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Hayashi Y.,Hokkaido University | Kozawa T.,Hokkaido Research Organization Tokachi Agricultural Experiment Station | Aiuchi D.,Obihiro University of Agriculture and Veterinary Medicine | Koike M.,Obihiro University of Agriculture and Veterinary Medicine | And 2 more authors.
European Journal of Plant Pathology | Year: 2014

Microdochium majus and Microdochium nivale are two of fungal pathogens that cause Fusarium head blight (FHB) in wheat, and have also caused pink snow mold in eastern Hokkaido, Japan. With the aim of assessing levels of genetic variation and population structure, 172 isolates of these Microdochium species obtained from five populations of infected wheat seeds were first classified into each species using polymerase chain reaction (PCR) amplification with specific primers. In total 165 (95.9 % of all isolates) and seven isolates (six of Tokachi populations and one of Abashiri populations) were identified as M. majus and M. nivale, respectively, indicating that M. majus was predominant and the main causal pathogen of FHB in this area. Inter-simple sequence repeat (ISSR) analysis showed that the total genetic diversity was 0.023 when estimated by Nei’s gene diversity index within the five populations dominated by M. majus. An AMOVA analysis also showed that 86.74 % of the total genetic variation was within populations and 13.26 % among populations. These results indicated that little genetic differentiation occurred among the five populations of M. majus. Based on the unweighted pair group method of cluster analysis using the ISSR data, all isolates were identified as one of eight haplotypes in M. majus or six haplotypes in M. nivale, allowing the construction of a dendrogram with two clades corresponding to each species. There was no correlation between the clustering of isolates and their geographic distribution on the tree. These findings show that migration is likely playing an important role in the population biology of M. majus, providing some support for the prediction of epidemics of fungicide resistant strains within populations of the FHB pathogen. © 2014, Koninklijke Nederlandse Planteziektenkundige Vereniging.


Senda M.,Hirosaki University | Nishimura S.,Hirosaki University | Kasai A.,Hirosaki University | Yumoto S.,Akita | And 4 more authors.
Breeding Science | Year: 2013

In soybean, the I gene inhibits pigmentation over the entire seed coat, resulting in yellow seeds. It is thought that this suppression of seed coat pigmentation is due to naturally occurring RNA silencing of chalcone synthase genes (CHS silencing). Fully pigmented seeds can be found among harvested yellow seeds at a very low percentage. These seed coat pigmented (scp) mutants are generated from yellow soybeans by spontaneous recessive mutation of the I gene. A candidate for the I gene, GmIRCHS, contains a perfect inverted repeat (IR) of a CHS pseudogene (pseudoCHS3) and transcripts of GmIRCHS form a double-stranded CHS RNA that potentially triggers CHS silencing. One CHS gene, ICHS1, is located 680 bp downstream of GmIRCHS. Here, the GmIRCHS-ICHS1 cluster was compared in scp mutants of various origins. In these mutants, sequence divergence in the cluster resulted in complete or partial loss of GmIRCHS in at least the pseudoCHS3 region. This result is consistent with the notion that the IR of pseudoCHS3 is sufficient to induce CHS silencing, and further supports that GmIRCHS is the I gene. ©2013 by JAPANESE SOCIETY OF BREEDING.


Hayashi Y.,Obihiro University of Agriculture and Veterinary Medicine | Kozawa T.,Hokkaido Research Organization Tokachi Agricultural Experiment Station | Aiuchi D.,Obihiro University of Agriculture and Veterinary Medicine | Tani M.,Obihiro University of Agriculture and Veterinary Medicine | Koike M.,Obihiro University of Agriculture and Veterinary Medicine
European Journal of Plant Pathology | Year: 2014

Winter wheat scab in Hokkaido, Japan is caused predominantly by Gibberella zeae and Microdochium nivale and can result in significant yield losses. A selective medium for isolation of G. zeae was previously developed, but not for M. nivale. The purpose of this study therefore was to develop a selective medium for isolation of airborne spores of M. nivale. Based on the basic composition of Komada's Fusarium-selective medium, carbon and nitrogen sources and the most suitable vitamin B component for the basal composition were examined. Hyphal growth of M. nivale was promoted when galactose was replaced with lactose and combined with L-asparagine, while aerial hyphal formation increased with thiamine hydrochloride as the vitamin B source. In antimicrobial composition, colony formation of other filamentous fungi was greatly inhibited by spiroxamine. Thiophanate methyl, to which M. nivale shows resistance, selectively inhibited the growth of Fusarium spp. only. Spore trapping using the selective medium was subsequently performed in a wheat field. M. nivale formed characteristic pinkish colonies on the selective medium in the case of contamination with other filamentous fungi, making differentiation easy. Overall, the findings show that LATTS medium developed in this study is effective for isolation of airborne spores of M. nivale. © 2013 KNPV.


Tanaka Y.,Hokkaido Research Organization Tokachi Agricultural Experiment Station | Yumoto S.,Akita
Plant Production Science | Year: 2010

Days from full maturity to combine harvest maturity (DFC) is a major concern in combine harvesting of soybeans (Glycine max (L.)), especially in northern Japan, which has a short harvesting period. The combine harvest maturity, which was defined as the day at which the moisture content of the stem reached 30%, was analyzed using 7 soybean varieties for 3 yr in Hokkaido. There were significant differences in DFC among varieties (12 to 31 d) and among the 3 yr (16 to 25 d). DFC was closely associated with dry matter partitioning to stem (DMPS) at full maturity, that is, high DMPS increased DFC. The relationship between DMPS and DFC was examined by pod removal experiments conducted for 2 yr. In the soybean plants with high DMPS pod removal increased the stem desiccation period and DFC. These results indicated that DMPS at full maturity is an informative indicator for predicting the harvest maturity in the combine harvesting system.


Kushida A.,Japan National Agriculture and Food Research Organization | Tazawa A.,Hokkaido Research Organization Tokachi Agricultural Experiment Station | Aoyama S.,Hokkaido Research Organization Kamikawa Agricultural Experiment Station | Tomooka N.,Japan National Institute of Agrobiological Science
Genetic Resources and Crop Evolution | Year: 2013

Soybean cyst nematode (Heterodera glycines; SCN) is becoming a serious problem in azuki bean (Vigna angularis var. angularis) production in Hokkaido, Japan. To find sources of resistance to SCN, we screened wild relatives of azuki bean and calculated "female indices" (FIs) of 342 accessions from 8 Vigna species that are cross-compatible with azuki bean. Twenty-three accessions belonging to V. hirtella, V. minima, V. nakashimae, V. riukiuensis, and V. tenuicaulis were resistant to the most prevalent SCN race, race 3, but most of them were only moderately resistant or susceptible to race 5. Four promising accessions (V. minima JP205886, JP205891, and JP210806, and V. nakashimae JP107879) showed a high level of resistance to all SCN races found in Japan (1, 3, and 5) and race 2 (an experimentally derived race from race 5). Since the SCN-resistant soybean cultivars released in Japan are not resistant to races 2 and 5, these wild Vigna accessions may have resistance mechanisms different from that of soybean. Continuous culture of race 3 on promising accessions showed that it might be difficult to overcome the resistance of these accessions. The resistance sources found in this study will be useful in controlling SCN through the breeding of SCN-resistant azuki bean cultivars. This study also showed the effectiveness of using wild genetic resources for identifying novel resistance sources. © 2012 The Author(s).

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