Pseudomonas plantarii sp. nov., the Causal Agent of Rice Seedling Blight

Abstract

An aerobic, gram-negative bacterium that causes seedling blight of rice was isolated from diseased rice seedlings and bed soil in nursery boxes in Chiba and Niigata Prefectures, Japan. The cells are nonsporeforming and nonencapsulated straight rods (0.7 to 1.0 by 1.4 to 1.9 μm) that occur singly, in pairs, or in short chains and are motile with one to three polar flagella. The bacterium displays the characteristics of the genus Pseudomonas and can be clearly differentiated from Pseudomonas glumae and Pseudomonas avenae, which are known to cause seedling diseases in rice grown in nursery boxes, and from other bacteria. The deoxyribonucleic acid base composition is 64.8 mol% guanine plus cytosine. A new species, Pseudomonas plantarii sp. nov., is proposed. The type strain is NIAES 1723 (JCM 5492, AZ 8201). All strains of the new species produce the disease-causing substance tropolone (a nonbenzenoid aromatic compound with a seven-membered ring) and a reddish brown pigment which was considered to be a derivative of the substance.