Proteome Mapping of South African Cassava Mosaic Virus-Infected Susceptible and Tolerant Landraces of Cassava.

Elelwani Ramulifho,Marie Emma Christine Rey

doi:10.3390/proteomes9040041

Abstract

The production of cassava is threatened by the geminivirus South African cassava mosaic virus (SACMV), which causes cassava mosaic disease. Cassava landrace TME3 shows tolerance to SACMV, while T200 is highly susceptible. This study aimed to identify the leaf proteome involved in anti-viral defence. Liquid chromatography mass spectrometry (LC-MS) identified 2682 (54 differentially expressed) and 2817 (206 differentially expressed) proteins in both landraces at systemic infection (32 days post infection) and symptom recovery (67 days post infection), respectively. Differences in the number of differentially expressed proteins (DEPs) between the two landraces were observed. Gene ontology analysis showed that defence-associated pathways such as the chloroplast, proteasome, and ribosome were overrepresented at 67 days post infection (dpi) in SACMV-tolerant TME3. At 67 dpi, a high percentage (56%) of over-expressed proteins were localized in the chloroplast in TME3 compared to T200 (31% under-expressed), proposing that chloroplast proteins play a role in tolerance in TME3. Ribosomal_L7Ae domain-containing protein (Manes.12G139100) was over-expressed uniquely in TME3 at 67 dpi and interacts with the ribosomal protein Sac52 (RPL10). RPL10 is a known key player in the NIK1-mediated effector triggered immunity (ETI) response to geminivirus infection, indicating a possible role for Sac52 in SACMV recovery in TME3. In conclusion, differential protein expression responses in TME3 and T200 may be key to unravel tolerance to CMD.

Highlights

Cassava (Manihot esculenta Crantz), a perennial shrub and root crop belonging to the Euphorbiaceae family, is the third most important food crop in tropical regions after rice and maize
With regard to the role that ribosomal protein L10 (RPL10) may play in TME3 tolerance to South African cassava mosaic virus (SACMV), we propose that this protein may be expressed in abundance and phosphorylated by membrane-bound NIK1, which would lead to downstream translational suppression of viral proteins and virus movement, which would contribute to the symptom and virus recovery phenotype observed in TME3 (Figure 1a)
We identified proteins in the ribosome, chloroplast, ubiquitination, and cytoplasm Gene ontology (GO), and we propose that these proteins and their connected networks are contributors to SACMV and symptom recovery in TME3

Summary

Introduction

Cassava (Manihot esculenta Crantz), a perennial shrub and root crop belonging to the Euphorbiaceae family, is the third most important food crop in tropical regions after rice and maize. It is grown in over 90 countries as it is a good source of carbohydrates and produces higher yields in adverse conditions compared to most other crops. According to Faostat (http://www.fao.org/faostat/, accessed on 11 August 2021), over 303 million tonnes of cassava were produced in 2019, with Africa being the major contributor (63.3% production share). Cassava does provide food and brings employment to the impoverished regions of Africa. There is no doubt that the cassava crop is of importance; its production is threatened by pests and pathogens, resulting in yield losses

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