Oryzae Pathotype Research Articles

Effects of plant extracts on controlling wheat blast disease caused by Magnaporthe oryzae Pathotype triticum in Bangladesh

The present research work was conducted to evaluate the efficacy of twelve plant extracts viz. Neem (Azadirachta indica), Bishkatali(Polygonum hydropiper), Nishinda (Vitex negundu), Allamonda (Allamanda cathertica), Acasia (Acacia auriculiformis), Tulsi (Ocientific tenuiflorum), Mehendi (Lmetawsonia alba), Datura (Datura metel), Bishkochu (Alocasia fornicate), Black cumin (Nigella sativa), Garlic (Allium sativum), Mehogoni (Swietenia macrophylla) @ 1:10 along with two fungicides Provax and Nativo @ 0.2% as check against Magnaporthe oryzae Pathotype triticum which is responsible for wheat blast disease at Department of Plant Pathology, Bangladesh Agricultural University and Plant Pathology Division, Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh-2202. This experiment was conducted in two phases viz. laboratory and pot experiment. In the laboratory experiment, the efficacies of plant extracts were evaluated by the measurement of percent inhibition of radial mycelial growth of M. oryzae Pathptype triticum. The highest percentage of mycelial inhibition (93.75%) was recorded in case of four plant extracts namely Tulsi, Mehendi, Datura and Garlic followed by Black cumin seed extracts (90%) at 10 days after inoculation, where as Allamonda leaf extract showed lowest percentage of mycelial growth inhibition (7.5%). On the basis of in vitro test five plant extracts were selected to conduct pot experiment to evaluate the disease incidence and severity, and some yield contributing parameters in treated and control plants. Minimum percentage of disease incidence and severity were recorded in case of Garlic clove extract ( 16.28 and 3.5) treated plants and the Mehendi leaf extract treated plants showed highest % of disease incidence and severity (66.0% and 68.0%). Garlic clove extracts also showed best performance for yield contributing parameters namely ear length (9.20 cm), number of ear/pot (13.25), number of healthy ear/pot (13.0), number of total and healthy spikelets/ear (34.20 and 33.40),number of total and healthy grains/ear (23.00 and 21.80) and weight of 1000 total and healthy grains/pot (56 and 52 gm) followed by Black cumin, whereas Mehendi leaf extract treated plants showed lowest value for all the yield contributing parameters among the plant extracts used in this experiment. Both in in vito and pot experiment Garlic extract showed best performance and it might be used for the eco-friendly management of blast disease and increase the yield of wheat.

Identifikasi Patotipe Xanthomonas oryzae pv. oryzae dari Tanaman Padi di Sulawesi Selatan

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight (BLB), one of important constraint in rice production. The pathogen is known to have many pathotypes which caused difficulties in disease control. This research was conducted to determine the distribution of X. oryzae pv. oryzae ’s pathotypes in seven districts in South Sulawesi. Grouping of pathotypes was performed according to Kozaka method, i.e. based on the response of differential rice varieties. Infection of X. oryzae pv. oryzae was confirmed by PCR using specific primers XOR-R2/XOR-F. Out of 36 isolates, 29 isolates were identified as X. oryzae pv. oryzae which belong to pathotype III (6 isolates), pathotype IV (21 isolates), and pathotype XII (2 isolates). This result indicated that X. oryzae pv. oryzae pathotype IV was distributed widely in South Sulawesi.

Komposisi Dan Dominasi Patotipe Xanthomonas oryzae pv. oryzae Penyebab Hawar Daun Bakteri Pada Tanaman Padi Dengan Pola Tanam Tidak Serempak

