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Cucumber mosaic virus (CMV) and Alternariaspp. are among important and devastating plant pathogens with a wide host range. However, mixed infection of CMV and Alternariaspecies, is more common in greenhouses and fields. 2bis an important CMV gene that plays a critical role in CMV-host interactions and bZIP60is among the plant genes that affect by biotic stresses especially some plant viruses. In this research, the effect of silencing of 2b on bZIP60expression and resistance to A. atrawas evaluated. The results data showed induction of bZIP60in CMV infected plants by 18 folds while six-fold downregulation by A. atracompared to the healthy plants and also it showed a reduction in bZIP60expression to 1/2 fold in mixed infection plants in comparison with healthy plants. But transiently expression of 2b silencing gene construct in CMV infected plants reduced Alternaria necrosis leaf spot area and reduced the expression of bZIP60to 40 fold in mixed infected plants. However, the results of this research suggested the application of CMV-2b silencing construct for induction of resistance to both pathogens.

Chickpea (Cicer arietinumL.) is one of the most important legumes infected with many pathogens including fungal pathogens. One of the most important devastating fungal pathogens in chickpea is Ascochyta rabiei(Pass.) Labr. which causes up to 100% reduction in yield. In the present work, the expression patterns of AFP-ca, CaD2, LRRand PGIPgenes were studied in response to Ascochyta rabieiin two susceptible and resistant chickpea genotypes. The experimental system was conducted in greenhouse, for both inoculated and mock-inoculated plants (control). RNA was isolated from Icc 12004 (resistant) and FLIP 82-150c (susceptible) genotypes in 0, 6, 12, 24, 48, 72 and 96 h after inoculation. The expression of the genes was measured in susceptible and resistant plants via semiquantitative RT-PCR. Results showed higher expression of all three genes in resistant genotype compared with susceptible one. Results showed that the candidate genes from antimicrobial families (CaD2and AFP-ca) were up-regulated in resistant genotypes at early hours after inoculation (6–24 hpi), and also for PGIPfrom galacturonase-inhibiting protein families, the maximum expression was observed at early hours of inoculation to 48 hpi. In general, we concluded that all genes studied in this investigation contribute to plant–pathogen interaction and all of them can increase the resistance responses to Ascochyta blight disease.

The complete genome sequence of Zucchini yellow mosaic virusstrain Kurdistan (ZYMV-Kurdistan) infecting squash from Iran was determined from 13 overlapping fragments. Excluding the poly (A) tail, ZYMV-Kurdistan genome consisted of 9593 nucleotides (nt), with 138 and 211 nt at the 5′ and 3′ non-translated regions, respectively. It contained two open-reading frames (ORFs), the large ORF encoding a polyprotein of 3080 amino acids (aa) and the small overlapping ORF encoding a P3N-PIPO protein of 74 aa. This isolate had six unique aa differences compared to other ZYMV isolates and shared 79.6–98.8% identities with other ZYMV genome sequences at the nt level and 90.1–99% identities at the aa level. A phylogenetic tree of ZYMV complete genomic sequences showed that Iranian and Central European isolates are closely related and form a phylogenetically homogenous group. All values in the ratio of substitution rates at non-synonymous and synonymous sites (dN/dS) were below 1, suggestive of strong negative selection forces during ZYMV protein history. This is the first report of complete genome sequence information of the most prevalent virus in the west of Iran. This study helps our understanding of the genetic diversity of ZYMV isolates infecting cucurbit plants in Iran, virus evolution and epidemiology and can assist in designing better diagnostic tools.

One promising strategy to engineer plants that are resistant to plant pathogens involves transforming plants with RNA silencing constructs for resistance to multiple pathogens. Garden bean is significantly damaged by bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV) and cucumber mosaic virus (CMV). In this study, we prepared constructs producing sense, antisense and hairpin RNA (hpRNA) structures to target single as well as multiple viruses. Silencing efficiency of these constructions was analyzed using Agrobacterium (GV3101) transient expression in Nicothinia bethamianaand Phaseolus vulgarisplants. The results showed significantly reduced disease symptoms and virus accumulation in N. bethamianaplants. Generally, the efficiency of the prepared constructs was hairpin, antisense and sense, respectively, and also, there was a significant difference between mono-gene and multiple-gene constructs for reducng virus accumulation and the multiple-gene constructs showed higher effectiveness. Experiments in this study showed that using Agrobacterium harboring binary constructs containing a Caenorhabditis elegansgene, Ced-9, or a plant gene, AtBag-4, anti-apoptosis gene as a mix suspension with an Agrobacterium containing pFGC-BNC.h,a plasmid containing multiple gene fragments consisting of BCMV-CP, BCMNV-HC-Pro and CMV-2b, improved the efficiency of pFGC-BNC.htransformation. We showed reduced virus accumulation in these transgenic bean plans.