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Oral: Plant Resistance


Cultivar-specific wheat miRNAs during stripe rust infection in Triticum aestivum
S. RAMACHANDRAN (1), N. Mueth (1), P. Zheng (1), S. Hulbert (1) (1) Washington State University, U.S.A.

Wheat represents approximately 30% of the world’s production of grain crops with more than 220 million cultivated hectares. Productivity at harvest is mainly governed by genetic composition and environmental factors influencing growth and development. Understanding the genetic factors that regulate these processes will help in developing varieties with better yield potential and disease resistance. MiRNAs are regulators of gene expression in eukaryotes that control myriad processes from development to abiotic and biotic stress responses. Using 12 small RNA libraries prepared from two wheat cultivars infected with stripe rust fungus (Puccinia striiformis), we identified 43 previously-known miRNAs, 50 novel variants of known miRNAs and 93 candidate novel miRNAs. Digital gene expression revealed 20 cultivar-specific miRNAs, 6 miRNAs differentially expressed between the two cultivars and 4 miRNAs responsive to stripe rust infection. These results were validated using RT-PCR and qRT-PCR. Using different target prediction algorithms, 69 wheat miRNAs were found to target fungal genes- a majority of which coded for small, secreted, cellular proteins. These results suggest a trans-kingdom regulation of gene expression potentially involved in the cultivar-specific resistance to stripe rust. Overall, this study contributes to the current repository of wheat miRNAs and provides novel information on the as yet uncharacterized roles for miRNAs in wheat host-pathogen interactions.