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Abstract??A lesion mimic mutant that we designatedSpotted leaf 18(Spl18) was isolated from 13,000 activation-tagging lines of rice produced by our modified activation-tagging vector and further characterized.Spl18was dominant and its phenotype was linked to the T-DNA insertion. An ORF was located about 500?bp downstream of the inserted T-DNA, and the deduced protein, designated OsAT1, showed sequence similarity to an acyltransferase whose expression is induced by hypersensitive reaction in tobacco. The transcriptional level ofOsAT1was very low in the WT leaf blade but high inSpl18leaf blade. In wild-type rice,OsAT1was transcribed mainly in the young panicle, in the panicle just after heading, and in the leaf sheath. In addition, transcription of the genes for PR protein was upregulated inSpl18, accumulation of phytoalexins (both momilactone A and sakuranetin) was increased, and resistance to blast disease was improved. We then combinedOsAT1genomic DNA downstream of the modified 35S promoter and re-transformed it into rice. Lesion mimic and blast resistance phenotypes were detected in the transgenic lines produced, clearly indicating that overexpression ofOsAT1caused theSpl18phenotypes. In addition, plants overexpressingOsAT1showed resistance to bacterial blight. [ABSTRACT FROM AUTHOR]

To clarify the geographic variation and isolate specificity in blast resistance, 20 cultivars of foxtail millet (Setaria italica (L.) P. Beauv.) originating from Eurasia were examined for their resistance using 11 Japanese Setaria isolates of blast fungus. Cultivars from the countries east of Pakistan generally showed resistance to most of the 11 fungus isolates, whereas those from the countries west of Afghanistan indicated higher susceptibility. The origin of this geographical regularity was discussed in relation to the deficiency or specificity of relevant resistance gene(s). No identical reaction pattern was observed among cultivars, indicating their highly distinctive isolate specificity. The virulence of isolates was also diverse, since only 2 out of 10 virulent isolates were identical for their reaction patterns. Preliminary genetic analysis of blast resistance to four fungus isolates suggests that they are governed by more than two dominant genes. [ABSTRACT FROM AUTHOR]

In plants, calcium acts as a universal second messenger in various signal transduction pathways. The plant-specific calcium-dependent protein kinases (CDPKs) play important roles regulating downstream components of calcium signaling. We conducted a genome-wide analysis of rice CDPKs and identified 29 CDPK genes and eight closely related kinase genes, including five CDPK-related kinases (CRKs), one calcium and calmodulin-dependent protein kinase (CCaMK) and two phosphoenolpyruvate (PEP) carboxylase kinase-related kinases (PEPRKs). The mRNA splicing sites of the rice CDPKs, CRKs and PEPRKs (but not OsCCaMK) are highly conserved, suggesting that these kinases are derived from a common ancestor. RNA gel blot analyses revealed that the majority of rice CDPK genes exhibited tissue-specific expression. Expression of OsCPK9 was elevated in seedlings infected by rice blast, indicating that this gene plays an important role in signaling in response to rice blast treatment. Our genomic and bioinformatic analyses will provide an important foundation for further functional dissection of the rice CDPK gene family. [ABSTRACT FROM AUTHOR]