Publications by authors named "Hafiz Muhammad Usman Aslam"

2 Publications

  • Page 1 of 1

First report of brown leaf spot of rice caused by Bipolaris zeicola in Pakistan.

Plant Dis 2020 Aug 17. Epub 2020 Aug 17.

University of Agriculture Faisalabad, 66724, Entomology, Faisalabad, Punjab, Pakistan;

Rice (Oryza sativa L.) is one of the highly consumed cereal grain crops in Pakistan. In September 2017, leaf samples of cultivar Basmati-385 showing brown to dark brown spots (5 to 9 mm in diameter) that were oval or cylindrical in shape with a chlorotic yellow halo and grayish tan centers were collected from fields near the University of Agriculture, Faisalabad (31.43633 N 73.05981 E). Average disease incidence was 69% in six rice fields that were sampled for diseased plants with visible symptoms. To isolate the pathogen, from 20 diseased leaves, 5 mm2 segments from the margins of lesions were cut, rinsed with sterile distilled water (SDW), surface disinfected by 70% ethanol and again rinsed with SDW. The samples were dried on sterilized filter paper discs, plated on potato dextrose agar (PDA) and incubated at 27°C for 5 to 7 days. Twelve isolates were sub-cultured and single-sporing was performed to obtain pure cultures. Fungal isolates with light to dark gray in color, thick or fluffy aerial mycelium, circular and smooth margins were obtained after 7 days of incubation. Conidia were 47-83 μm × 10-17 μm (n=100), with 4 to 10 distosepta, dark or olivaceous brown, straight or moderately curved, and the cells at the ends occasionally looked paler than those in the middle. Conidiophore of the fungus were simple, smooth, cylindrical, septate, and straight to flexuous. These characteristics resembled those of Bipolaris zeicola (Stout) Shoemaker (Manamgoda et al. 2014). For molecular identification, genomic DNA (isolate SU-11) was extracted and the internal transcribed spacer (ITS) region, large subunit (LSU) of ribosomal DNA, translation elongation factor (tef), glyceraldehyde 3-phosphate dehydrogenase (gpd), and RNA polymerase II second largest subunit (rpb2) genes were amplified and sequenced by using the primers ITS1-F/ITS4-R (White et al. 1990), LROR-F/LR5-R (Schoch et al. 2012), EF1-983F/EF1-2218R (Rehner and Buckley 2005), GPD1F/GPD2R (Berbee et al. 1999), and 5F2/7CR (O'Donnell et al. 2007), respectively. BLASTn searches showed 100% homology with the LSU and rpb2 sequences of B. zeicola (GenBank Accession Nos. MH876201 and HF934842) and 98-99% similarity with ITS, tef, and gpd sequences of B. zeicola (GenBank Accession Nos. KM230398, KM093752 and KM034815). The sequences of ITS, LSU, tef, gpd, and rpb2 were deposited in GenBank with accession numbers MN871712, MN877767, MN867685, MN904511 and MT349837, respectively. To fulfill Koch's postulates, 25 greenhouse-grown rice plants (cv. Basmati-385) at 2- to 3-leaf stage were spray inoculated with a spore suspension (105 spores/ml; isolate SU-11) prepared in SDW. Plants were covered with plastic wraps to maintain humid conditions for 24 hours and incubated at 27°C for one week. Similarly, ten non-inoculated plants sprayed with SDW served as controls. After one week, observed symptoms were similar to those from natural infections and no disease symptoms were observed on the non-inoculated plants. The experiment was repeated twice and the pathogen was re-isolated from the infected leaves and characterized morphologically. Globally, B. zeicola has also been reported to cause the leaf spot of rice and maize plants (Sivanesan 1987; Kang et al. 2018). To our information, this is the first report of B. zeicola causing brown leaf spot of rice in Pakistan. The increasing risk of this fungal pathogen in the rice-growing areas of Pakistan need a rigorous exploration and outreach effort to develop effective management practices.
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http://dx.doi.org/10.1094/PDIS-04-20-0838-PDNDOI Listing
August 2020

Assessment of grain yield indices in response to drought stress in wheat ( L.).

Saudi J Biol Sci 2020 Jul 17;27(7):1818-1823. Epub 2019 Dec 17.

Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia.

Drought stress constricts crop production in the world. Increasing human population and predicted temperature increase owing to global warming will lead ruthless problems for agricultural production in near future. Hence, use of high yielding genotypes having drought tolerance and scrutinize of drought sensitive local cultivars for making them tolerant may be the proficient approaches to cope its detrimental outcomes. The current study was executed during 20015-2016 and 2016-2017 in field using randomized complete block design under factorial arrangements on 50 wheat genotypes for exploring their sensitivity and tolerance against drought. Some of the attributes of grain yield and drought tolerance indices were recorded. Grain yield showed negative correlations with tolerance index (TOL), drought index (DI) and stress susceptibility index (SSI) while positive correlation with mean productivity (MP) and geometric mean productivity (GMP) under drought condition. These findings depicted that tolerant genotypes could be chosen by high MP and GMP values and low SSI and TOL values. Based on the results, genotypes GA-02, Faisalabad-83, 9444, Sehar-06, Pirsabak-04 and Kohistan-97 were more tolerant and recognized as suitable for both normal and drought conditions. Genotypes of Chenab-00, Kohsar-95, Parwaz-94 and Kohenoor-83 confirmed more sensitive due to high grain yield loss under drought stress.
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http://dx.doi.org/10.1016/j.sjbs.2019.12.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296489PMC
July 2020