Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 Dec 14;107(50):21896-901.
doi: 10.1073/pnas.1003619107. Epub 2010 Nov 22.

A Regulon Conserved in Monocot and Dicot Plants Defines a Functional Module in Antifungal Plant Immunity

Affiliations
Free PMC article

A Regulon Conserved in Monocot and Dicot Plants Defines a Functional Module in Antifungal Plant Immunity

Matt Humphry et al. Proc Natl Acad Sci U S A. .
Free PMC article

Abstract

At least two components that modulate plant resistance against the fungal powdery mildew disease are ancient and have been conserved since the time of the monocot-dicot split (≈ 200 Mya). These components are the seven transmembrane domain containing MLO/MLO2 protein and the syntaxin ROR2/PEN1, which act antagonistically and have been identified in the monocot barley (Hordeum vulgare) and the dicot Arabidopsis thaliana, respectively. Additionally, syntaxin-interacting N-ethylmaleimide sensitive factor adaptor protein receptor proteins (VAMP721/722 and SNAP33/34) as well as a myrosinase (PEN2) and an ABC transporter (PEN3) contribute to antifungal resistance in both barley and/or Arabidopsis. Here, we show that these genetically defined defense components share a similar set of coexpressed genes in the two plant species, comprising a statistically significant overrepresentation of gene products involved in regulation of transcription, posttranslational modification, and signaling. Most of the coexpressed Arabidopsis genes possess a common cis-regulatory element that may dictate their coordinated expression. We exploited gene coexpression to uncover numerous components in Arabidopsis involved in antifungal defense. Together, our data provide evidence for an evolutionarily conserved regulon composed of core components and clade/species-specific innovations that functions as a module in plant innate immunity.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Gene expression governed by a unique cis element in Arabidopsis is light- and pathogen-responsive. Histochemical analysis of transgenic Arabidopsis plants expressing a promoter-GUS construct containing a tandem repeat of a unique cis element (see text). (A) Overrepresented cis element identified by MEME and MAST analysis. (B) Four-week-old T3 plants soil-grown under short (Left) and long (Right) days. (C) Unchallenged, G. orontii, and E. pisi-inoculated (left to right) rosette leaves of 4-wk-old short-day-grown T3 plants at 3 d after inoculation. (D) Wounded (forceps mark) rosette leaf of 4-wk-old short-day-grown T3 plant. Similar expression patterns were observed in four independent transgenic lines. (E) Results of quantitative GUS assay on multiple T2 plants (4–9 per line) of four different transgenic lines upon inoculation with Bgh (at 3 d after inoculation). Values of each line were normalized to the uninoculated control (set as 1); error bars represent the SEM. Asterisks indicate a significant difference from the uninoculated control (*P ≤ 0.05; **P ≤ 0.01; Student's t test). Similar results were obtained in two independent experiments.
Fig. 2.
Fig. 2.
Mutants with insertions in unique coexpressed genes exhibit enhanced disease symptoms to a range of pathogens with diverse lifestyles. (A) Representative macroscopic phenotypes of Col-0 and selected insertion lines 10 d after inoculation with G. orontii. (B) Quantitative analysis of host cell entry of E. pisi on selected lines determined at 3 d after inoculation. Results represent mean ± SD of at least five leaves per genotype. (C) Quantification of disease symptoms 6 days after inoculation with B. cinerea (Materials and Methods). Results represent mean ± SD of three independent samples per genotype. Comparable results were obtained in at least three independent experiments. For all data, asterisks indicate a significant difference from Col-0 (*P ≤ 0.05; **P ≤ 0.01; Student's t test).
Fig. 3.
Fig. 3.
Mutants with insertions in coexpressed genes exhibit perturbed levels of glucosinolates and glucosinolate metabolites. (A) Accumulation of indicated selected secondary metabolites (nmol/g of fresh tissue weight) in indicated Arabidopsis genotypes without (open bars) or 16 h after inoculation with E. pisi conidiospores (filled bars). Results represent mean ± SD of three independent plants per genotype. Asterisks indicate a significant difference from respective Col-0 sample (*P ≤ 0.05; **P ≤ 0.01), and hash marks indicate a significant difference between inoculated and uninoculated plants of particular genotypes (#P ≤ 0.05; ##P ≤ 0.01; Student's t test). Comparable results were obtained in at least three independent experiments. (B) Schematic diagram of indole glucosinolate biosynthesis, showing locations of genes previously identified and unique genes identified in this study. Biosynthetic enzymes are highlighted by boxes; proteins with other activities by ovals. Diagram adapted from ref. .

Similar articles

See all similar articles

Cited by 40 articles

See all "Cited by" articles

Publication types

MeSH terms

LinkOut - more resources

Feedback