Cloning of a novel phosphateserine aminotransferase gene from a Triticum aestivum-Elytrigia elongatum alien substitution line with resistance to powdery mildew

Shannong 551, a T. aestivum-E. elongatum alien substitution line with resistance to powdery mildew, was in- oculated with pathogenic spores of powdery mildew. The leaf samples were prepared 48 h after inoculation for scanning electron microscopy. The result showed that germination of spores and growth of young mycelia on leaves of Shannong 551 were suppressed at the early stage of infection. At the same time, RNAs were prepared from the leaves for the cloning of WRP1 and RPW2 by cDNA RDA and RACE tech- nology. BLAST analysis of the sequences indicated that both WRP1 and RPW2 were novel genes. WRP1 contains no com- plete ORF. RPW2 contains the conserved structure domain of aminotransferase, and its DNA sequence shares high homol- ogy with genes of phosphateserine aminotransferase in many organisms. Therefore, it is speculated as a novel phosphate- serine aminotransferase gene. The results of Northern blot suggested that expression of RPW2 occurred at the early stage of infection by powdery mildew. Southern blot using the probe of RPW2, in which there was strong hybridizing sig- nals in both genome of Shannong 551 and E. elongatum, but not in those of Jinan 13 and Lumai No.5, indicated that RPW2 derived from the genome of E. elongatum.

Shannong 551, a T. aestivum-E. elongation alien substitution line withresistance to powdery mildew, was inoculated with pathogenic spores of powdery mildew. The leafsamples were prepared 48 h after inoculation for scanning electron microscopy. The result showedthat germination of spores and growth of young mycelia on leaves of Shannong 551 were suppressed atthe early stage of infection. At the same time, RNAs were prepared from the leaves for the cloningof WRP1 and RPW2 by cDNA RDA and MACE technology. BLAST analysis of the sequences indicated thatboth WRP1 and RPW2 were novel genes. WRP1 contains no complete ORE RPW2 contains the conservedstructure domain of aminotransferase, and its DNA sequence shares high homology with genes ofphospfaateserine aminotransferase in many organisms. Therefore, it is speculated as a novelphosphate-serine aminotransferase gene. The results of Northern blot suggested that expression ofRPW2 occurred at the early stage of infection toy powdery mildew. Southern blot using the probe ofRPW2, in which there was strong hybridizing signals in both genome of Shannong 551 and E. elongatum,but not in those of Jinan 13 and Lumai No.5, indicated that RPW2 derived from the genome of E.elongatum.