Research to determine the dynamics of composition and domination of Xanthomonas oryzae pv. oryzae (Xoo) pathotype, the bacterial leaf blight (BLB) pathogen of rice in areas with different planting time was carried out in Klaten Regency, Central Java Province, in the Wet Season (WS) 2014/2015 and Dry Season (DS) 2015. The research consisted three steps, namely: observation and sampling of plants in the field, isolation the pathogen in the laboratory, and pathotype identification in the greenhouse. Observations and samplings of diseased plants in each growing season were conducted at planting time, i.e.: early planting (I), mid planting (II), and late planting (III). The results showed that Xoo pathotype composition in WS 2014/2015 and DS 2015 were pathotype III, IV, and VIII with varying dominance between the planting period in the season, as well as between seasons, and between observation location. The composition of Xoo pathotype was dominated by pathotype IV in the early and mid planting periods of WS 2014/2015, whereas at the end of planting period was dominated by pathotype III. Xoo composition in early, mid, and late planting periods of DS 2015 was dominated by pathotype III. Based on these results is suggested to control BLB in non synchronous cropping pattern at early and mid planting period of wet season by planting resistant varieties to Xoo pathotype IV, while in areas the late planting period, it is suggested to planting resistant varieties to Xoo pathotype III and VIII. The BLB control in areas with early, mid, and late planting periods of dry season is suggested to planting resistant varieties to Xoo pathotype III or VIII.

First Report of Wheat Blast Caused by Magnaporthe oryzae Pathotype triticum in Bangladesh

First Report of Wheat Blast Caused by <i>Magnaporthe oryzae</i> Pathotype <i>triticum</i> in Bangladesh

Ketahanan Berbagai Kultivar Padi Lokal terhadap Penyakit Hawar Daun Bakteri

Bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae is an important rice disease in Indonesia, including in South East Sulawesi. The use of resistant varieties is one of the effective and environmentally friendly control strategies to suppress the disease. This study aimed to determine the level of resistance of some local rice varieties of South and Southeast Sulawesi against Xanthomonas oryzae pv. oryzae pathotypes IV, VIII and X. The study was conducted in a screen house involving 3 bacterial pathotypes and 11 local rice cultivars. Shearing method was used for inoculation of bacteria to leaf on vegetative and generative phases. Disease incidences were measured 3 weeks after inoculation, and the data was further used to determine the level of resistance of the tested rice cultivars. The results showed that incubation period of the disease was longer on Kelaca cultivar compared to other cultivars. On vegetative phase, this cultivar showed moderate resistant to pathotypes IV and X, and highly resistant to patotype VIII, whereas on the generative phase it showed moderate resistant to pathotypes IV and VII, and highly resistant to pathotype X. Therefore, Kelaca cultivar can be recommended for endemic areas of leaf blight in South and Southeast Sulawesi

Over-Expression of the Pikh Gene with a CaMV 35S Promoter Leads to Improved Blast Disease (Magnaporthe oryzae) Tolerance in Rice.

Magnaporthe oryzae is a rice blast fungus and plant pathogen that causes a serious rice disease and, therefore, poses a threat to the world's second most important food security crop. Plant transformation technology has become an adaptable system for cultivar improvement and to functionally analyze genes in plants. The objective of this study was to determine the effects (through over-expressing and using the CaMV 35S promoter) of Pikh on MR219 resistance because it is a rice variety that is susceptible to the blast fungus pathotype P7.2. Thus, a full DNA and coding DNA sequence (CDS) of the Pikh gene, 3172 bp, and 1206 bp in length, were obtained through amplifying the gDNA and cDNA template from a PH9-resistant rice variety using a specific primer. Agrobacterium-mediated transformation technology was also used to introduce the Pikh gene into the MR219 callus. Subsequently, transgenic plants were evaluated from the DNA to protein stages using polymerase chain reaction (PCR), semi-quantitative RT-PCR, real-time quantitative PCR and high performance liquid chromatography (HPLC). Transgenic plants were also compared with a control using a real-time quantification technique (to quantify the pathogen population), and transgenic and control plants were challenged with the local most virulent M. oryzae pathotype, P7.2. Based on the results, the Pikh gene encodes a hydrophilic protein with 18 sheets, 4 helixes, and 21 coils. This protein contains 401 amino acids, among which the amino acid sequence from 1 to 376 is a non-cytoplasmic region, that from 377 to 397 is a transmembrane region, and that from 398 to 401 is a cytoplasmic region with no identified disordered regions. The Pikh gene was up-regulated in the transgenic plants compared with the control plants. The quantity of the amino acid leucine in the transgenic rice plants increased significantly from 17.131 in the wild-type to 47.865 mg g−1 in transgenic plants. The M. oryzae population was constant at 31, 48, and 72 h after inoculation in transgenic plants, while it was increased in the inoculated control plants. This study successfully clarified that over-expression of the Pikh gene in transgenic plants can improve their blast resistance against the M. oryzae pathotype P7.2.

