Magnaporthe oryzae, causative agent of the rice blast disease, is a major concern for the loss in yield of rice crop across the globe. It is known for its characteristic melanised dome-shaped appre...

https://www.tandfonline.com/doi/pdf/10.1080/21501203.2020.1868594

Molecular virulence determinants of Magnaporthe oryzae: disease pathogenesis and recent interventions for disease management in rice plant

Rice blast disease is one of the major constraints to rice production, threatening food security globally. Rice grain production losses due to the disease leads economic losses to the farmers, and to an increase in global rice price as a result of the supply that is far below the consumer demand. The losses from the disease annually was estimated to feed over 60 million individual. The disease has been studied comprehensively by researchers due to the importance attached to rice and its vast spread and destructiveness across the globe. A good understanding of the pathogen causing the disease, its life cycle and development, epidemiology, symptoms, management strategy will offer a good insight into the disease incidence and give an appropriate and effective decision-making in its management. Different control measures have been adopted managing the disease, including the use of resistant varieties. Integrated disease management strategies coupled with good agronomy practices are required for successful control of rice blast for food security. This review, therefore, examined the fundamentals of rice blast disease (Magnaporthe oryzae) and offered strategies to minimize the disease activities to ensure proper production and increase the supply of rice grains.

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Rice Blast Disease (Magnaporthe oryzae): A Menace to Rice Production and Humanity

Magnaporthe oryzae (M. oryzae) is a typical cause of rice blast in agricultural production. Isobavachalcone (IBC), an active ingredient of Psoralea corylifolia L. extract, is an effective fungicide against rice blast. To determine the mechanism of IBC against M. oryzae, the effect of IBC on the metabolic pathway of M. oryzae was explored by transcriptome profiling. In M. oryzae, the expression of pyruvate dehydrogenase E1 (PDHE1), part of the tricarboxylic acid (TCA cycle), was significantly decreased in response to treatment with IBC, which was verified by qPCR and testing of enzyme activity. To further elucidate the interactions between IBC and PDHE1, the 3D structure model of the PDHE1 from M. oryzae was established based on homology modeling. The model was utilized to analyze the molecular interactions through molecular docking and molecular dynamics simulation, revealing that IBC has π-π stacking interactions with residue TYR139 and undergoes hydrogen bonding with residue ASP217 of PDHE1. Additionally, the nonpolar residues PHE111, MET174, ILE 187, VAL188, and MET250 form strong hydrophobic interactions with IBC. The above results reveal that PDHE1 is a potential target for antifungal agents, which will be of great significance for guiding the design of new fungicides. This research clarified the mechanism of IBC against M. oryzae at the molecular level, which will underpin further studies of the inhibitory mechanism of flavonoids and the discovery of new targets. It also provides theoretical guidance for the field application of IBC.

https://www.mdpi.com/1422-0067/22/10/5163/pdf

Identification of Pyruvate Dehydrogenase E1 as a Potential Target against Magnaporthe oryzae through Experimental and Theoretical Investigation

Gamma-irradiated fenugreek extracts mediates resistance to rice blast disease through modulating histochemical and biochemical changes.

Rice blast disease is one of the major bottlenecks of rice production in the world including Bangladesh. To develop blast resistant lines, a cross was made between a high yielding but blast susceptible variety MR263 and a blast resistant variety Pongsu seribu 2. Marker-assisted backcross breeding was followed to develop F1, BC1F1, BC2F1, BC2F2, BC2F3, BC2F4 and BC2F5 population. DNA markers i.e., RM206, RM1359 and RM8225 closely linked to Pb1, pi21 and Piz blast resistant genes, respectively and marker RM276 linked to panicle blast resistant QTL (qPbj-6.1) were used in foreground selection. Calculated chi-square (χ2) value of phenotypic and genotypic segregation data of BC2F1 population followed goodness of fit to the expected ratio (1:1) (phenotypic data χ2 = 1.08, p = 0.701; genotypic data χ2 = range from 0.33 to 3.00, p = 0.08-0.56) and it indicates that the inheritance pattern of blast resistance was followed by a single gene model. Eighty-nine advanced lines of BC2F5 population were developed and out of them, 58 lines contained Piz, Pb1, pi21, and qPbj-6.1 while 31 lines contained Piz, Pb1, and QTL qPbj-6.1. Marker-trait association analysis revealed that molecular markers i.e., RM206, RM276, and RM8225 were tightly linked with blast resistance, and each marker was explained by 33.33% phenotypic variation (resistance reaction). Morphological and pathogenicity performance of advanced lines was better compared to the recurrent parent. Developed blast resistance advanced lines could be used as donors or blast resistant variety for the management of devastating rice blast disease.The online version contains supplementary material available at 10.1007/s12298-022-01141-3. 

