Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2002
Publication Date: 1/1/2003
Citation: THARA,V.K., FELLERS,J.P., ZHOU,J., IN PLANTA INDUCED GENES OF PUCCINIA TRITICINA, MOLECULAR PLANT PATHOLOGY, 2003. 4:51-56. Interpretive Summary: DNA sequencing and other advances in gene evaluation are opening doors into the understanding of how plants and fungi interact. There is a wealth of knowledge of how the plants react, but little is known about what genes the fungi uses to infect a plant. This work describes a set of genes from a fungus that causes leaf rust in wheat. We show which genes are turned on and which are turned off. By sequence comparisons to a database, we can assign some functions to some of the genes. However, most do not have a known function. Future work will include studies to assign the function of these genes. This information could be used to develop novel types of disease resistance.
Technical Abstract: Wheat leaf rust disease, caused by the biotrophic fungus Puccinia triticina, is a result of complex interactions requiring the coordinated activities of the two organisms involved. In an effort to understand the molecular basis of wheat¿rust interactions, we isolated and characterized cDNA corresponding to in planta induced fungal genes (PIGs) from susceptible wheat leaves infected with P. triticina by using suppression subtractive hybridization to construct a cDNA library. 350 clones were sequenced, of which 104 were unique. Forty-four cDNA clones encode ribosomal proteins, comprising the single largest category of clones isolated. Twenty-five of these ribosomal protein genes are likely to be of fungal origin, as was suggested by sequence homology. Hybridization of 56 selected non-ribosomal protein clones to rust germling cDNA or genomic DNA probes showed that at least 44 were of fungal origin, demonstrating that the library was highly enriched for fungal cDNA. Differential expression analysis identified 26 non-ribosomal protein genes that were induced in rust infected leaves. At least 21 of the induced genes were from the rust fungus, indicating that the majority of the induced genes were rust PIGs that are likely to play a role in parasitism. Some of the induced genes share homology to known PIGs or virulence genes in other fungi, suggesting similarities in parasitism among different fungi. Eight clones correspond to novel PIGs that have not been reported in any organism. This paper reports, for the first time, the isolation of P. triticina PIGs and discusses the use of total rust genomic DNA to identify the source of genes.