EKSPLORASI DAN UJI SENYAWA BIOAKTIF BAKTERI AGENSIA HAYATI UNTUK PENGENDALIAN PENYAKIT KRESEK PADA PADI

Exploration of bacterial biocontrol agent and its potential bioactive compound to control rice bacterial leaf blight. The research aims were to obtain bacterial isolates which were potential as biological control agent of X. oryzae pv. oryzae, the causal agent of rice bacterial blight and to assess the effectiveness of their bioactive compounds, and to identify of the potential isolates. The research steps included bacterial isolation, screening based on antibiosis activity and pathogenicity test, characterization based on chitinolytic enzyme production, siderophores, and phosphate dissolution test, effectiveness test of bioactive compounds and molecular identification of potential isolates. Out of 156 bacterial isolates from rice crop tested, 11 isolates showed to be non plant pathogenic and to have activity as biological agents against X. oryzae pv. oryzae pathotype III, IV and VIII. Further characterization of 11 isolates resulted in 2 isolates that showrd ability to produce chitinase (isolates T5-1118 and R7-1018), phosphatase (isolates T5-1105 and T6-1109), and siderophores (isolates T5-1118 and T6- 1109). The test of bioactive compound effectiveness of 4 isolates to the growth of X. oryzae pv. oryzae showed thatT5-1118, T5-1105, T6-1109 and R7-1018 have ability to inhibit X. oryzae pv. oryzae at 48 hours after inoculation of 66,61%, 62,4%, 23,97% and 12,40%, respectively. Identification of 4 bacterial biocontrol isolates with partial sequencing of 16S rRNA gene showed that those bacteria are close to Bacillus nealsonii strain F22 (R7-1018), Chromobacterium sp. MWU328 (T5-1118), Streptomyces sp. Antag 1 (T5-1105) and Kitasatospora nipponensis strains H2-4 (T6-1109).

Komposisi dan Sebaran Patotipe Xanthomonas oryzae pv. oryzae, Penyakit pada Padi di Nusa Tenggara Barat

&lt;p&gt;A study was carried out to identify the composition and distribution of Xanthomonas oryzae pv. oryzae (Xoo) pathotypes on rice crop in West Nusa Tenggara, during the 2012 planting season. Three activities were conducted, namely collection of rice leaf samples from the fields, isolation of Xoo from the leaf samples at the laboratory, and testing pathotypes of Xoo at the screen house. Rice leaves showing typical bacterial leaf blight (BLB) symptom were collected from various farmers’ fields. The samples were detached and put into paper envelopes, and were taken to the laboratory for isolation of Xoo, at the Laboratory of Pythopathology of Indonesian Center for Rice Research (ICRR), Sukamandi. Pathotype testing was done in the ICRR screen house by inoculating the leaves of five differential rice varieties using inocula of the Xoo isolates. Resistance of the rice differential varieties was determined based on the BLB disease severity. Inoculated plant with disease severity ≤11% was considered resistant (R) and disease severity &amp;gt;11% was susceptible (S). From the 240 samples of rice leaf infected with BLB collected from West Nusa Tenggara, 232 Xoo isolates were obtained. The Xoo pathotype identification showed that pathotype IV was the most dominant in West Nusa Tenggara during the 2012 planting season, numbering 118 isolates or 51.0% out of the total isolates, followed by pathotype VIII (67 isolates or 29.0%), and pathotype III (47 isolates or 20.0%).&lt;/p&gt;

