ABSTRACT. Powdery mildew (Pm) is one of the most harmful diseases in wheat. Three Pm-resistance genes, Pm3, Pm21, and Pm8, have been cloned but most Pm3/Pm8 alleles have lost their resistance to Pm in hexaploid wheat. In this study, a new Pm3 homolog gene (TmPm3) was isolated from Triticum monococcum L. using a homology-based cloning strategy, being the first report of a functional Pm3 homolog gene from a diploid wheat species. The transient expression of TmPm3 in leaf epidermal cells showed that over-expressed TmPm3 could significantly inhibit the penetration of Blumeria graminis f. sp tritici conidia spores and the formation of haustoria. Sequence analysis of Pm3 alleles shed new light on the evolution of Pm3 genes, providing a better understanding of the molecular basis of disease resistance. This study also suggested that homology-based cloning of resistance genes is a feasible method for the isolation of functional resistance genes from wheat germplasm.

ABSTRACT.A strikingly upregulated expressed sequence tag was screened from regenerating rat liver at 8 h in a 0-4-8-12 h short-interval successive partial hepatectomy model from a previous study. In the present study, a full-length open reading frame (ORF) corresponding to this expressed sequence tag was predicted through electronic cloning and was subsequently cloned from an 8-h rat regenerating liver and deposited in GenBank (accession No. HM448398). Sequence analysis of HM448398 and the predicted ORF revealed that the two ORFs may be different transcripts of a gene. The sequence of HM448398 was highly homologous to that of rat Serpina3n, suggesting that it may be a homolog of Serpina3n. The pGEX-2TK prokaryotic expression vector for this ORF was constructed, and the result of sodium dodecyl sulfate polyacrylamide gel electrophoresis manifested that the recombinant expression vector could express the glutathione-S-transferase-fused rat homolog of Serpina3n in an insoluble form in BL21. The target fusion protein was purified with affinity chromatography and was used as antigen to immunize rabbits for the production of polyclonal antibodies. Immunohistochemistry and real-time reverse transcription polymerase chain reaction analysis revealed that the gene was highly expressed in the priming and termination phases of liver regeneration. These findings lay a solid foundation for further study of roles of HM448398 using knock-in and RNA interference methods during liver regeneration.