Alterations of the viroid regions that interact with the host defense genes attenuate viroid infection in host plant

Abstract

Understanding in intimate details how the viroid interaction with host's defense genes is a cornerstone for developing viroid resistant plants. In this present study, small RNAs (sRNA) derived from Potato spindle tuber viroid (PSTVd) were studied in silico in order to detect any interactions with the serine threonine kinase receptor, a transmembrane protein that plays a role in disease resistance in plants. Using molecular biology techniques, it was determined that PSTVd infection negatively affects at least three serine threonine kinase receptors as well as with three other genes that are known to be involved in the overall development of the tomato plants. The transient expression of these putative PSTVd-sRNAs, using the microRNA sequence as a backbone, in tomato plants induced phenotypes similar to viroid infection. Mutants created by altering the sequence of PSTVd in these regions failed to infect the tomato plant. The data presented here illustrates the importance of these regions in viroid survival, and suggests a possible avenue of exploration for the development of viroid resistant plants.

Small RNA-Omics for Plant Virus Identification, Virome Reconstruction, and Antiviral Defense Characterization

“…This indicates that viroid siRNAs form active RISCs that can potentially mediate both post-transcriptional and transcriptional silencing. Indeed, siRNAs derived from both nuclear and chloroplastic viroids can direct silencing of the host plant mRNAs through sequence-specific cleavage and degradation ( Navarro et al, 2012 ; Adkar-Purushothama et al, 2015 , 2018 ; Adkar-Purushothama and Perreault, 2018 ), although viroids can also indirectly impact on the host gene expression at both post-transcriptional and transcriptional levels ( Castellano et al, 2015 ; Tsushima et al, 2015 ; Torchetti et al, 2016 ; Zheng et al, 2017c ). Notably, nuclear viroids can also trigger de novo RNA-directed DNA methylation of the transgenes containing viroid sequences ( Wassenegger et al, 1994 ; Dalakouras et al, 2016 ).…”

Viroid‐derived small RNA induces early flowering in tomato plants by RNA silencing

“…The 21‐nucleotide sequence of PDS mRNA was synthesized by PCR and ligated into the binary vector pCV‐A under the control of the 35S promoter (pCV‐amiR:PDS). On agroinfiltration together with the pCV‐B vector, pCV‐amiR:PDS is capable of producing sRNA that can bind to its complementary sequence of PDS mRNA and trigger RNA silencing of the PDS gene, which, in turn, induces a bleaching effect (Adkar‐Purushothama and Perreault, ; Tang et al, ). At approximately 35 dpi, agroinfiltrated N. benthamiana plants exhibited bleaching of their leaves (Fig.…”

Current overview on viroid–host interactions

“…Additionally, the expression of a sequence corresponding to the PSTVd VMR that was predicted to target a soluble inorganic pyrophosphatase (siPPase) on an artificial miRNA in both Nicotiana tabacum and N. benthamiana induced abnormal phenotypes that are closely similar to what is seen in PSTVd infected plants (Eamens, Smith, Dennis, Wassenegger, & Wang, ). Using computer‐based target prediction algorithms coupled with molecular biology experiments, it was shown that a single vd‐sRNA is capable of inducing the RNA silencing of more than one host defense gene in a PSTVd‐tomato combination (Adkar‐Purushothama & Perreault, ). Several research groups have demonstrated the involvement of vd‐sRNAs in the down regulation of host genes using different approaches (summarized in Table ) (Adkar‐Purushothama et al, , ; Aviña‐Padilla et al, ; Aviña‐Padilla, Rivera‐Bustamante, Kovalskaya, & Hammond, ; Thibaut & Claude, ; Wang et al, ).…”