Root and crown rot of strawberry caused by Pythium helicoides and its distribution in strawberry production areas of Japan

Pythium species were isolated from seedlings of strawberry with root and crown rot. The isolates were identified as P. helicoides on the basis of morphological characteristics and sequences of the ribosomal DNA internal transcribed spacer regions. In pathogenicity tests, the isolates caused root and crown rot similar to the original disease symptoms. Multiplex PCR was used to survey pathogen occurrence in strawberry production areas of Japan. Pythium helicoides was detected in 11 of 82 fields. The pathogen is distributed over six prefectures.     

DNA methylation analysis on satellite I region in blastocysts obtained from somatic cell cloned cattle

Many observations have been made on cloned embryos and on adult clones by somatic cell nuclear transfer (SCNT), but it is still unclear whether the progeny of cloned animals is presenting normal epigenetic status. Here, in order to accumulate the information for evaluating the normality of cloned cattle, we analyzed the DNA methylation status on satellite I region in blastocysts obtained from cloned cattle. Embryos were produced by artificial insemination (AI) to non‐cloned or cloned dams using semen from non‐cloned or cloned sires. After 7 days of AI, embryos at blastocyst stage were collected by uterine flushing. The DNA methylation levels in embryos obtained by using semen and/or oocytes from cloned cattle were similar to those in in vivo embryos from non‐cloned cattle. In contrast, the DNA methylation levels in SCNT embryos were significantly higher (P < 0.01) than those in in vivo embryos from non‐cloned and cloned cattle, approximately similar to those in somatic cells used as donor cells. Thus, this study provides useful information that epigenetic status may be normal in the progeny of cloned cattle, suggesting the normality of germline cells in cloned cattle.     

Resistance in leaf blades assessed by counting conidia correlates with whole-plant-specific resistance in leaf sheaths in a compatible rice–Magnaporthe oryzae interaction

Resistance in the leaf blades of rice plants against a virulent race of the rice blast fungus Magnaporthe oryzae was quantitatively examined using a modified spot inoculation method. Numbers of conidia produced in the lesions were affected by plant age and paralleled the frequency of resistance infection types, which is indicative of whole-plant-specific resistance (WPSR), in the inoculated leaf sheaths of the corresponding plants. Exogenous abscisic acid treatment, which suppresses WPSR, also increased the susceptibility of the leaf blades. These results indicate a correlation between the resistance of the leaf blades and the WPSR in the leaf sheaths.     

First report of celery stunt anthracnose caused by <Emphasis Type="Italic">Colletotrichum simmondsii</Emphasis> in Japan

A new disease was found in Japan, on celery (Apium graveolens var. dulce) having severe chlorotic leaf spot, stunt, and dwarf with leaf curl. A spore suspension from the fungus isolated from affected plants induced identical symptoms 14 days after plants were sprayed. Identification and molecular characterization showed that the causal agent is Colletotrichum simmondsii. This report is the first of stunt anthracnose on celery caused by C. simmondsii. We propose the name “stunt anthracnose” for the new disease. Colletotrichum acutatum sensu lato, as reference pathogen of celery anthracnose, should be changed to C. fioriniae based on morphological and molecular characteristics.     

Physiological Races and Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae Isolated from Crisphead Lettuce in Japan

One hundred and sixteen isolates of Fusarium oxysporum f. sp. lactucae obtained from 85 fields in three crisphead lettuce-producing areas in Nagano Prefecture, Japan were typed for races using differential cultivars Patriot, Banchu Red Fire and Costa Rica No. 4. They were also grouped into vegetative compatibility groups (VCGs) using complementation tests with nitrate non-utilizing (nit) mutants. Two California strains reported as F. oxysporum f. sp. lactucum, a type culture of F. oxysporum f. sp. lactucae, and 28 avirulent isolates of F. oxysporum obtained from crisphead lettuce were included for comparison. Among Nagano isolates, 66 isolates were identified as race 1, and 50 as race 2. Race 1 strains derived from Shiojiri and Komoro cities and race 2 from Kawakami village and Komoro city. All isolates of race 2 were biotin auxotrophs, and the race could be distinguished based on its requirement for biotin on minimal nitrate agar medium (MM). Pathogenic isolates were classified into two VCGs and three heterokaryon self-incompatible isolates. Strong correlations were found between race and VCG. All the race 1 strains were assigned to VCG 1 except self-incompatible isolates, and all the race 2 strains to VCG 2. The 28 avirulent isolates of F. oxysporum were incompatible with VCG 1 and VCG 2. California strains was vegetatively compatible with VCG 1, and they were assigned to race 1. Based on vegetative compatibility, these two races of F. oxysporum f. sp. lactucae may be genetically distinct, and F. oxysporum f. sp. lactucae race 1 is identical to F. oxysporum f. sp. lactucum. Received 7 May 2002/ Accepted in revised form 6 September 2002     

