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Fusarium wilt is one of the most severe diseases of chickpea in the major growing areas of chickpea production in western Iran. To identify Fusarium spp. associated with chickpea plants showing symptoms of yellowing and wilting, 58 chickpea fields were sampled and 106 Fusarium spp. isolates were obtained from six different regions of Kermanshah Prov- ince in western Iran during 2018 and 2019 crop seasons. Thirty-six isolates obtained from stem or lower stem tissues were selected for pathogenicity, morphological and molecular identification using polymease chain reaction species-specific primers. Eleven isolates of Fusarium spp. were selected for sequence analyzing the translation elongation factor 1-α (EF-1α), and β-tubulin gene regions. Phylogenetic analysis of concatenated DNA sequences of both gene regions of these isolates plus other taxa revealed that 11 Fusarium spp. isolates were clustered into five distinct groups. Based on the results of morphological and mo- lecular identification five Fusarium species were identified. Pathogenicity tests showed that F. oxysporum f. sp. ciceris and F. redolens isolates had the highest disease incidence on JG–62 and Bivenij cvs. and F. hostae, F. equiseti and F. acuminatum isolates had the lowest disease incidence. No sign of vascular discoloration was observed in longitudinal or transverse sections of chickpea plants affected by F. redolens isolates. Instead, brown to black necrosis was observed on the surface of tap-roots and crowns. No correlation was found between geographical distribution and pathogenicity of isolates. This is the first report of morpho- logical, molecular and pathogenicity characteristics of F. redolens and F. hostae isolated from chickpea stems or lower stems in Iran.

Brown spot (BS), caused by Bipolaris oryzae, is one of the most important fungal diseases in rice-growing regions of the world. Identification of genomic regions associated with BS-related traits is essential for improving BS resistance in rice. In this study, the population structure and the association mapping between simple sequence repeat (SSR) markers and BS-related traits were assessed in 95 rice genotypes under nursery and field conditions. Genetic analysis indicated that RM3739 and RM7576 had the highest level of diversity indices including number of alleles, number of effective alleles, polymorphic information content value, gene diversity, and Shannon’s information index, which can be useful for other rice breeding programs. A high genetic diversity was found between genotypes, which can be exploited to improve and produce rice cultivars for important traits. Population structure analysis using model-based and distance-based approaches grouped the genotypes into two distinct sub-populations. Association analysis was conducted through the general linear model (GLM) and the mixed linear model (MLM). Using the GLM, 35 and 27 markers were significantly associated after considering Bonferroni correction with BS resistance at the seedling and adult plant stages, respectively, in both 2017 and 2018. Moreover, the significantly associated markers were reduced to 14 and 3 at the seedling and adult plant stages, respectively, by MLM. RM6499 was associated with nursery and field resistance to BS in both GLM and MLM, suggesting that this marker can be used in breeding programs for development of improved BS-resistant rice varieties through marker-assisted selection.

In this study, apple fruits were first treated with different concentrations (1.5, 3, 4.5 and 6×1000) of walnut green skin water extract and Penicillium expensum pathogen. The activity of defense enzymes including of phenylalanine ammonia-lyase, polyphenol oxidase, superoxide dismutase and β(1,3) glucanase were measured in the treated apple fruits in the sampling days, 3, 6, 9, 12, and 15 days after pathogen induction of fruit. Then, genes expression levels encoding these enzymes were assessed by Real-time PCR. The results showed that the activity of the studied enzymes increased from the third day of sampling to the 9th day and then decreased until the 15th day. Pathogen and walnut green skin both increased the enzyme activity. As the concentration of the walnut green skin extracts increased, the activity of the enzymes increased. The highest activity of PAL, PPO, SOD and Glu enzymes was observed at day 9 at concentrations of 6×1000 with values 11.28 (U per mg protein), 5.37 (∆OD per min per mg of total protein), 26.87 (U per mg mg protein) and 23.89 (∆OD per min per mg of total protein), respectively. The results of measurement of gene expression were also in accordance with the activity of enzymes. Exactly on the 9th day, the highest gene expression was observed for the genes expressing each enzyme and in the treatment of both pathogens and extracts. The gene expression levels of PAL, PPO, SOD and Glu enzymes at 9th day and in apple treated with pathogen and green walnut skin extracts were 121, 148, 150 and 148 times higher than those genes in the healthy apples as control, respectively.

