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A purple acid phosphatase, GmPAP2.1, from the soybean (Glycine max) cultivar L29 may function as a resistance factor acting against specific strains of Soybean mosaic virus (SMV). In this study, we found that overexpression of GmPAP2.1 from L29 conferred SMV resistance to a susceptible cultivar, Lee 74. We determined that GmPAP2.1 interacted with the SMV protein P1 in the chloroplasts, resulting in the up-regulation of the ICS1 gene, which in turn promoted the pathogen-induced salicylic acid (SA) pathway. SA accumulation was elevated in response to the co-expression of GmPAP2.1 and SMV, while transient knockdown of endogenous SA-related genes resulted in systemic infection by SMV strain G5H, suggesting that GmPAP2.1-derived resistance depended on the SA-pathway for the activation of a defense response. Our findings thus suggest that GmPAP2.1 purple acid phosphatase of soybean cultivar L29 functions as an SA-pathway-dependent resistance factor acting against SMV. [ABSTRACT FROM AUTHOR]

BACKGROUND: The sweetness of highbush blueberries is a sensory quality standard for consumers. Changes in metabolites and expression of associated genes induce variation in the sensory quality of blueberries. OBJECTIVE: This work investigated the ripening mechanism of blueberries by measuring changes in organic acids and sugar content as well as the gene expression levels associated with sugar accumulation, such as β amylase, invertase, sucrose phosphate synthase, and tonoplast monosaccharide transporter genes, before and after harvesting. METHODS: We used three different blueberry cultivars (Duke, Sierra, and Elizabeth) that we harvested at two ripening stages in a randomized complete block design and then kept at room temperature or 4°C for 7 days. The organic acids and sugar content were measured via HPLC, and gene expression levels were analyzed by qPCR. RESULTS: Cultivars, ripening stage, and storage conditions affected the synthesis of sugars and degradation of organic acids to determine the sweetness in blueberries and the expression of tagged genes and analyses of compounds involved in the metabolic mechanism. CONCLUSIONS: The results provide insights into the mechanism underlying the ripening and the postharvest quality. This study may support the selection of suitable blueberry cultivars that meet customer demand. [ABSTRACT FROM AUTHOR]

We have developed an efficient method to rapidly generate infectious inoculum of a plant RNA virus and confirmed its infectivity by mechanical inoculation. The method takes advantage of overlap PCR to bypass the cloning steps, which makes it relatively simple, rapid, and inexpensive compared to the traditional methods. Using this approach, inoculum of a tobamovirus, Turnip vein clearing virus (TVCV), was generated. PCR products specific for the 35S promoter and TVCV genome were used as templates for overlap PCR to form a single product containing the full-length TVCV cDNA under the control of the double 35S promoter, and the entire process took only 8 h. This inoculum was infectious in Nicotiana benthamiana , and its infectivity was ca. 67% compared to 0% and 100% with negative and positive controls, respectively. Thus, this rapid method generates efficient infectious inoculum for a plant RNA virus. • Fusion of 35S promoter and TVCV was rapidly created by overlap PCR. • Infectivity of the fusion construct was confirmed by mechanical inoculation in Nicotiana benthamiana. • A recombinant TVCV expressing GFP was rapidly generated by our method. [ABSTRACT FROM AUTHOR]

Autonomous hypersensitive responses (self-HRs) are caused by constitutively active R proteins. In this study, we identified an auto-activated form of the R gene Pvr9 (autoPvr9); the auto-activation results from an amino acid substitution between its NBS and LRR domains. Self-HR was strongly reduced or completely inhibited by fusion of an extra peptide to the autoPvr9 N-terminal or C-terminal, respectively. When an NIa recognition site was placed between autoPvr9 and the extra peptide, the fusion construct could trigger an NIa-dependent HR. Several C-terminal fusions were tested, but only those that maintained detectable protein expression were capable of an NIa-dependent HR. Our results suggest the potential for transforming malfunctioning and auto-activated R proteins into a new construct targeting potyviral NIa proteases. [ABSTRACT FROM AUTHOR]

Resistance to pathogens mediated by plant resistance (R) proteins requires different signaling transduction components and pathways. Our previous studies revealed that a potyvirus resistance gene in pepper, Pvr9 , confers a hypersensitive response (HR) to pepper mottle virus in Nicotiana benthamiana . Our results show that the Pvr9 -mediated HR against pepper mottle virus infection requires HSP90, SGT1, NDR1 , but not EDS1. These results suggest that the Pvr9 -mediated HR is possibly related to the SA pathway but not the ET, JA, ROS or NO pathways. [ABSTRACT FROM AUTHOR]

Tomato (Lycopersicum esculentum L.) and pepper (Capsicum annuum L.) plants belonging to the family Solanaceae are cultivated worldwide. The rapid development of next-generation sequencing (NGS) technology facilitates the identification of viruses and viroids infecting plants. In this study, we carried out metatranscriptomics using RNA sequencing followed by bioinformatics analyses to identify viruses and viroids infecting tomato and pepper plants in Vietnam. We prepared a total of 16 libraries, including eight tomato and eight pepper libraries derived from different geographical regions in Vietnam. We identified a total of 602 virus-associated contigs, which were assigned to 18 different virus species belonging to nine different viral genera. We identified 13 different viruses and two viroids infecting tomato plants and 12 viruses and two viroids infecting pepper plants with viruses as dominantly observed pathogens. Our results showed that multiple infection of different viral pathogens was common in both plants. Moreover, geographical region and host plant were two major factors to determine viral populations. Taken together, our results provide the comprehensive overview of viral pathogens infecting two important plants in the family Solanaceae grown in Vietnam. [ABSTRACT FROM AUTHOR]