مجلة جامعة كركوك للعلوم الزراعية (Jun 2022)
Phenotypic and molecular diagnosis of some fungi that cause spikes blight on barley in Salah al-Din and Nineveh governorates
Abstract
The results of the field survey showed that when the head blight disease was investigated on barley for the barley cultivation areas in the governorates of Salah al-Din and Nineveh, the disease spread in varying proportions, the number of fields affected by the disease (examination appearance) 17 fields out of 21 fields included in the survey process, and the infection rate in the fields ranged between 3.2 - 4.7 %, with an average of 2.9 %, and a severity of infection ranging between 0.3 - 0.9 %, and an average of 0.7%. The data related to the percentages of isolates from ears and barley plants showed a higher frequency of appearance of spp Fusarium species compared to isolates of other fungi. The highest frequency of appearance of F. graminearum reached 20% of the adult plant and 35% of the ears were followed by F. culmorum with a rate of approximately 15% of the plants And 20% of the spikes, followed by the type F. poae with 15% of the plants and 10% of the spikes, and other genera appeared with the fungul Fusarium spp in the emergence and the highest percentage of the appearance of the fungus Alternaria spp and by 25% on the adult plants and 20% on the spikes Then the fungus Aspergillus spp followed with a percentage of 5% on adult plants and 10% on spikes, and Helminthosporum spp with 5% on adult plants, while it appeared on spikes by 10%. After purification of the colonies, we noticed the presence of colonies of white color in general with a pink color, which changed with the age of the colony to brown, forming a fungal pillow with limited formation when growing on the middle of the Carnation Leaf Agar (CLA) leaves. The inverted plate was pale orange in color. Also, Macroconidia spores appeared under the microscope, curved and thin on its dorsal side, and the spores were thin, with thick walls, of medium lengths, and curved or straight on their ventral side, their basal cell distinct and the apical almost tapering. The number of septa in large spores ranged between 3 to 7 septa. Chlamydial spores of fungi are different in their composition, and the slow-forming spores are often the most common ones that form on large conidia, as they were formed in the mycelium single with dimensions between 10-12 micrometers. Colonies of `red color tend to brown and Macrocondia strong and somewhat short and surrounded by thick walls, the dorsal side is relatively curved, and the ventral side is almost straight. clove. Conidia runners are branched on mycelium of mushrooms that assemble and form the pillow-shaped Sporodochium. The shape is oval and tends to be spherical. It is characterized by Chlamydia spores, which are formed between the cells of the mycelium of the fungus or on both ends. Its texture is soft to rough, and the dimensions range from 9-13 micrometers, and they are singly or aggregated, giving the form of chains. Molecular diagnosisof the fungal isolates that caused head blight in barley fields, F. graminearum and F. culmorum, was confirmed using polymerase chain reaction (PCR) technology by using a pair of specialized primers to detect genes in the internal transcribed spacer ( ITS) ITS in which the forward initiator (ITS1 F: 5′- TCCGTAGGTGAACCTGCGG-3′) and the reverse initiator (ITS4 R: 5′ TCCTCCGCTTATTGATATGC-3′) were used. The results of electro-migration analysis using 2% agarose showed that a band of size 544 base pairs appeared, which is the size that was expected at which the specialized primers appear for detection. Because the initiators are located within the genetic makeup of F.graminearum and F. culmorum. It is finally confirmed that the two isolates of mushrooms that were diagnosed by phenotypic diagnosis on culture media belong to the two fungi mentioned above
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