Seed to Plant to Seed Transmission of Wheat Blast Pathogen Magnaporthe oryzae Triticum

Md. Yeasinul Haque Rayhan, Md. Humayun Kabir, Md. Mahbubur Rahman, Md. Ashraful Islam, Md. Imtiaz Uddin, M Bahadur Meah


That Magnaporthe oryzae Triticum is seed-borne, it is confirmed. Random distribution of infected seeds during sowing plays a vital role in epidemic occurrence of wheat blast in the field. Once the spike is infected, local spread of wheat blast occurs by spores from the infected spike. Under Bangladesh field condition, plants with bleached spike seldom shows leaf infection. So, question arises if a bleached spike on a single plant is through systemic infection, however, it is not known. Experiments were conducted to explore the possibility of systemic infection of a wheat spike i.e., when seed is sown the Magnaporthe oryzae Triticum traverses from seed to all the way to developing spike of wheat. Seed samples of wheat variety BARI Gom23 were collected from the farmers of three upazila of blast hotspot Meherpur district. Seeds were incubated in moist blotter in room temperature (30 C ± 1). Any growth of Magnaporthe oryzae pv Triticum (MoT) seen under stereo-binocular microscope was confirmed through microscopic slide preparation. In seed samples, seed infection of MoT ranged 0-22% were grouped into four treatments (0, 1-10, 11-20 and >20%) which were later sown in pots. Seed germination ranged from 83 to 87% for the four seed categories. Seeds and plant parts were processed for DNA extraction, PCR was run with primer MoT3. For anatomical study, TSs of root, stem and rachis were made. Plants grown out of the four groups of seeds all except healthy seeds carried blast infection showing different levels of bleached spikes. Agarose (1.5%) gel electrophoresis produced monomorphic bands of 361bp in all categories of seeds and plant parts except those from healthy seeds. TSs of plant parts displayed both intra- and inter-cellular mycelium of MoT in the ground tissues and xylem bundles. The results of this study confirmed the seed infection as observed in moist blotter was of Magnaporthe oryzae pv Triticum and confirmed the transmission of pathogen from seed to plant to seed through vascular bundle. It may be concluded that MoT is both seed-borne and seed transmitted


Magnaporthe oryzae Triticum, Anatomy, Seed to plant to seed transmission

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