Biological features and in planta transcriptomic analyses of a Microviridae phage (CLasMV1) in “Candidatus Liberibacter asiaticus”

Authors: WANG, CHENG - South China Agricultural Univerisity; FANG, FANG - South China Agricultural Univerisity; LI, YUN - South China Agricultural Univerisity; ZHANG, LING - South China Agricultural Univerisity; WU, JINGHUA - South China Agricultural Univerisity; LI, TAO - South China Agricultural Univerisity; ZHENG, YONGQUIN - South China Agricultural Univerisity; XU, Q - South China Agricultural University; FAN, S - South China Agricultural University; Chen, Jianchi; DENG, XIAOLING - South China Agricultural Univerisity; ZHENG, ZHENG - South China Agricultural Univerisity

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2022
Publication Date: 9/2/2022
Citation: Wang, C., Fang, F., Li, Y., Zhang, L., Wu, J., Li, T., Zheng, Y., Xu, Q., Fan, S., Chen, J., Deng, X., Zheng, Z. 2022. Biological features and in planta transcriptomic analyses of a Microviridae phage (CLasMV1) in “Candidatus Liberibacter asiaticus”. International Journal of Molecular Sciences. 23(17). Article 10024. https://doi.org/10.3390/ijms231710024.
DOI: https://doi.org/10.3390/ijms231710024

Interpretive Summary: Citrus Huanglongbing (HLB, also called citrus greening disease) is a highly destructive disease threatening citrus production worldwide. HLB is caused by the infection of an unculturable bacterial pathogen called “Candidatus Liberibacter asiaticus”. Recently, a virus, called CLasMV1, infecting the HLB pathogen was identified, raising the interest of using the bacterial virus for HLB control. However, little is known about the CLasMV1 biology. In this study, multiple experiments were performed to evaluate the population variations and gene expressions of the virus under different environmental conditions. There was evidence that CLasMV1 could lyse and kill the HLB pathogen in citrus fruit pith tissue where the HLB pathogen was in high concentration. The new information will benefit future research in the HLB pathogen virus and HLB control.

Technical Abstract: “Candidatus Liberibacter asiaticus” (CLas) is the causal agent of citrus Huanglongbing (HLB) in China. A Microviridae phage, CLasMV1, was recently identified in CLas strains through metagenomic analyses. However, the biology of CLasMV1 phage remains to be studied. In this study, we analyzed the population dynamics of CLasMV1 between Dodder (Cuscuta campestris) and Asian citrus psyllid (ACP, Diaphorina citri Kuwayama), both acquired CLasMV1-infected CLas from an HLB citrus. All CLas-positive dodder samples were CLasMV1 positive, whereas only 32% of CLas-positive ACP samples were CLasMV1 positive. Quantitative analyses revealed a similar distribution pattern of CLasMV1 phage and CLas in six different tissue types among eight citrus cultivars. In all cultivars, fruit tissue samples had higher CLas abundance than leaf tissue samples. Transcriptome analyses provided the evidence for the possible lytic activity of CLasMV1 in CLas-infected fruit pith tissue as evidenced by high-level expressions of CLasMV1 genes, and CLas genes related to cell wall biogenesis and remodeling to maintain the CLas cell envelope integrity. The upregulation of CLas genes involved in restriction-modification system could be related to phage resistance CLas during CLasMV1 infection. This study expands our knowledge of CLasMV1 that will benefit further CLas phage research and HLB control.