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Pistachio (Pistacia vera L.) is a perennial woody plant that produces edible seeds with a high nutritional value. Canker disease is one of the important diseases of pistachio, causing considerable loss globally. During 2019–2021, a series of symptoms, including tree weakness, brown to black lesions, canker, and exudation of black sap were observed on the trunk of pistachio trees from different regions of Lorestan province, western Iran. Bacterial isolation resulted in the development of uniform and yellow colonies on yeast-extract peptone glucose agar (YPGA) medium 24 hours post-inoculation (hpi). The colonies were then purified on YPGA and yeast-extract-dextrose-calcium-carbonate agar (YDC). Based on the analysis of morphological, biochemical, and molecular characteristics using nucleotide sequences of the gyrB, infB, atpD, and 16S rRNA, a putative pathogen was identified as Pantoea agglomerans (formerly Enterobacter agglomerans). To fulfill Koch's postulates, bacterial suspensions (107 CFU/ml) were inoculated to one-year-old pistachio seedlings. Thirty days after inoculation, small necrotic lesions developed on the bark in the vicinity of inoculation sites, followed by brown necrotic streaks in the inner bark. Subsequently, the bacterial strains exhibiting the characteristic colony morphology were retrieved from lesions on inoculated pistachio seedlings and verified as P. agglomerans. To the best of our knowledge, this is the first report on the occurrence of pistachio canker caused by P. agglomerans.

Mycopathogenic bacteria play a pivotal role in the productivity of edible mushrooms grown under controlled conditions. In this study, we carried out a comprehensive farm survey and sampling (2018 to 2021) on button mushroom ( Agaricus bisporus) farms in 15 provinces in Iran to monitor the status of bacterial pathogens infecting the crop. Mycopathogenic bacterial strains were isolated from pins, stems, and caps, as well as the casing layer on 38 mushroom farms. The bacterial strains incited symptoms on mushroom caps ranging from faint discoloration to dark brown and blotch of the inoculated surfaces. Among the bacterial strains inciting disease symptoms on bottom mushroom, 40 were identified as Ewingella americana based on biochemical assays and phylogeny of 16S rRNA and the gyrB gene. E. americana strains differed in their aggressiveness on mushroom caps and stipes, where the corresponding symptoms ranged from deep yellow to dark brown. In the phylogenetic analyses, all E. americana strains isolated in this study were clustered in a monophyletic clade closely related to the nonpathogenic and environmental strains of the species. BOX-PCR-based fingerprinting revealed intraspecific diversity. Using the cutoff level of 73 to 76% similarity, the strains formed six clusters. A chronological pattern was observed, where the strains isolated in 2018 were differentiated from those isolated in 2020 and 2021. Taken together, due to the multifaceted nature of the pathogen, such a widespread occurrence of E. americana on mushroom farms in Iran could be an emerging threat for the mushroom industry in the country.

Citrus Bacterial Canker disease, caused by Xanthomonas citri subsp. citri (Xcc), is one of the most devastating diseases that attacks citrus, especially in the southern areas of Iran. The objective of this investigation was to analyze several characteristics involved in Xcc virulence in relation to strain aggressiveness. To achieve this, swarming motility, biofilm formation, resistance to H2O2, and production of xanthan were evaluated considering 44 local strains causing citrus bacterial canker disease in Iran. All strains showed differential swarming motilities, biofilm formation abilities, and xanthan production. The most virulent strain, Xcc-KVXCC1, exhibited the greatest capability to form biofilm on solid surfaces, xanthan production, and pathogenicity on detached leaves of Citrus aurantifolia as well as positive chemotaxis toward C. aurantifolia extract. In this study, a total of 14 common and commercial citrus genotypes were evaluated for resistance to Xcc-KVXCC1. Genotypes were categorized into susceptible and resistant groups based on lesion number per inoculation site. Based on our results, C. aurantifolia was the most susceptible citrus cultivar to Xcc-KVXCC1. In contrast, C. aurantium, C. jumbhori, and C. reticulata cv. ponkan demonstrated high and moderately high resistance against Xcc-KVXCC1.

Ficus benjamina, commonly known as weeping fig, Benjamin’s fig or Ficus tree is a species of flowering plant in the family of Moraceae. It is native to south and south-east Asia and Australia. Crown gall tumours were collected from branches of one-year-old weeping fig (F. benjamina L.) trees. A total of 50 strains of Agrobacterium tumefaciens were isolated from diseased Ficus plants and their morphological, molecular and biochemical characteristics were studied; pathogenicity tests on tomato, F. benjamina and Bryophyllum daigremontianum were also conducted. Based on the biochemical characteristics, pathogenicity test and PCR amplification of 730 bp fragment using VCR\VCF primers, the tested bacterial strains were identified as A. tumefaciens. This is the first report of crown gall on F. benjamina in Isfahan and Fars provinces of Iran.

Septoria tritici blotch is an important wheat disease in many areas of the world including Iran’s warm, humid regions. In this study, reaction of 79 lines from elite regional wheat yield trials of the Cereal Research Department from four climate zones was evaluated to S. tritici leaf blotch in adult plant stage under an artificial field inoculation in Khuzestan province in the south of Iran for two years (2008–2009 and 2009–2010). Nurseries were artificially inoculated by spreading infected plant debris (from last growing season). Taking notes was performed with a modified Saari and Prescott method in 00–99 double-digit scale. Wheat lines were classified in groups of immune (00), highly resistant (11–14), resistant (15–34), moderately resistant (35–44), moderately susceptible (45–64), susceptible (65–84) and highly susceptible (85–99). Result showed that from 79 lines, 37 lines had susceptible reaction; 2 lines had moderately susceptible; and 40 lines showed immune.

Wheat yellow (stripe) rust, caused by the fungus Puccinia striiformis f. sp. tritici, is an important disease in most of the wheat-growing parts of Iran. Use of resistant cultivar is the best method to control the disease. This study was carried out to identify the virulence factors of stripe rust in Khuzestan province in south of Iran (warm zone) for 2 years (2010–2011 and 2011–2012) and use this information in the breeding programme. For this purpose, the trap nursery was included 41 lines of standard sets of stripe rust with different gene and Bolani and morocco as susceptible check. In the flag leaf stage when the susceptible check (Bolani and morocco) was 90–100S (Susceptible), all lines were scored for stripe rust. Data showed that virulence for genes included Yr6, Yr7, Yr9, Yr27 and YrA. For genes Yr1, Yr3, Yr4, Yr5, Yr8, Yr10, Yr15, YrCV, YrND, YrSU, YrSP and YrSD, virulence was not detected.

Chinaberry (Melia azedarach) is a deciduous tree of moderate size, grown throughout warm countries. The plantation of M. azedarach tree improves the environmental condition of the country. During the years 1390–1391, bacterial gall symptoms were observed on chinaberry. The isolation of the causal agent bacteria was done on nutrient agar medium. Approximately 4 weeks after inoculation, galls developed on the chinaberries inoculated with different isolates. The specific primer was designed based on 16S rRNA gene and all isolates amplified 429 bp fragment. To sequence 16S rRNA gene of Shiraz isolates, the universal primer PS16Sf-FAM/PS23Sr was used to amplify 16S rRNA gene. The Iranian isolates of Pseudomonas meliae showed 99.7% similarity to P. meliae (type strain) in the Gene Bank. Based on the rep-PCR results and sequence of 16S rRNA gene, Pseudomonas syringae and Pseudomonas fluorescens were placed in the different groups.