Occurrence of genetic lineages of Puccinia Striiformis in Latvia

Puccinia striiformis is a biotrophic pathogen able to cause broad scale epidemics in wheat growing regions. P. striiformis is genetically highly variable pathogen. New, aggressive genetic lineages, adapted to warm temperatures have been observed in the last decades worldwide. The study aimed to ascertain the structure of genetic lineages of P. striiformis in Latvia. Forty one wheat leaf samples with yellow rust symptoms were collected in 2017–2019. Fenotyping and genotyping methods were used for identification of genetic lineages in Global Rust Reference Center, Denmark. Assessments of leaf diseases on winter wheat differentials – ‘Ambition’, ‘Mariboss’, ‘Moro’, ‘Compair’, ‘Rendezvous’, ‘Spalding Prolific’ and local variety ’Fredis’ were made during the research. Five genetic lineages of P. striiformis – PstS4, PstS7, PstS10, PstS13 and PstS14 were found. 56% from the samples belonged to PstS14, 17.1% PstS10, 12.2% PstS4 and PstS7, 2.4% PstS13. Genetic lineages identified from Latvian wheat samples are found in the biggest cereal growing regions in Europe and are able to cause epidemics on wheat. Genetic lineages of P. striiformis from Latvian samples have not been identified before. All differential varieties were infected with P. striiformis in 2017, ‘Ambition’ and ‘Moro’ in 2018, no infection was observed on differentials in 2019 despite the presence of P. striiformis on winter wheat variety ‘Fredis’. The identification of genetic lineages of P. striiformis on wheat in Latvia is necessary to continue.

Pathogenicity of Isolates of the Rice Blast Pathogen (Pyricularia oryzae) from Indonesia

A total of 201 isolates of Pyricularia oryzae (the causal agent of rice blast) were collected from three rice ecosystems (upland, lowland, and swampy) in five regions of Indonesia (West Java, Lampung, South Sumatra, Kalimantan, and Bali). Their pathogenicities were characterized based on the patterns of reaction of 25 differential varieties (DVs) and the susceptible control Lijiangxintuanheigu (LTH), which was susceptible to all blast isolates. A high proportion of isolates (>80.0%) were virulent to DVs for resistance genes Pib, Pit, Pia, Pik-s, and Pi12(t), and a low proportion of isolates (<12.9%) were virulent to DVs for Pik-m, Pi1, Pik-h, Pik, Pik-p, and Pi7(t). Virulence to the other DVs for Pish, Pii, Pi3, Pi5(t), Pi9(t), Piz, Piz-5, Piz-t, Pita-2 (two lines), Pita (two lines), Pi19(t), and Pi20(t) showed intermediate frequencies from 20.0% to 80.0%. These isolates were classified into three cluster groups Ia, Ib, and II, and the frequencies of cluster groups varied among the three ecosystems and the five regions. The frequencies of cluster groups varied among the different ecosystems and regions, and races varied according to the ecosystems. A total of 27 standard differential blast isolates (SDBLs) were selected from the 201 isolates collected. The set of 25 DVs and these 27 SDBIs will be used as a new differential system for analysis of the pathogenicity of blast isolates and analysis of resistance genes in rice cultivars, which will contribute to building up a durable protection system against blast disease in Indonesia.

Diversity and Distribution of Rice Blast (Pyricularia oryzae Cavara) Races in Vietnam

A total of 239 isolates of blast (Pyricularia oryzae Cavara) collected from northern and central Vietnam showed a wide variation in pathogenicity based on the reaction patterns to 25 differential varieties (DVs) harboring 23 resistance genes and susceptible cultivar Lijiangxintuanheigu (LTH). The frequencies of isolates virulent toward DVs for Pish, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi9(t), Piz-5, Pita-2, and Pita were low, but they were high for DVs for Pib, Pit, Pia, Pii, Pi3, Pi5(t), Pik-s, Piz, Piz-t, Pi12(t), Pi19(t), and Pi20(t). Isolates were classified into three cluster groups Ia, Ib, and II based on reaction patterns to DVs and LTH. The frequencies of isolates virulent toward 11 DVs for Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi9(t), Piz, Piz-5, Pita-2, and Pita in cluster II and DV for Piz-t were higher and lower than those of Ia and Ib, respectively. The frequencies to DVs for Pii, Pi3, Pi5(t), and Piz-t were different between clusters Ia and Ib. Clusters Ia and Ib were distributed with similar frequencies in the northeast, north central, and south central coast regions, but the frequencies among three cluster groups in the Red River Delta and northwest regions were different. This means that the blast races in these two regions were different from the others. Overall, the blast isolates were categorized into 153 races. Among them, 26 were selected as a set of standard differential blast isolates for characterizing 23 resistance genes and developing a differential system in Vietnam.

Genetic Variation of Rice Blast (Pyricularia oryzae) Isolates in Laos

The pathogenicity of 192 blast isolates collected from regions across the whole of Laos from 2007 to 2009 showed a wide variation in terms of the frequencies of virulence toward differential varieties (DVs) and the susceptible control cultivar Lijiangxintuanheigu. High frequencies of virulence (>50%) were found in the reactions of DVs for Pit, Pia, Pi3, Pi5(t), Pik-s, Piz-t, Pi19(t), and Pi20(t); intermediate values (from 10 to 50%) were found in DVs for Pib, Pii, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Piz-5, Pita (two lines), Pita-2 (two lines), and Pi12(t); and low frequencies (<10%) were found in DVs for Pish, Piz, and Pi9(t). The blast isolates were classified into three cluster groups: Ia and Ib (low virulence) and II (high virulence), based on the patterns of reaction to them. The blast isolates in cluster group Ia were dominant in rainfed lowland areas, those in Ib were dominant in irrigated lowland areas, and those in II were dominant in upland areas. Cluster groups Ia, Ib, and II were dominant in the Southern, Central, and Northern regions, respectively. Blast races in Laos were distributed according to ecosystems for rice cultivation and geographical regions from south to north with different virulence. These isolates were categorized into 156 races, and the numbers of blast isolates were few in each race. A total of 15 representative isolates were selected from among them as standard differential blast isolates, to develop a differential system.