Identification of quantitative trait loci for blast resistance in BC2F3 and BC2F5 advanced backcross families of rice

Advanced backcross families derived from Oryza sativa cv MR219/O. rufipogon IRGC105491 were utilized for identification of quantitative trait loci (QTL) for blast resistance using simple sequence repeat markers. Two hundred and sixty-one BC(2)F(3) families were used to construct a linkage map, using 87 markers, which covered 2375.2 cM of 12 rice chromosomes, with a mean density of 27.3 cM. The families were evaluated in a greenhouse for resistance to blast disease caused by pathotypes P7.2 and P5.0 of Magnaporthe oryzae. Five QTLs (qBL5.1, qBL5.2, qBL6.1, qBL8.1, and qBL10.1) for pathotype P5.0 and four QTLs (qBL5.3, qBL5.4, qBL7.1, and qBL8.2) for pathotype P7.2 were identified using the BC(2)F(3) families. Another linkage map was also constructed based on 31 BC(2)F(5) families, using 63 SSR markers, which covered 474.9 cM of 9 rice chromosomes, with a mean density of 8.01 cM. Five suggestive QTLs (qBL11.2, qBL11.3, qBL12.1, qBL12.2, qBL12.3) and one putative QTL (qBL2.1) were identified for pathotype P7.2. Also, seven suggestive QTLs (qBL1.1, qBL2.2, qBL4.1, qBL4.2, qBL5.3, qBL8.3, and qBL11.1) were detected for pathotype P5.0. We conclude that there is a non-race-specific resistance spectrum of O. rufipogon against M. oryzae pathotypes.

Analysis of simple sequence repeat markers linked with blast disease resistance genes in a segregating population of rice (Oryza sativa)

Among 120 simple sequence repeat (SSR) markers, 23 polymorphic markers were used to identify the segregation ratio in 320 individuals of an F(2) rice population derived from Pongsu Seribu 2, a resistant variety, and Mahsuri, a susceptible rice cultivar. For phenotypic study, the most virulent blast (Magnaporthe oryzae) pathotype, P7.2, was used in screening of F(2) population in order to understand the inheritance of blast resistance as well as linkage with SSR markers. Only 11 markers showed a good fit to the expected segregation ratio (1:2:1) for the single gene model (d.f. = 1.0, P < 0.05) in chi-square (χ(2)) analyses. In the phenotypic data analysis, the F(2) population segregated in a 3:1 (R:S) ratio for resistant and susceptible plants, respectively. Therefore, resistance to blast pathotype P7.2 in Pongsu Seribu 2 is most likely controlled by a single nuclear gene. The plants from F(2) lines that showed resistance to blast pathotype P7.2 were linked to six alleles of SSR markers, RM168 (116 bp), RM8225 (221 bp), RM1233 (175 bp), RM6836 (240 bp), RM5961 (129 bp), and RM413 (79 bp). These diagnostic markers could be used in marker assisted selection programs to develop a durable blast resistant variety.

Hot spots for diversity of Magnaporthe oryzae physiological races in irrigated rice fields in Brazil

The objective of this work was to evaluate the Magnaporthe oryzae pathotype diversity in new commercial irrigated rice fields in the Araguaia River Valley, state of Tocantins, Brazil. The causal agent of rice blast has heavily affected rice production in the region. Despite the efforts of breeding programs, blast resistance breakdown has been recorded shortly after the release of new resistant cultivars developed for the region. Among the causes of resistance breakage is the capacity of the fungus to rapidly develop new pathotypes. A sample of 479 M. oryzae monosporic isolates was obtained and tested using the international rice blast differential set. Isolate collections were made in small areas designed as trap nurseries and in scattered sites in their vicinity. Analysis of 250 M. oryzae isolates from three trap nurseries indicated the presence of 45 international M. oryzae races belonging to seven pathotype groups (IA-IG). In the isolates tested, 61 M. oryzae pathotypes belonging to all but the IH group were detected. The new areas of irrigated rice in the Araguaia River Valley have the highest diversity of M. oryzae pathotypes reported so far in Brazil.