Kiroku Kobayashi

Wilt-inducing antibiotic compounds produced by Cephalosporium gregatum.

Five metabolites were isolated from the culture filtrate of a clone of Cephalosporium gregatum from diseased adzuki beans. The phytotoxicity and antibiotic activity of these compounds were tested. Among the compounds, which were characterized as derivatives of tetronic acid and designated Gregatin A, B, C, D and E, Gregatin A, C and D produced wilting, death of leaves and vascular browning of adzuki bean and mung bean cuttings. These same compounds produced leaf wilting but no vascular browning in soybean and kidney bean cuttings, thus confirming the results of earlier pathogenicity trials on specificity of the adzuki bean pathogen to adzuki beans. The results suggest a possible role for Gregatin A, C and D in pathogenesis. Gregatin A, and to a lesser extent C and D, were also inhibitory to a wide range of fungi and bacteria in antibiotic tests.

Phytotoxicity and antimicrobial activity of graminin A, produced by Cephalosporium gramineum, the causal agent of Cephalosporium stripe disease of wheat

Abstract A new phytotoxic compound, Graminin A, was isolated from the culture filtrate of Cephalosporium gramineum. The phytotoxicity and antimicrobial activity of this compound were tested. Graminin A produced chlorosis and browning of leaves and vascular tissues of wheat cuttings at low concentrations. It had little or no effect on cuttings of non-host plants such as bean, tomato, eggplant and corn. The results suggested that Graminin A may be involved in the expression of the syndrome of Cephalosporium stripe of wheat. Graminin A also inhibited the growth of many fungi and bacteria.

Ultrastructural changes during the symbiotic development of Spiranthes sinensis (Orchidaceae) protocorms associated with binucleate Rhizoctonia anastomosis group C

The process of symbiotic development of Spiranthes sinensis seeds to protocorms with differentiated shoots associated with binucleate Rhizoctonia anastomosis group C was divided into 7 stages (I–VII) based on increase of embryo and protocorm width. Each stage was observed ultrastructurally. The embryo contained large amount of lipid, small amount of starch, and protein body-like structure in all its cells. The embryo began to swell (stage I) as soon as several hyphae invaded the basal cells. Hyphae penetrated into the inner cortical parenchyma (ICP) and subepidermal parenchyma (SEP) cells and formed pelotons. The meristematic region (MR) was not colonized. Hyphal cell walls (FCW) were surrounded by an encasement layer (EL) and by the host plasmalemma. Pelotons that formed in ICP had thin walls and were digested, whereas pelotons in SEP were not digested. In stage I, mitochondria, ribosomes, proplastids, microbodies, rough endoplasmic reticulum, dictyosomes and vacuoles were observed in the host cytoplasm. Signs of hyphal digestion was already apparent in this stage. In stage II, clumps of digested pelotons consisted only of layers of FCW and EL and were surrounded by host cytoplasm and vacuoles, and/or secondary infected hyphae. Hyphal digestion and the reinfection of host cells occurred repeatedly throughout all growth stages. Protein body-like structures rapidly disappeared before stage III. At stage V and subsequent stages, it was also seen that the dispersed contents of digested hyphae were surrounded by the host plasmalemma. When ICP cells contained pelotons, amyloplasts were not observed. However, proplastids usually existed in the cells, and amyloplasts were observed in all SEP cells and other uninfected cells. Lipid bodies were slowly degraded throughout embryo and protocorm growth.

INFLUENCE OF THE SOYBEAN CYST NEMATODE (HETERODERA GLYCINES) ON THE INCIDENCE OF BROWN STEM ROT IN SOYBEAN AND ADZUKI BEAN