Since embryogenesis, plants deal with environmental changes, which might affect their growth and development. Plant autophagy has been shown to function in various stress responses, immunity, development, and senescence. Acquired thermotolerance or thermopriming is enhanced resistance to the elevated temperature following heat stress.Potential contribution of autophagy mechanism after thermopriming was investigated in shoot apical meristem (SAM) ofTranscriptic expression of Autophagy related Genes (Expression patterns of 39 ATGs and ATG-receptors were described and relevant thermopriming induced autophagy genes were identified according to their highest expression fold changes during the time after treatment. Significantly,Autophagy, a conserved mechanism for cell survival in plants will be activated in response to the thermopriming which is a promoted acquired resistance stimulus. Determined key genes and components of autophagy associated with thermal priming signaling pathway could be noteworthily employed to study transcriptional regulation of autophagy and integrated defense system against environmental stresses for the improvement of plant thermal tolerance and resistance to the pathogens.

The nursery resistance of 95 rice genotypes to brown spot (BS) was evaluated under water stress and irrigated conditions during 2017 and 2018. Disease assessment was done by calculating the final b...

Antioxidant enzymes play an important role in plant defense against pathogenic agents. Following the identification of the pathogen, plants produce active oxygen species (ROS) as one of their first defense responses. To maintain the balance of ROS levels and prevent their harmful effects, plants produce antioxidant peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes. In the present study, the resistance of bean plants cultivars, namely Sadri, Paak, Darakhshan and Dorsa, to Xanthomonas axonopodis pv. phaseoli (Xap) were studied in greenhouse conditions. The catalase, peroxidase and ascorbate peroxidase enzyme activities were studied in healthy and Xap-infected bean cultivars Sadri and Derakhshan at 0, 24, 48, 72 hours and 20 days post inoculation by a completely randomized design with 5 treatments and 4 replications. The result showed that disease symptoms appeared in all tested cultivars. Derakhshan and Sadri cultivars, with 58.33 and 80.56 percentages of infected plants 20 days after inoculation, showed the least and highest infection rates, respectively. The highest catalase and peroxidase activities were recorded 24 and 48h post inoculation. These records reduced 48 and 72 hours post inoculation, respectively. The activities of these two enzymes in the susceptible cultivar were less than those in the semi-resistant one. The chlorophyll a and chlorophyll b contents of Xap-infected plants reduced significantly. The total chlorophyll content of uninfected Sadri and Darakhshan cultivars were 2.93 and 3.23 µg/g, respectively, which reduced to 1.96 and 2.14 µg/g of leaf tissue in infected plants, respectively. Based on these results, it is suggested that the Derakhshan cultivar should be planted in disease-susceptible regions as the semi-resistant cultivar.

SummaryBread wheat,Triticum aestivum, produces large edible grains and is consumed by 75% of the world’s populations. Cereal cyst nematodes have a global distribution and cause significant economic yield losses in many countries. Therefore, there is an urgent need to identify new resistance sources. In this study, the genetic diversity of 43 wheat accessions in response to cereal cyst nematode,Heterodera filipjeviIsfahan pathotype, was assessed using a simple sequence repeat (SSR) marker. Seven primers were used, out of which five primers showed polymorphisms. Alleles per primer varied from one to three per locus (mean 2.85). The highest and lowest polymorphic information content of 0.81 and 0.44 (mean 0.66) were related to Xgwm 3012DL and Xgwm147, respectively. Genetic similarity was 29-88% between accessions. SSR analysis divided the accessions into five main groups. Resistant cultivars ‘Bam’ and ‘Behrang’ possessed bothCre1 andCre8 resistant genes. TheCre3 andCatgenes were partially sequenced in five cultivars of different responses toH. filipjevi. The nucleotide sequences were compared toCre3 andCathomologues, indicating 93-100% and 86-92% homology, respectively. The MEGA program showed highest similarity ofCre3 andCatgenes amplified with the resistance gene analogues (RGA14) in the wheat andCat3-A1 gene in ‘Carnamah’. This research showed that SRR markers could efficiently verify genetic diversity between wheat accessions, and the known resistance genes (Cregenes) against the cereal cyst nematodes could not control theH. filipjeviIsfahan pathotype populations, except theCre1 gene.

