Nuclear proteome of virus-infected and healthy potato leaves

Abstract Background Infection of plants by viruses interferes with expression and subcellular localization of plant proteins. Potyviruses comprise the largest and most economically damaging group of plant-infecting RNA viruses. In virus-infected cells, at least two potyviral proteins localize to nucleus but reasons remain partly unknown. Results In this study, we examined changes in the nuclear proteome of leaf cells from a diploid potato line (Solanum tuberosum L.) after infection with potato virus A (PVA; genus Potyvirus; Potyviridae) and compared the data with that acquired for healthy leaves. Gel-free liquid chromatography–coupled to tandem mass spectrometry was used to identify 807 nuclear proteins in the potato line v2–108; of these proteins, 370 were detected in at least two samples of healthy leaves. A total of 313 proteins were common in at least two samples of healthy and PVA-infected leaves; of these proteins, 8 showed differential accumulation. Sixteen proteins were detected exclusively in the samples from PVA-infected leaves, whereas other 16 proteins were unique to healthy leaves. The protein Dnajc14 was only detected in healthy leaves, whereas different ribosomal proteins, ribosome-biogenesis proteins, and RNA splicing–related proteins were over-represented in the nuclei of PVA-infected leaves. Two virus-encoded proteins were identified in the samples of PVA-infected leaves. Conclusions Our results show that PVA infection alters especially ribosomes and splicing-related proteins in the nucleus of potato leaves. The data increase our understanding of potyvirus infection and the role of nucleus in infection. To our knowledge, this is the first study of the nuclear proteome of potato leaves and one of the few studies of changes occurring in nuclear proteomes in response to plant virus infection

Differential Requirement of the Ribosomal Protein S6 and Ribosomal Protein S6 Kinase for Plant-Virus Accumulation and Interaction of S6 Kinase with Potyviral VPg

Ribosomal protein S6 (RPS6) is an indispensable plant protein regulated, in part, by ribosomal protein S6 kinase (S6K) which, in turn, is a key regulator of plant responses to stresses and developmental cues. Increased expression of RPS6 was detected in Nicotiana benthamiana during infection by diverse plant viruses. Silencing of the RPS6and S6K genes in N. benthamiana affected accumulation of Cucumber mosaic virus, Turnip mosaic virus (TuMV), and Potato virus A (PVA) in contrast to Turnip crinkle virus and Tobacco mosaic virus. In addition, the viral genome-linked protein (VPg) of TuMV and PVA interacted with S6K in plant cells, as detected by bimolecular fluorescence complementation assay. The VPg–S6K interaction was detected in cytoplasm, nucleus, and nucleolus, whereas the green fluorescent protein-tagged S6K alone showed cytoplasmic localization only. These results demonstrate that the requirement for RPS6 and S6K differs for diverse plant viruses with different translation initiation strategies and suggest that potyviral VPg–S6K interaction may affect S6K functions in both the cytoplasm and the nucleus

Nuclear proteome of virus-infected and healthy potato leaves

BackgroundInfection of plants by viruses interferes with expression and subcellular localization of plant proteins. Potyviruses comprise the largest and most economically damaging group of plant-infecting RNA viruses. In virus-infected cells, at least two potyviral proteins localize to nucleus but reasons remain partly unknown.ResultsIn this study, we examined changes in the nuclear proteome of leaf cells from a diploid potato line (Solanum tuberosum L.) after infection with potato virus A (PVA; genus Potyvirus; Potyviridae) and compared the data with that acquired for healthy leaves. Gel-free liquid chromatography-coupled to tandem mass spectrometry was used to identify 807 nuclear proteins in the potato line v2-108; of these proteins, 370 were detected in at least two samples of healthy leaves. A total of 313 proteins were common in at least two samples of healthy and PVA-infected leaves; of these proteins, 8 showed differential accumulation. Sixteen proteins were detected exclusively in the samples from PVA-infected leaves, whereas other 16 proteins were unique to healthy leaves. The protein Dnajc14 was only detected in healthy leaves, whereas different ribosomal proteins, ribosome-biogenesis proteins, and RNA splicing-related proteins were over-represented in the nuclei of PVA-infected leaves. Two virus-encoded proteins were identified in the samples of PVA-infected leaves.ConclusionsOur results show that PVA infection alters especially ribosomes and splicing-related proteins in the nucleus of potato leaves. The data increase our understanding of potyvirus infection and the role of nucleus in infection. To our knowledge, this is the first study of the nuclear proteome of potato leaves and one of the few studies of changes occurring in nuclear proteomes in response to plant virus infection.Peer reviewe

