title: Functional contribution of chorismate synthase, anthranilate synthase, and chorismate mutase to penetration resistance in barley-powdery mildew interactions.
abstract: Plant processes resulting from primary or secondary metabolism have been hypothesized to contribute to defense against microbial attack. Barley chorismate synthase (HvCS), anthranilate synthase alpha subunit 2 (HvASa2), and chorismate mutase 1 (HvCM1) occupy pivotal branch points downstream of the shikimate pathway leading to the synthesis of aromatic amino acids. Here, we provide functional evidence that these genes contribute to penetration resistance to Blumeria graminis f. sp. hordei, the causal agent of powdery mildew disease. Single-cell transient-induced gene silencing of HvCS and HvCM1 in mildew resistance locus a (Mla) compromised cells resulted in increased susceptibility. Correspondingly, overexpression of HvCS, HvASa2, and HvCM1 in lines carrying mildew resistance locus o (Mlo), a negative regulator of penetration resistance, significantly decreased susceptibility. Barley stripe mosaic virus-induced gene silencing of HvCS, HvASa2, and HvCM1 significantly increased B. graminis f. sp. hordei penetration into epidermal cells, followed by formation of haustoria and secondary hyphae. However, sporulation of B. graminis f. sp. hordei was not detected on the silenced host plants up to 3 weeks after inoculation. Taken together, these results establish a previously unrecognized role for the influence of HvCS, HvASa2, and HvCM1 on penetration resistance and on the rate of B. graminis f. sp. hordei development in Mla-mediated, barley-powdery mildew interactions.
authors.affiliation: Interdepartmental Genetics Program, Department of Plant Pathology and Center for Plant Responses to Environmental Stresses, Iowa State University, Ames 50011-1020, USA.
authors.forename: Pingsha
authors.initials: P
authors.lastname: Hu
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Roger P
authors.initials: RP
authors.lastname: Wise
mesh_terms: D000878:Anthranilate Synthase / Q000378:metabolism*; D002826:Chorismate Mutase / Q000378:metabolism*; D005658:Fungi / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D020868:Gene Silencing; D020022:Genetic Predisposition to Disease; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology*; D008969:Molecular Sequence Data; D019761:Phosphorus-Oxygen Lyases / Q000378:metabolism*; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010942:Plant Viruses; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: C104922:MLO protein, Hordeum vulgare; D010940:Plant Proteins; D012333:RNA, Messenger; D000878:Anthranilate Synthase; C019895:chorismate synthase; D019761:Phosphorus-Oxygen Lyases; D002826:Chorismate Mutase