Protein phosphatase 2A regulatory subunits perform distinct functional roles in the maize pathogen Fusarium verticillioides. (3rd March 2013)

• Record Type: Journal Article
• Authors: Shin, Joon‐Hee; Kim, Jung‐Eun; Malapi‐Wight, Martha; Choi, Yoon‐E.; Shaw, Brian D.; Shim, Won‐Bo
• Is Part Of: Molecular plant pathology. Volume 14:Number 5(2013:Jun.)
• Page Start: 518
• Page End: 529
• Publication Date: 2013-03-03
• Subjects: Plant diseases -- Molecular aspects -- Periodicals; Plant-pathogen relationships -- Molecular aspects -- Periodicals; 571.936
• DOI: 10.1111/mpp.12023
• Languages: English
• ISSNs: 1464-6722

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p> <italic>Fusarium verticillioides</italic> is a pathogen of maize causing ear rot and stalk rot. The fungus also produces fumonisins, a group of mycotoxins linked to disorders in animals and humans. A cluster of genes, designated <italic>FUM</italic> genes, plays a key role in the synthesis of fumonisins. However, our understanding of the regulatory mechanism of fumonisin biosynthesis is still incomplete. We have demonstrated previously that Cpp1, a protein phosphatase type 2A (PP2A) catalytic subunit, negatively regulates fumonisin production and is involved in cell shape maintenance. In general, three PP2A subunits, structural A, regulatory B and catalytic C, make up a heterotrimer complex to perform regulatory functions. Significantly, we identified two PP2A regulatory subunits in the <italic>F. verticillioides</italic> genome, Ppr1 and Ppr2, which are homologous to <italic>Saccharomyces cerevisiae</italic> Cdc55 and Rts1, respectively. In this study, we hypothesized that Ppr1 and Ppr2 are involved in the regulation of fumonisin biosynthesis and/or cell development in <italic>F. verticillioides</italic>, and generated a series of mutants to determine the functional role of Ppr1 and Ppr2. The <italic>PPR1</italic> deletion strain (Δppr1) resulted in drastic growth defects, but increased microconidia production. The <italic>PPR2</italic> deletion mutant strain (Δppr2) showed elevated fumonisin production, similar to the Δcpp1 strain. Germinating Δppr1 conidia formed abnormally swollen cells with a central septation site, whereas Δppr2 showed early hyphal branching during conidia germination. A kernel rot assay showed that the mutants were slow to colonize kernels, but this is probably a result of growth defects rather than a virulence defect. Results from this study suggest that two PP2A regulatory subunits in <italic>F. verticillioides</italic> carry out distinct roles in the regulation of fumonisin biosynthesis and fungal development.</p> </abstract>