Pathogenicities of Rice Blast (Pyricularia oryzae Cavara) Isolates From Kenya

A total of 99 isolates of rice blast (Pyricularia oryzae Cavara) were collected from 2010 to 2015 from four regions in Kenya: Kirinyaga County and Embu County, Kisumu County, Tana River County, and Mombasa County. The pathogenicities of these isolates were clarified based on the reaction patterns of Lijiangxintuanheigu and differential varieties (DVs) targeting 23 resistance genes. The frequency of virulent isolates was high for DVs for Pib, Pia, Pii, Pi3, Pi5(t), Pik-s, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi19(t), and Pi20(t); low for DVs for Pish, Pi9(t), Piz-5, and Piz-t; and intermediate for the remaining DVs for Pit, Piz, Pita-2, Pita, and Pi12(t). These blast isolates were classified into three cluster groups: Ia, Ib, and II. The frequencies of virulent isolates to DVs for Pit, Pii, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Piz, and Pi12(t) differed markedly between clusters I and II, and those of DVs for Pib, Pit, Pia, Pi3, Pita-2, Pita, and Pi20(t) differed between Ia and Ib. The frequencies of cluster groups in the four geographical regions were different. A total of 62 races were found, with 19 blast isolates categorized into one race (U63-i7-k177-z00-ta003), whereas the other races included only some isolates in each.

Identifikasi Gen Ketahanan terhadap (Xanthomonasoryzae pv. Oryzae), penyebab Penyakit Hawar Daun Bakteri padaPlasma Nutfah Padi Lokal Sulawesi Selatan

One of limiting factor in rice production especially in South Sulawesi was the bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. Oryzae (Xoo). In South Sulawesi, it had been reported that 58% Xoo of race III were dominant in Bone, Sopeng, Wajo, Sidrap, Barru, Pangkep. Meanwhile, 23% of race IV and 19% of race VIII were dominant in Maros. The effort that considered the most effective to control BLB disease was the planting of resistant variety. The rice variety assembling by using the resistance genes from various cultivars gave the opportunity to produce the BLB-resistant variety. This research aimed to identify BLB disease-resistant gene on local rice germplasm from South Sulawesi based on the association analysis between phenotype resistance and genotype marker of resistance gene to Xoo. The analysis of phenotype resistance testing was done by using three races of BLB, races III, IV, and VIII with IRBB differential varieties. Meanwhile, the genotype analysis was done by using the molecular marker linked to BLB-resistant trait. For linkage analysis between the both of data was done the association analysis between the both of data with Cladogram analysis on Tassel Program. The resistance testing result showed almost all of the local rice in South Sulawesi was resistant to race III, 6 accessions were resistant to race IV and 6 accessions were resistant to race VIII. The association analysis result was known the markers that significant to mark the resistance trait from every race. Marker Xa26-SN2 was significant to mark the resistance trait to race III, the marker Xa1-SN15, Xa4-SN44, Xa13-SN51, and Xa21-SN6 were significant to race IV, marker Xa7-SN57 and RM20589 were significant to race VIII. These markers pottentially as a MAS (Marker Assisted Selection) markers that could be used to aasist the selection of local rice germplasm from South Sulawesi.

Evaluation of neck blast resistance and agronomical performances on double haploid rice population in greenhouse and endemic field

Windarsih G, Utami DW. 2017. Evaluation of neck blast resistance and agronomical performances on double haploid rice population in greenhouse and endemic field. Nusantara Bioscience 9: 371-377. Blast disease caused by fungal Pyricularia grisea Sacc. is one of the most destructive diseases of rice in the world. The development of blast-resistant rice varieties will be essential to control this disease. This research aimed (i) to compare the resistance response to neck-blast among DH lines from double cross IR54/Parekaligolara//Bio110/Markuti and the differential varieties against three selected Indonesian blast races in greenhouse, (ii) to identify the gene(s) that caused the resistance to neck-blast based on the association between the resistance response and the genotype evaluation using molecular markers linked to Pi1, Pi33, Pib, Pir4 and Pir7 genes, and (iii) to evaluate the resistance response to leaf and neck blast on DH lines in endemic field (Sukabumi) and the agronomical performance of selected DH lines in optimum field in Ciasem of Subang, West Java, Indonesia during December 2013 to March 2014. Eleven double haploid lines from double-crossing IR54/Parekaligolara//Bio110/Markuti, the differential varieties as resistant control and the US2 variety for susceptible control were observed for neck-blast resistance response to three blast races in greenhouse and endemic field (Sukabumi), while the agronomical performances were observed in field of Ciasem-Subang. The results based on the genotyping evaluation, leaf and neck blast resistance, either in greenhouse and endemic location, and the agronomical performance in field showed that 5 selected double haploid lines had leaf and neck blast resistance and good performance on field trial. Thus they are promising for use either for further testing forwarding into releasing variety or used as donor for further blast resistant breeding activities.