Why mosaic? Gene expression profiling of African cassava mosaic virus‐infected cassava reveals the effect of chlorophyll degradation on symptom development

Abstract

Cassava mosaic disease, caused by cassava begomoviruses, is the most serious disease for cassava in Africa. However, the pathogenesis of this disease is poorly understood. We employed high throughput digital gene expression profiling based on the Illumina Solexa sequencing technology to investigate the global transcriptional response of cassava to African cassava mosaic virus infection. We found that 3,210 genes were differentially expressed in virus-infected cassava leaves. Gene ontology term and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that genes implicated in photosynthesis were most affected, consistent with the chlorotic symptoms observed in infected leaves. The upregulation of chlorophyll degradation genes, including the genes encoding chlorophyllase, pheophytinase, and pheophorbide a oxygenase, and downregulation of genes encoding the major apoproteins in light-harvesting complex II were confirmed by qRT-PCR. These findings, together with the reduction of chlorophyll b content and fewer grana stacks in the infected leaf cells, reveal that the degradation of chlorophyll plays an important role in African cassava mosaic virus symptom development. This study will provide a road map for future investigations into viral pathogenesis.

Identification and regulation of host genes related to Rice stripe virus symptom production

“…Several studies have reported the down‐regulation of chloroplast‐related genes (ChRGs) or photosynthesis in plants infected with viruses, and this is presumed to be responsible for chlorosis. In African cassava mosaic virus (ACMV; genus Begomovirus )‐infected cassava, genes implicated in photosynthesis were mostly down‐regulated, including genes encoding the major apoproteins in light‐harvesting complex II (Liu et al ., ). In Sunflower chlorotic mottle virus (SuCMoV; genus Potyvirus )‐infected sunflower leaves, ChRGs, including psbA , rbcS , Cu/Zn sod , Fe sod , phosphoglycolate phosphatase , psbO , psaH and fnr , were down‐regulated, indicating progressive changes in determinants of redox homeostasis associated with chlorotic symptom development (Rodriguez et al ., ).…”

Suppression of nbe‐miR166h‐p5 attenuates leaf yellowing symptoms of potato virus X on Nicotiana benthamiana and reduces virus accumulation

“…Abnormal chloroplast and chloroplast‐related components are associated with viral symptoms. It has been well reported that the expression of genes implicated in photosynthesis and the components participating in photosynthesis is reduced in different virus‐infected plants (Baumgartnerova et al ., ; Funayama et al ., ; Lehto et al ., ; Liu et al ., ; Lu et al ., ; Rodriguez et al ., ). In a previous report, we have provided evidence that the down‐regulation of chloroplast‐related genes (ChRGs) contributes to RSV‐induced chlorosis or yellowing (Shi et al ., ).…”

Assessment of Banana Streak MY virus-based infectious clone vectors in Musa ssp.

“…(Fraile and García-Arenal, 2010;Lecoq et al, 1979;Lecoq et al, 2004;Liu et al, 2014;Palukaitis et al, 2013). (Jones, 2000) 20 …”

“…Such an interaction has been found to favour the virus as a source of inoculum or reservoir for primary viral acquisition by insect vectors (Biswas et al, 2012). Symptom fluctuations from severe to mild is also a common observation (Liu et al, 2014).…”

“…The first trait that is usually used to assess plant susceptibility is the visual qualitative symptom expression (Doumayrou et al, 2013). Induction of chlorotic symptoms in infected plants is contributed by an accumulation of viral proteins inside the chloroplasts to such levels that comprises the normal functioning of the plant manifested as symptoms (Bengyella et al, 2015;Liu et al, 2014). The virus overcomes all suppressors fronted by the plant as well as any preformed anti-pathogen compounds (Zhang et al, 2013).…”