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ABSTRACT
Kaku, H. 2004. Hislopathology of red stripe of rice. Plant Dis. 88:1304-1309.
A histological study of red stripe of rice was conducted to elucidate the mode of infection of the causal bacterium Microbacterium sp. When pin-point-sized spots first appeared at 3 days after inoculation, the bacterial cells had entered through stomata and multiplied in the intercellular spaces of substomatal parenchymatous tissues. With the early appearance of small yellow spots al 4 to 5 days after inoculation, the bacterium was detected in some xylem vessels as well as in parenchymatous tissues, and it had apparently translocated directly from parenchymatous tissues to transverse vascular systems through spiral vessel walls. With the appearance of typical red stripe symptoms comprised of orange lesions and halos at 8 days after inoculation, bacterial masses were present in transverse and longitudinal vascular bundles in areas with orange lesions. In the areas with orange to light brown spots, granules that stained dark blue using Stoughton's method appeared in the protoplasm of the host parenchymatous cells, which later became necrotic. In halo areas, bacterial masses were observed only in some cases, and chloroplasts were disorganized. Bacterial infection was also confirmed by observing sections of naturally infected samples, and the distribution of bacteria was much more extensive than in artificially inoculated samples.
Additional keywords: plant-pathogenic coryneform
Red stripe is a serious diseuse of nee (Oryza sativ) that has been spreading in intensive rice production areas of Southeast Asia within the last decade and has caused severe damage in rice production. In Vietnam, the total infected area was 64,200 ha in 1990. and increased to 199,000 ha in 1991 and is still spreading (19). The disease was first reported in Indonesia in 1988 (13). Since then, the disease has been reported in Malaysia, Vietnam, the Philippines, and Thailand (2,12). Extensive research has been carried out in these countries with special reference to the causal agent of the disease.
In the first report on the disease, Mogi et al. (13) named it bacterial red stripe. Some bacteria have been isolated from the diseased rice plants in Indonesia and Vietnam (12,13). However, pathogenicity of the bacteria has not been confirmed. Several fungal species have also been isolated from red stripe lesions, including Curvularia lunata and...