An avirulence gene homologue in the tomato wilt fungus Fusarium oxysporum f. sp. lycopersici race 1 functions as a virulence gene in the cabbage yellows fungus F. oxysporum f. sp. conglutinans

Six4, a small protein secreted by Fusarium oxysporum f. sp. lycopersici (Fol) in tomato xylem sap during infection, triggers Fol race 1-specific resistance (I) in tomato. SIX4 is regarded as an avirulence gene. Although SIX4 is considered unique to Fol race 1, we detected this gene in the cabbage yellows fungus F. oxysporum f. sp. conglutinans (Foc) by PCR. Because the genes from Foc and SIX4 in Fol were >99 % identical at the nucleotide level, the Foc gene was designated FocSIX4. The expression of FocSIX4 was detected by RT-PCR in stems and roots of cabbage 8 days after infection with Foc. In contrast with Fol, disruption of FocSIX4 in Foc did not increase virulence to Foc-resistant cabbage cvs. Shutoku-SP and Koikaze. On the contrary, the disruptants had reduced virulence not only on Foc-resistant cultivars but also on Foc-susceptible cv. Shikidori. These results suggested that FocSIX4 is involved in virulence, but not in avirulence, in the cabbage yellows fungus.     

Regional variability in landscape effects on forest bird communities

Landscape Ecology - Functional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique...     

An evaluation of one example of biotope roof in Japan: Plant development and invertebrate colonisation after 8 years

Biotope roofs in Japan are usually intensive green roofs that primarily include native plants and food plants for invertebrates and a pond and stones to create a wide range of habitats. The study aimed to evaluate the survivability of planted species, and colonisation by plants and invertebrates on a biotope roof and to suggest an appropriate planting design and maintenance scheme to optimize biodiversity benefits. An intensive green roof (150 m², substrate depth of 50 cm) was installed in 2002 on the ninth storey of a building at Chiba University, Japan. Twelve species of trees, 18 species of shrubs and 8 species of forbs (mainly native species) were planted and volcanic stones were used as mulch and to create habitats for invertebrates. No maintenance and no irrigation were applied for almost 8 years. A limited number of tree species, such as Myrica rubra and Cinnamomum camphora could grew well without maintenance and irrigation at a substrate depth of 50 cm. Overall, shrubs grew successfully and a high density planting seemed effective in increasing wind resistance. Most forbs disappeared, probably because of drought and competition with these colonising plants. Eleven plant species spontaneously colonised resulting in domination by Solidago altissima and Miscanthus sinensis. These two species were too aggressive, and selective weeding is required for species richness. In an invertebrate study, 46 species in 11 orders were observed and the highest number of invertebrate species was observed in the pond and shady areas.     

Expression of CD4 T cell cytokine genes in the colorectal mucosa of inflammatory colorectal polyps in miniature dachshunds

Inflammatory colorectal polyps (ICRPs) in miniature dachshunds are recently recognized as a major cause of large bowel diarrhea in this dog breed in Japan. ICRPs are characterized by the formation of multiple small polyps and a space-occupying large polyp in the colorectal area, and are thought to be a novel form of inflammatory bowel disease (IBD). In humans, specific cytokine patterns attributed to T helper (Th)1, Th17 and regulatory T cells have important roles in the pathogenesis of IBD. Thus, the aim of the present study was to assess the gene expression of cytokines of T cell subsets in the colorectal mucosa from dogs with ICRPs. Colorectal mucosal specimens from 10 dogs with ICRPs and 14 control dogs were used in this study. Interferon (IFN)-γ, interleukin (IL)-4, IL-17A and IL-10 mRNA expression was assessed using quantitative real-time PCR. IL-17A mRNA expression was significantly increased in large polyps compared to small polyps and controls. IFN-γ and IL-10 mRNA expression in large polyps were significantly higher than in controls. There was no significant difference in IL-4 mRNA expression among the three groups. IL-17A is thought to play important roles in the pathogenesis of ICRPs. IL-10 up-regulation could oppose the proinflammatory function of IL-17A.