Identification and Analysis of Potential Genes Regulated by an Alphasatellite (TYLCCNA) that Contribute to Host Resistance against Tomato Yellow Leaf Curl China Virus and Its Betasatellite (TYLCCNV/TYLCCNB) Infection in Nicotiana benthamiana.

Chaohu Luo,Yan Xie,Zhan Qi Wang,Xianan Liu,Liling Zhao,Xueping Zhou

doi:10.3390/v11050442

Abstract

Recently, begomovirus/betasatellite disease complexes were found to be associated with alphasatellites, and their presence modulated disease symptoms and/or viral DNA accumulation in infected plants. However, the biological functions of alphasatellites during begomovirus/betasatellite infections remain unclear. Tomato yellow leaf curl China virus (TYLCCNV) associated with a betasatellite (TYLCCNB) is a widespread monopartite begomovirus in China. In the Yunnan province of China, the TYLCCNV/TYLCCNB disease complex is found in association with an alphasatellite (TYLCCNA). In this study, in order to explain the mechanisms underlying TYLCCNV/TYLCCNB infection and reductions in viral DNA accumulation caused by TYLCCNA, we analyzed the transcriptome profiles of Nicotiana benthamiana seedlings challenged by TYLCCNV/TYLCCNB or TYLCCNV/TYLCCNB/TYLCCNA using RNA sequencing. In total, 2272 and 1207 differentially expressed genes (DEGs) were identified to respond to TYLCCNV/TYLCCNB and TYLCCNV/TYLCCNB/TYLCCNA infections, respectively. Compared with the DEGs in the TYLCCNV/TYLCCNB-infected N. benthamiana seedlings, the number of DEGs in plants co-infected with TYLCCNV/TYLCCNB + TYLCCNA was significantly reduced. Additionally, 36 DEGs were identified to be regulated by TYLCCNA, six of which were further analyzed using the virus-induced gene silencing (VIGS) approach. Silencing of these six TYLCCNA responsive DEGs caused more severe disease symptoms and higher viral DNA accumulation levels, suggesting that TYLCCNA responsive DEGs may attenuate TYLCCNV/TYLCCNB infection.

Highlights

Viruses in the family Geminiviridae are circular single-stranded DNA phytopathogens packaged in viral twin particles [1,2,3,4]
To investigate the effects of alphasatellite TYLCCNA on the symptoms of virus-infected plants, we examined the time course of symptom development of N. benthamiana plants infected by Tomato yellow leaf curl China virus (TYLCCNV)
Consistent with our previous report that N. benthamiana seedlings showed no symptoms when agroinoculated with TYLCCNV alone [17], the virus genomic DNA was detected by PCR in all 20 seedlings agroinoculated with TYLCCNV at 7 dpi (Figure 1A and Table 1)

Summary

Introduction

Viruses in the family Geminiviridae are circular single-stranded DNA phytopathogens packaged in viral twin particles [1,2,3,4]. They are currently divided into nine genera: Begomovirus, Mastrevirus, Topocuvirus, Curtovirus, Becurtovirus, Turncurtovirus, Eragrovirus, Grablovirus and Capulavirus by the International Committee on Taxonomy of Viruses [5]. Begomoviruses are classified as New World (the Americas) or Old World (Europe, Africa, Asia and Australasia) based on their geographic origins [6]. The genomes of begomoviruses in the New World are bipartite, whereas the Old World begomoviruses have either a monopartite or bipartite genome [13]

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Conclusion