AUTHOR=Majumdar Rajtilak , Rajasekaran Kanniah , Sickler Christine , Lebar Matthew , Musungu Bryan M. , Fakhoury Ahmad M. , Payne Gary A. , Geisler Matt , Carter-Wientjes Carol , Wei Qijian , Bhatnagar Deepak , Cary Jeffrey W. 

TITLE=The Pathogenesis-Related Maize Seed (PRms) Gene Plays a Role in Resistance to Aspergillus flavus Infection and Aflatoxin Contamination

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01758

DOI=10.3389/fpls.2017.01758

ISSN=1664-462X

ABSTRACT=<p><italic>Aspergillus flavus</italic> is an opportunistic plant pathogen that colonizes and produces the toxic and carcinogenic secondary metabolites, aflatoxins, in oil-rich crops such as maize (<italic>Zea mays ssp. mays</italic> L.). Pathogenesis-related (PR) proteins serve as an important defense mechanism against invading pathogens by conferring systemic acquired resistance in plants. Among these, production of the PR maize seed protein, <italic>ZmPRms</italic> (AC205274.3_FG001), has been speculated to be involved in resistance to infection by <italic>A. flavus</italic> and other pathogens. To better understand the relative contribution of <italic>ZmPRms</italic> to <italic>A. flavus</italic> resistance and aflatoxin production, a seed-specific RNA interference (RNAi)-based gene silencing approach was used to develop transgenic maize lines expressing hairpin RNAs to target <italic>ZmPRms</italic>. Downregulation of <italic>ZmPRms</italic> in transgenic kernels resulted in a ∼250–350% increase in <italic>A. flavus</italic> infection accompanied by a ∼4.5–7.5-fold higher accumulation of aflatoxins than control plants. Gene co-expression network analysis of RNA-seq data during the <italic>A. flavus</italic>-maize interaction identified <italic>ZmPRms</italic> as a network hub possibly responsible for regulating several downstream candidate genes associated with disease resistance and other biochemical functions. Expression analysis of these candidate genes in the <italic>ZmPRms</italic>–RNAi lines demonstrated downregulation (vs. control) of a majority of these <italic>ZmPRms</italic>-regulated genes during <italic>A. flavus</italic> infection. These results are consistent with a key role of <italic>ZmPRms</italic> in resistance to <italic>A. flavus</italic> infection and aflatoxin accumulation in maize kernels.</p>