Plant & Animal Genomes XVII Conference

January 10-14, 2009
Town & Country Convention Center
San Diego, CA

Blufensin1 Negatively Regulates Basal Defense In Response To Barley Powdery Mildew

Yan Meng¹ , Matthew J. Moscou^1,2 , Roger P. Wise^1,2,3

¹  Department of Plant Pathology and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames, IA 50011-1020 USA

²  Bioinformatics and Computational Biology Graduate Program, Iowa State University, Ames, IA 50011-1020 USA

³  Corn Insects and Crop Genetics Research, USDA-ARS, Iowa State University, Ames, IA 50011-1020 USA

Plants have evolved complex regulatory mechanisms to control the defense response against microbial attack. Both temporal and spatial gene expression are tightly regulated in response to pathogen ingress, modulating both positive and negative control of defense. BLUFENSIN1 (BLN1), a small peptide belonging to a novel family of defensin-like proteins in barley (Hordeum vulgare L.), is highly induced by attack from the obligate biotrophic fungus, Blumeria graminis f. sp. hordei (Bgh) , casual agent of powdery mildew disease. Computational interrogation of the Bln1 gene family determined that members reside solely in the BEP clade of the Poaceae family, specifically, barley, rice and wheat. Barley stripe mosaic virus induced gene-silencing (BSMV-VIGS) of Bln1 enhanced plant resistance in compatible interactions, regardless of the presence or absence of functional Mla CC-NBS-LRR alleles, indicating BLN1 can function in an R-gene independent manner. Likewise, transient overexpression of Bln1 significantly increases accessibility towards virulent Bgh. Moreover, silencing in plants harboring the Mlo susceptibility factor decreased accessibility to Bgh, suggesting BLN1 functions in parallel with or upstream of MLO to modulate penetration resistance. Collectively, these data establish a previously unrecognized role for Bln1 as a negative regulator of barley innate immunity to Bgh.