Linkage of SSR markers with rice blast resistance and development of partial resistant advanced lines of rice (Oryza sativa) through marker-assisted selection

Rice blast caused by Magnaporthe grisea is the major damaging disease in nearly all rice growing nations. Economically relevance with 60 percent of total population of world depending on rice as the main source of calories, may have destructive effects of the disease, however, this pathogen has developed into a pioneering model system for researching host-pathogen interactions. The disease outbreak depends on the weather and climatic conditions of the various regions. The disease's occurrence and symptoms vary from country to country. Susceptible cultivars cause huge rice production loss in yield. The principal cause of resistance breakdown in rice against rice blast disease is pathogenic variability. During sexual hybridization, pathogenic changes may provide evidence of pathogenic variation found at the asexual stage of the fungus. The virulent pathotypes cause severe disease incidence. Only through pathogenicity research the pathotypes can be determined using a collection of different rice varieties that are usually different carrying various resistance genes. Rice breeders now have a number of resistant genes however, most of the breeding programs emphasized upon monogenic resistance. Genetic heterogeneity of M. grisea should be taken into account when screening blast resistant rice genotypes through morphological Review Article Shahriar et al.; ARRB, 35(1): 50-64, 2020; Article no.ARRB.55041 51 analysis, pathogenicity and molecular characterization. Knowledge on the virulence of the rice blast and host resistant is essential for managing the disease. Cultivation of resistant varieties with chemical control is highly effective against blast pathogens.

https://journalarrb.com/index.php/ARRB/article/download/30180/56649

Review: Rice Blast Disease

The study was carried out to find out the effect of zinc (Zn) and boron (B) on growth and yield of okra (BARI Dherosh 1). The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. The treatments of the experiment were, T0 (without Zn or B), T1 (20 kg Zn ha -1 ), T2 (30 kg Zn ha -1 ), T3 (10 kg B ha -1 ), T4 (20 kg B ha -1 ), T5 (20 kg Zn ha -1 + 10 kg B ha -1 ), T6 (20 kg Zn ha -1 + 20 kg B ha -1 ), T7 (30 kg Zn ha -1 + 10 kg B ha -1 ) and T8 (30 kg Zn ha -1 + 20 kg B ha -1 ) were undertaken to evaluate the best results of the study. The highest plant height was found in T8 (30 kg Zn ha -1 + 20 kg B ha -1 ) but the highest number of leaves plant -1 was recorded from T7 (30 kg Zn ha -1 + 10 kg B ha -1 ). On the other hand, the maximum leaf area index, SPAD value, mean fruit weight, fruit length, fruit diameter, fruit dry matter (%), number of fruits plant -1 , fresh fruit weight plant -1 , fruit yield plot -1 and fruit yield ha -1 were found in T7 (30 kg Zn ha -1 + 10 kg B ha -1 ), while the control (T0) showed lowest performance for the respected parameters. It is strongly concluded that 30 kg Zn ha -1 with 10 kg B ha -1 combination may be helpful for okra cultivation in the field level to increase okra production. Original Research Article Jahan et al.; AJAAR, 12(1): 41-47, 2020; Article no.AJAAR.54008 42

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Effect of Zinc and Boron on Growth and Yield of Okra (Abelmoschus esculentus L.)

A field experiment was conducted to evaluate the effect of light reflecting colored mulches and only one time spraying with selected insecticides to control the insect vector of Okra Yellow Vein Mosaic Virus (OYVMV) whitefly (Bemisia tabaci) at the central farm of Sher-e-Bangla Agricultural University, Dhaka-1207. The experiment was carried out in three blocks layouted with RCBD comprising eight treatments viz. T0 (control/no spray), T1 (1 time spray with imitaf), T2 (1 time spray with protect), T3 (1 time spray with tiddo plus), T4 (1 time spray with terbine), T5 (light reflecting silver color mulch), T6 (light reflecting red color mulch) and T7 (light reflecting black color mulch) with three replications. The mulches were used before sowing and insecticides were sprayed at 30 DAS. It was observed that among the light reflecting colored mulches, the lowest disease incidence (11.48%) was recorded in the plots which mulched with red color mulch (T6). Among the insecticides, the lowest disease incidence (30.17%) was recorded in plots that was sprayed with terbine (one time). Yield and yield contributing characters, morphological and physiological features of okra plant that changes due to disease infection which cause damages in okra production and reduce the fruit quality as well as market value was also the part of this study. Yield and yield contributing characters showed significant variance among the selected treatments. In the relationship study, it was noticed that the yield and plant height was showed negative relationship with disease incidence. However, considering all measuring parameters, spraying with terbine (one time) and used red color mulch may be recommended as good management approaches that will give higher okra production and lower disease incidence of Okra Yellow Vein Mosaic Virus (OYVMV).

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Management of Okra Yellow Vein Mosaic Virus (OYVMV) Through Selected Insecticides and Light Reflecting Colored Mulches

/pdf/performance-of-selected-phytochemicals-and-botanical-2sy6f1yqc4.pdf

Md. Belal Hossain

Papers

Review: Rice Blast Disease

Effect of Zinc and Boron on Growth and Yield of Okra (Abelmoschus esculentus L.)

Management of Okra Yellow Vein Mosaic Virus (OYVMV) Through Selected Insecticides and Light Reflecting Colored Mulches

Performance of Selected Phytochemicals and Botanical Nutrient on Physiological Features of Okra Varieties against Yellow Vein Clearing Mosaic Virus

Screening of Hybrid and Inbreed Rice Varieties against Tungro Disease Inoculated with Viruliferous Green Leaf Hopper (Nephotettix virescens)