Modulation of Expression of PVYNTN RNA-Dependent RNA Polymerase (NIb) and Heat Shock Cognate Host Protein HSC70 in Susceptible and Hypersensitive Potato Cultivars

Abstract

Potato virus Y (PVY) belongs to the genus Potyvirus and is considered to be one of the most harmful and important plant pathogens. Its RNA-dependent RNA polymerase (RdRp) is known as nuclear inclusion protein b (NIb). The recent findings show that the genome of PVY replicates in the cytoplasm of the plant cell by binding the virus replication complex to the membranous structures of different organelles. In some potyviruses, NIb has been found to be localized in the nucleus and associated with the endoplasmic reticulum membranes. Moreover, NIb has been shown to interact with other host proteins that are particularly involved in promoting the virus infection cycle, such as the heat shock proteins (HSPs). HSP70 is the most conserved among the five major HSP families that are known to affect the plant–pathogen interactions. Some plant viruses can induce the production of HSP70 during the development of infection. To understand the molecular mechanisms underlying the interactive response to PVYNTN (necrotic tuber necrosis strain of PVY), the present study focused on StHSC70-8 and PVYNTN-NIb gene expression via localization of HSC70 and NIb proteins during compatible (susceptible) and incompatible (hypersensitive) potato–PVYNTN interactions. Our results demonstrate that NIb and HSC70 are involved in the response to PVYNTN infections and probably cooperate at some stages of the virus infection cycle. Enhanced deposition of HSC70 proteins during the infection cycle was associated with the dynamic induction of PVYNTN-NIb gene expression and NIb localization during susceptible infections. In hypersensitive response (HR), a significant increase in HSC70 expression was observed up to 3 days post-inoculation (dpi) in the nucleus and chloroplasts. Thereafter, between 3 and 21 dpi, the deposition of NIb decreased, which can be attributed to a reduction in the levels of both virus accumulation and PVYNTN-NIb gene expression. Therefore, we postulate that increase in the expression of both StHSC70-8 and PVYNTN-NIb induces the PVY infection during susceptible infections. In contrast, during HRs, HSC70 cooperates with PVYNTN only at the early stages of interaction and mediates the defense response signaling pathway at the later stages of infection.

AtGSTU19 and AtGSTU24 as Moderators of the Response of Arabidopsis thaliana to Turnip mosaic virus

“…Briefly, leaf samples (0.1 g of each sample) were collected from 25 mock- (buffer) or virus-infected plants of different types of Col-0 and mutant plants. RNA isolation, purification, and quality analyses were carried out following previously described procedures [ 16 , 99 , 100 ]. In addition, the absence of RNA contamination was verified by performing reverse transcription PCR using AtEf1α ( A. thaliana elongation factor-1 alpha) and AtF-Box ( A. thaliana F-Box protein family) as reference standards [ 98 ], which confirmed the absence of contaminating gDNA.…”

Glutathione Modulation in PVYNTN Susceptible and Resistant Potato Plant Interactions

“…Briefly, leaf samples (0.1 g of each sample) were collected from 30 mock (buffer) or virus infected seedlings per cultivar at 3, 7, and 21 dpi. RNA isolation, purification, and quality analyses were carried out as described previously [ 39 , 79 ]. Additionally, the absence of RNA contamination was verified by performing reverse transcription-polymerase chain reaction using StEf1α ( S. tuberosum elongation factor-1 alpha) and Stsec3 (exocyst complex component) as the reference standard [ 39 , 80 ], which confirmed the absence of contaminating gDNA.…”

Binding immunoglobulin 2 functions as a proviral factor for potyvirus infections in Nicotiana benthamiana

“…The association of Hsc70‐3 and NIb could occur in membrane‐derived replication complexes (Dufresne, Thivierge, et al, 2008 ; Dufresne, Ubalijoro, et al, 2008 ). Correspondingly, a study on the NIb of another potyvirus, potato virus Y strain necrotic tuber necrosis (PVY NTN ), demonstrated its interaction with Hsc70, resulting in susceptibility to PVY NTN (Kozieł et al, 2021 ). Given that interaction between NIb and host factors primarily results in infection, there is a high possibility that NIb is recruiting these host factors into the viral replication complex (VRC) for virus multiplication (Shen et al, 2020 ).…”