The eds5 mutant of Arabidopsis (earlier named sid1 ) was shown previously to accumulate very little salicylic acid and PR-1 transcript after pathogen inoculation and to be hypersusceptible to pathogens. We have isolated EDS5 by positional cloning and show that it encodes a protein with a predicted series of nine to 11 membrane-spanning domains and a coil domain at the N terminus. EDS5 is homologous with members of the MATE (multidrug and toxin extrusion) transporter family. EDS5 expression is very low in unstressed plants and strongly induced by pathogens and UV-C light. The transcript starts to accumulate 2 hr after inoculation of Arabidopsis with an avirulent strain of Pseudomonas syringae or UV-C light exposure, and it stays induced for ‫ف‬ 2 days. EDS5 also is expressed after treatments with salicylic acid, indicating a possible positive feedback regulation. EDS5 expression after infection by certain pathogens as well as after UV-C light exposure depends on the pathogen response proteins EDS1, PAD4, and NDR1, indicating that the signal transduction pathways after UV-C light exposure and pathogen inoculation share common elements. INTRODUCTIONPlants react to an attack by phytopathogenic microorganisms with an array of inducible defense responses. Whether a plant is resistant or susceptible to a potential pathogen depends largely on how fast a pathogen is recognized and defense responses are activated. For instance, in gene-forgene resistance, the product of an avirulence gene of the pathogen is recognized by a corresponding resistance gene product of the plant, leading to the rapid activation of various defense responses. Such a pathogen is avirulent to the plant, its invasion can be stopped, and the plant is resistant. Disease ensues when the pathogen is not recognized rapidly and defense mechanisms are activated too slowly to stop the infection process. In this case, the pathogen is virulent and the plant is susceptible. In addition, defense responses can be induced systemically in all parts of the plant by pathogens, soil-borne microorganisms, chemicals, or certain forms of stress. This form of induced resistance is referred to as systemic acquired resistance Sticher et al., 1997).Salicylic acid (SA) is synthesized after inoculation of plants with pathogens or exposure to certain abiotic stresses, such as ozone and UV-C light. SA was found to be essential for gene-for-gene resistance, systemic acquired resistance, and reduction of disease development after inoculation with virulent pathogens (Delaney et al., 1994;Nawrath and Métraux, 1999).In Arabidopsis, the elucidation of the signal transduction pathway downstream of SA leading to the expression of a number of pathogenesis-related (PR) proteins, such as PR-1 , PR-2 , and PR-5 , has been centered on the characterization of the npr1/nim1 mutant (Cao et al., 1994;Delaney et al., 1995). The npr1/nim1 mutant does not express PR-1 , PR-2 , and PR-5 after treatment with SA analogs, such as isonicotinic acid (Cao et al., 1994;Delaney et al., 1995). However, when...

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An actinobacterial strain, DCWR9-8-2(T), was isolated from a leaf of Thai upland rice (Oryza sativa) collected in Chumporn province, Thailand. Strain DCWR9-8-2(T) is Gram-stain-positive aerobic bacteria that produce single spores directly on the vegetative hypha. Cell wall peptidoglycan of this strain exhibits meso-diaminopimelic acid and glycine, the reducing sugars of whole-cell hydrolysate are arabinose, glucose, ribose, xylose and small amount of mannose. The phospholipid profiles in the membrane are comprised of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides. The major menaquinones are MK-9(H4) and MK-10(H6). The diagnostic cellular fatty acids are iso-C16:0 and iso-C15:0. The G+C content of the genomic DNA is 72.5 mol%. The result of 16S rRNA sequence analysis of the strain revealed that this strain was closely related to Micromonospora auratinigra TT1-11(T) (99.25%). On the other hand, the result of gyrB gene sequence analysis revealed that this strain was closed to M. eburnea JCM 12345(T) (96.30%). In addition, a combination of DNA-DNA hybridization results and some phenotypic properties supported that this strain should be judged as a novel species of the genus Micromonospora, for which the name M. endophytica sp. nov. is proposed. The type strain is DCWR9-8-2(T) (=BCC 67267(T)=NBRC 110008(T)).

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