Expression Profiling Of Wheat Adult Plant Resistance And Race Specific Resistance Related Genes To Stripe Rust

Stripe rust, caused by Puccinia striiformis f. sp. Tritici (Pst), is a destructive disease of wheat (Triticum aestivum) worldwide. Adult plant resistance is relative to the durable resistance to stripe rust in wheat and adult plant resistance might be one of the most important component of durable resistance. To gain a better understanding of the mechanism of adult plant resistance, the suppressive subtractive hybridization (SSH) approach was used to identify wheat genes induced by Pst inoculation at adult plant stage. A total of 1,250 positive cDNA clones were obtained and sequenced. After the contig analysis with the Cap3 assembler, 427 unique sequences were obtained and compared to the NCBI no-redundant protein database using the BlastX program. The sequences were putatively categorized as genes belonging to signal transduction, transcription regulation, protein synthesis and storage, membrane transport, and cell growth and division. Based on the putative functions of the induced genes, we propose a special defense-related pathway that is triggered during the expression of adult-plant resistance in XZ after we compared our results with the research on high-temperature adult-plant (HTAP) resistance and race specific resistance in the literature. The time-course expressions using quantitative RT-PCR confirmed the induction of seven selected genes by Pst infection and determined their expression patterns.The result indicated that the expression pattern in adult plant was roughly similar to that in seedlings except the transcription level was higher and faster increased in adult plants.It is noteworthy that the expression level of most defense-related genes was higher in mock inoculated adult plant than that in mock inoculated seedlings. This might be one of the reasons for APR.The race specific resistance of wheat to stripe rust is one of important resistance in wheat breeding. In order to understand the molecular mechanism of race specific resistance, we constructed and used a custom focused oligonucleotide microarray to perform a meta-analysis of the transcriptional response involved in race-specific resistance conferred by Yr1, Yr5, Yr7, Yr8, Yr9, Yr10, Yr15, and Yr17. By profiling the response of the eight resistance genes in a common background genome, we identified 28 transcripts as significantly involved in the race-specific resistance phenotype across all genotypes, in which 19 transcrips, such as putative disease resistance protein, peroxidase, blue copper-binding protein and phenylalanine ammonia-lyase were specific to the uncompatible interaction compared to the uninoculated mock. Nine transcripts were specific to the uncompatible interaction compared to compatible interaction. These tanscripts includes calmodulin-binding protein, blue copper-binding protein, peroxidase and beta-1, 3-glucanase. Unique defense-related transcripts significant in each genotype were also identified, which highlighted some transcriptional events specific to certain genotypes. The results confirm the activity of known R-gene mediated pathways in the race-specific resistance response, including an oxidative burst that likely contributes to a hypersensitive response (HR), as well as pathogenesis-related (PR) protein expression and activity of the phenylpropanoid pathway. However, several identified transcripts remained unknown and may prove interesting candidates for further characterization.