tufan¹, Ibrahim U Mohammed¹, Rory J Hillocks¹

Affiliation

¹ Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, United Kingdom.

Abstract

Cassava (Manihot esculenta) is a major food staple in sub-Saharan Africa, which is severely affected by cassava brown streak disease (CBSD). The aim of this study was to identify resistance for CBSD as well as to understand the mechanism of putative resistance for providing effective control for the disease. Three cassava varieties; Kaleso, Kiroba and Albert were inoculated with cassava brown streak viruses by grafting and also using the natural insect vector the whitefly, Bemisia tabaci. Kaleso expressed mild or no disease symptoms and supported low concentrations of viruses, which is a characteristic of resistant plants. In comparison, Kiroba expressed severe leaf but milder root symptoms, while Albert was susceptible with severe symptoms both on leaves and roots. Real-time PCR was used to estimate virus concentrations in cassava varieties. Virus quantities were higher in Kiroba and Albert compared to Kaleso. The Illumina RNA-sequencing was used to further understand the genetic basis of resistance. More than 700 genes were uniquely overexpressed in Kaleso in response to virus infection compared to Albert. Surprisingly, none of them were similar to known resistant gene orthologs. Some of the overexpressed genes, however, belonged to the hormone signalling pathways and secondary metabolites, both of which are linked to plant resistance. These genes should be further characterised before confirming their role in resistance to CBSD.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Disease Resistance / genetics*
Manihot / genetics*
Manihot / virology*
Plant Diseases / genetics*
Plant Diseases / virology*
Potyviridae / genetics*
Potyviridae / metabolism

Grants and funding

The authors acknowledge the funding received for part of this work from the African Union Commission through the grant: AURG/2/141/2012. Some of the costs were covered internally by the University of Greenwich by employing HAT for carrying out this work (grant ID E0198). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.