The significance of light irradiation in Sekiguchi lesion (SL) formation by infection with Magnaporthe grisea on rice cv. Sekiguchi-asahi was investigated. When the leaf blades of cv. Sekiguchi-asahi inoculated with M. grisea spores were kept under different wavelengths of light. SLs were formed under visible light regardless of the compatibility between fungal race and cv. Sekiguchiasahi. On the contrary, typical blast and or nectrotic spot lesions were formed under near ultraviolet radiation from the black light fluorescent lamps and near infrared radiation from infrared fluorescent lamps. The effective wavelength for light-dependent SL formation was 400-700 nm. Furthermore,thelongerthe wavelength of radiation, the bigger were the SLs. Such light-dependent induction of the SL was suppressed by pretreatment of 3-(3,4-dichlorophenyl)-l ,1-dimethylurea (DCMU) and cycloheximide (CY). These results suggested that photosynthetic and protein synthetic activities were involved in SL formation. Zusammenfassung Die Einfliisse des Lichtes sowie Photo-und ProteinsyntheseInhibitoren auf die Bildung von "Sekiguchi-Lasionen" durch Magnaporthe grisea in Reis der Sorte Sekiguchi-asahiUntersucht wurde die Bedeutung des Lichtes bei der Bildung von "Sekiguchi-Lasionen" (SL) bei der Reissorte Sekiguchi-asahi nach einer Infektion mit Magnaporthe grisea. Nach einer M. grrw^a-Inokulation von Blattern der Sorte Sekiguchi-asahi, die bei unterschiedlichen Lichtwellenlangen anschlieBend inkubiert worden waren, wurden SLs im sichtbarem Lichtbereich gebildet, unabhangig von der Kompitabiitat der Pilzrasse mit der Sorte Sekiguchi-asahi. Im Gegensatz dazu wurden fypische *This study is part 13 in series. Studies oti host-selective infection mechanism of Magnaporthe grisea (Hebert) Barr. atid was supported in part by Grant-in-aid for Research (Nos. 07660058 and 08660057) from the Ministry of Education. Science and Culture of Japan.Reisbrandflecken und/oder nekrotische Lasionen unter Nah-UV-Licht ("Schwarzlicht") bzw. Nah-InfrarotLicht gebildet. Die wirksame Wellenlange fur eine lichtabhangige SL-Bildung lag zwischen 400 und 700 nm. Es wurde auBerdem beobachtet, dafl je langer die Bestrahlungswellenlange, desto grofler die SLs waren. Diese lichtabhangige Induktion der SL-Bildung konnte durch eine Vorbehandlung mit 3-(3,4-Dichlorophenyl)-1,1 -Dimethylharnstoff (DCMU) sowie mit Cycloheximid (CY) unterdriickt werden. Diese Ergebnisse deuten daraufhin, daB sowohl photosynthetische als auch proteinsynthetishche Aktivitaten mit der SL-Bildung gekoppelt sind. IntroductionMagnaporthe grisea (Hebert) Barr (= Pyricularia oryzae Cavara) is the pathogen of rice blast disease which is one of the most important plant diseases in Japan. Resistance and susceptibility of rice plants to M. grisea are determined by the interaction between fungal race and rice cultivar (Yamada et al., 1976). When M. grisea infects rice leaves, it forms lesions which are brown and typically elliptical with more or less pointed ends. However, the mutant rice cv. Sekiguchi-asahi, whi...
The significance of light irradiation in neerosis formation by Magnaporthe grisea toxin(s) on rice cv. Sekiguchi‐asahi was investigated. The effective wave region for light‐dependent neerosis formation was 400 700 nm. An absorption band of the toxin(s) was restricted to the wave region shorter than 400 nm. Both of the phytosynthesis and necrosis formation were inhibited by photosynthetic inhibitors, and the inhibition of both activities was dependent on concentration of the inhibitors. The necrosis formation by the toxin(s) depended on light intensity. The toxin(s) induced the necrosis formation only on the cells with many chloroplasts, and the cells without chloroplasts did not form necrosis even under the light with sufficient intensity. The more the number of chloroplasts decreased, the more the size of necrotic spot decreased on the leaf sheath. From these results we concluded that the photosynthetic activity was involved in the necrosis formation by Magnaporthe grisea toxin(s) in rice cv. Sekiguchi‐asahi.
Microprotrusions, or cones, grown on monocrystalline Si obliquely sputtered with Ar+ ions, while being supplied with Ni ‘‘seeds’’ by sputtering, were observed by scanning and transmission electron microscopy. At temperatures lower than 400 °C, Ni atoms were deposited on the upper cone slope receiving the high fluxes of seeds, resulting in the development of ‘‘delta-winged’’ cones. Seed layers were Ni for substrate temperatures below 200 °C and nickel silicide for temperatures above 200 °C, and they were silicidized to NiSi2 above 300 °C, suggesting that Ar+ bombardment activated the NiSi2 formation at the growth front of seed-layer tip. Cones were grown heteroepitaxially at 400 °C, consisting of alternating NiSi2 and Si layers. We thus consider that a controlled particle supply process was involved in Ar+ bombardment at 400 °C. Evidence is also presented that impacting Ar+ ions induced an eutectic reaction between Ni and Si around 500 °C.
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