Summary-Experiments were carried out in pots to study the influence of the soybean cyst nematode (Heterodera g/y&es) on the incidence of brown stem rot (BSR) in soybeans (Glycine max) and adzuki beans (Vigna angularis) caused by the soilbome fungi, Phialophora gregata fsp. sojae and P. g. f.sp. adzukicola. The presence of H. glycines increased the incidence of BSR in susceptible soybean (cv. Nakate-Hikarikuro) and adzuki bean (cv. Erimoshozu) for both pathogens. The disease-enhancing effects of H. glycines were not shown in the soybean cultivar Peking, which is resistant to the nematode. In a soybean cultivar resistant to BSR (cv. BSR302), the incidence of BSR was low, even under the presence of H. glycines. In split-root experiments using the two BSR susceptible cultivars, the diseaseenhancing effects of H. glycines were not observed in either soybeans or adzuki beans, whose roots were inoculated separately with P. gregata and H. glycines. 0 1997 Elsevier Science Ltd

Morphological and physiological comparisons of Helicobasidium mompa and H. purpureum

Morphological and physiological comparisons were made of sevenHelicobasidium mompa isolates and fourH. purpureum isolates. Colonies of theH. mompa isolates were thin, dense, or hard and dense, and most were pale brown to brown or dark brown, while that of isolate 344c was pinkish. Colonies ofH. purpureum isolates were hard and dense, and their colonies were dark brown. Diameters of hyphae were similar forH. mompa andH. purpureum. Dimensions of conidia and morphology of conidiophores ofH. mompa isolate 344c were close to those ofH. purpureum reported previously.H. mompa isolates grew well at 23°C, 25°C or 27°C, while all isolates ofH. purpureum grew well at 23°C. Growth rates ofH. purpureum isolates was almost the same as those ofH. mompa isolates with slow growth. Polygaracturonase activity at pH 3 was variable among the isolates for bothH. mompa andH. purpureum. Itaconic acid was produced abundantly by three isolates ofH. mompa but not produced by isolate AH130, whereas all isoaltes ofH. purpureum produced a small amount of itaconic acid.

Characterization of the nuclear DNA of Phialophora gregata ff.sp, adzukicola and sojae

Phialophora gregata nuclear (n) DNA was characterized by physical methods. The nDNA of f.sp.adzukicola was shown to be larger than that of f.sp.sojae, 2.9 and 2.1 × 1010 Da, respectively. The amounts of repetitive sequence and AT-rich region in the nDNA were also larger in f.sp.adzukicola than f.sp.sojae. These results indicate that the nuclear genome organization of the two formae speciales is differentiated.

Isolation and Structure of a New Diprenyl Phenol, Colletorin B Produced by Cephalosporium diospyri

Isolation and Structure of a New Diprenyl Phenol, Colletorin B Produced by Cephalosporium diospyri Hirokazu Kawagishi, Hiroji Sato, Sadao Sakamura, Kiroku Kobayashi & Ui Tadao To cite this article: Hirokazu Kawagishi, Hiroji Sato, Sadao Sakamura, Kiroku Kobayashi & Ui Tadao (1984) Isolation and Structure of a New Diprenyl Phenol, Colletorin B Produced by Cephalosporiumdiospyri, Agricultural and Biological Chemistry, 48:7, 1903-1904, DOI: 10.1080/00021369.1984.10866421 To link to this article: https://doi.org/10.1080/00021369.1984.10866421

Differential Growth Response of A1 and A2 Mating Types of Phytophthora infestons on Rye A and V-8 Juice Agar Media Supplemented with Rhizome Powder of Cyperus rotundus

A new medium for studies of diversity among populations of A1 and A2 mating types of Phytophthora infestons has been evolved. The rye A agar and V-8 juice agar media on which P. infestons grows well have been amended with rhizome powder of Cyperus rotundus. A total of 259 isolates of A1 and A2 mating types representing Japan, Korea, India, Taiwan, Indonesia, Thailand, China, Nepal, U.K. and Mexico were screened for their growth response on these two media. Most of the A1 isolates did not grow well on them except Thailand while growth of A2 mating types differed as some grew on it whereas others did not. It is quite likely that the populations of A2 mating types that did not grow well on rhizome-amended medium are of different clonal lineage. This suggests that this medium can be used for the study of diversification among the isolates of the same or both the mating types as well as to detect the newly introduced genetically different isolates of P. infestans in a locality where it was not reported earlier.