Protocol: Optimised methodology for isolation of nuclei from leaves of species in the Solanaceae and Rosaceae families

Peer reviewe

Differential Requirement of the Ribosomal Protein S6 and Ribosomal Protein S6 Kinase for Plant-Virus Accumulation and Interaction of S6 Kinase with Potyviral VPg

Ribosomal protein S6 (RPS6) is an indispensable plant protein regulated, in part, by ribosomal protein S6 kinase (S6K) which, in turn, is a key regulator of plant responses to stresses and developmental cues. Increased expression of RPS6 was detected in Nicotiana benthamiana during infection by diverse plant viruses. Silencing of the RPS6and S6K genes in N. benthamiana affected accumulation of Cucumber mosaic virus, Turnip mosaic virus (TuMV), and Potato virus A (PVA) in contrast to Turnip crinkle virus and Tobacco mosaic virus. In addition, the viral genome-linked protein (VPg) of TuMV and PVA interacted with S6K in plant cells, as detected by bimolecular fluorescence complementation assay. The VPg–S6K interaction was detected in cytoplasm, nucleus, and nucleolus, whereas the green fluorescent protein-tagged S6K alone showed cytoplasmic localization only. These results demonstrate that the requirement for RPS6 and S6K differs for diverse plant viruses with different translation initiation strategies and suggest that potyviral VPg–S6K interaction may affect S6K functions in both the cytoplasm and the nucleus.This article is published as Rajamäki, Minna-Liisa, Dehui Xi, Sidona Sikorskaite-Gudziuniene, Jari PT Valkonen, and Steven A. Whitham. "Differential Requirement of the Ribosomal Protein S6 and Ribosomal Protein S6 Kinase for Plant-Virus Accumulation and Interaction of S6 Kinase with Potyviral VPg." Molecular Plant-Microbe Interactions 30, no. 5 (2017): 374-384. doi: 10.1094/MPMI-06-16-0122-R. Posted with permission.</p

Integration of Ultrasound into the Development of Plant-Based Protein Hydrolysate and Its Bio-Stimulatory Effect for Growth of Wheat Grain Seedlings In Vivo

This study was dedicated to increasing the efficiency of producing plant-based protein hydrolysate using traditional and non-traditional treatments. Low- and high frequency ultrasound (US) at different intensities were applied to corn steep liquor (CSL) at 50 °C for 30 min, and enzymatic hydrolysis was performed using industrially produced alkaline protease. The efficiency of US and enzymatic treatments was characterized by protein solubility (soluble protein (SP) content, hydrolyzed protein (HP) concentration, and free amino acid (FAA) profile) and kinetic parameters: Michaelis–Menten constant (KM) and apparent breakdown rate constant (kA). A significant effect of 37 kHz US pre-treatment for CSL enzymatic hydrolysis was found and resulted in the highest HP concentration (17.5 g/L) using the lowest enzyme concentration (2.1 g/L) and the shortest hydrolysis time (60 min). By using US pre-treatment, on average, a 2.2 times higher FAA content could be achieved compared to traditional hydrolysis. Additionally, results for the kinetic parameters kM and kA confirmed the potential of applying US treatment before hydrolysis. The effect of CSL protein hydrolysate on plant growth was tested in vivo on wheat grain seed germination and resulted in the significant increase in germination parameters compared to the control treatment. These findings indicate that by-products of starch industry could be a promising source for the production of low-cost sustainable biostimulants