Open AccessMetabolic constraints on Magnaporthe biotrophy: loss of de novo asparagine biosynthesis aborts invasive hyphal growth in the first infected rice cell
Author(s) -
Margarita Marroquin-Guzman,
Juliana Krotz,
Harriet Appeah,
Richard A. Wilson
Publication year - 2018
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.352
H-Index - 35
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/mic.0.000713
Subject(s) - asparagine , asparagine synthetase , magnaporthe , appressorium , biology , glutamine , mutant , biosynthesis , brachypodium distachyon , hypha , fungus , pyricularia , microbiology and biotechnology , biochemistry , amino acid , oryza sativa , enzyme , magnaporthe grisea , botany , gene , genome
The blast fungus Magnaporthe oryzae devastates global rice yields and is an emerging threat to wheat. Determining the metabolic strategies underlying M. oryzae growth in host cells could lead to the development of new plant protection approaches against blast. Here, we targeted asparagine synthetase (encoded by ASN1), which is required for the terminal step in asparagine production from aspartate and glutamine, the sole pathway to de novo asparagine biosynthesis in M. oryzae. Consequently, the Δasn1 mutant strains could not grow on minimal media without asparagine supplementation. Spores harvested from supplemented plates could form appressoria and penetrate rice leaf surfaces, but biotrophic growth was aborted and the Δasn1 strains were nonpathogenic. This work provides strong genetic evidence that de novo asparagine biosynthesis, and not acquisition from the host, is a critical and potentially exploitable metabolic strategy employed by M. oryzae in order to successfully colonize rice cells.