The antagonistic potential of forty isolates of Trichoderma spp. obtained from major chickpea growing areas in western part of Iran, were evaluated against Fusarium oxysporum f. sp. ciceris, the most important soil-born pathogen of chickpea. Among those, six species of Trichoderma harzianum, T. longibrachiyatum, T. pleurotum, T. crassum, T. guizhouense ,and Trichoderma sp. were identified based on morphological, molecular and phylogenetic analysis of concatenated DNA sequences of tef1 and rpb2 genes. All isolates were tested in vitro using dual culture method for their inhibition of the mycelial growth of the pathogen. Eight most antagonistic isolates, which suppressed colony growth of pathogen by 61.1-65.5%, were tested in vitro for production of volatile metabolites. All eight selected isolates produced volatile metabolites which prevented radial growth of pathogen from 17.5% to 31.0%. Antagonistic isolates provided significant protection against pathogen when mixed with soil or treated on seeds. Wilt control efficiency was greater for T. longibrachyatum KT8 (64.4%), T. harzianum KT9 (66.1%), and KT10 (69.5%) after 60 days of sowing highly susceptible chickpea cultivar JG-62 in inoculated soils. Greater wilt control efficiencies were detected for seed treatments with KT8 (69.1%), KT9 (72.7%), and KT10 (74.5%) isolates. Higher plant height, dry weight of root and shoot were recorded with these three superior isolates in seed treatments, inoculated, and non-inoculated soils. Such superior isolates could be considered as promising antagonistic agents in biocontrol of chickpea Fusarium wilt for future studies. To the best of our knowledge, T. pleurotum and T. guizhouense are reported for the first time from Iran.

Wheat take-all disease, caused by Gaeumannomyces graminis var tritici (Ggt), has been observed in different areas of Iran in recent years. Current biocontrol studies have confirmed the effectiveness of theTrichoderma species against many fungal phytopathogens. In this study, biocontrol effects of Trichoderma isolates were evaluated against take-all pathogen. Five (Trichoderma virens T65, Trichoderma virens T90, Trichoderma virens T96, Trichoderma virens T122 and Trichoderma koningii T77) isolates were selected after screening tests for antifungal effects against take-all pathogen and three (Trichoderma koningiopsis T149, Trichoderma brevicompactum T146 and Trichoderma viridecens T150) isolates were used as random selection. Also, Trichodermin B and Subtilin as commercial bioproducts were also used to evaluate biocontrol effects against take-all in greenhouse. In dual culture tests, five (T65, T90, T96, T122 and T77) isolates covered and colonized the colony of the pathogen. Microscopic studies revealed hyphal coiling (hyperparasitism) of isolates T65, T96 and T90 around Ggt hyphae. Culture filtrates and volatile metabolites of all isolates reduced the mycelial growth of take-all pathogen. T96, T65, mixture of eight isolates and Trichodermin B were more effective than other treatments to control the disease and reduced 25 to 55% disease severity and increased 27 to 59% dry weight of shoots and 23 to 58% dry weight of roots compared with control while disease reduction ofseed coating method was more than soil treatment application. Although, based on shoots and roots dry weight, all of treatments showed significant differences with healthy plants.