User:Mikethurston1990/Magnaporthe grisea

Genetics
Whole-genome sequences were just becoming possible, and being made available, in 2003.

A mitogen-activated protein kinase (MAPK) called pmk1 is genetically close to one necessary for mating and cell morphology in yeasts, FUS3/KSS1. Defective mutant yeast are somewhat or entirely restored in mating function if they are given a copy of pmk1. It was therefore assumed that this must only be a mating and development gene in M. grisea, however it turns out to be both vital to the female mating process and in appressorium function and pathogenicity as a whole.

Because signal links between MAPKs and cyclic adenosine monophosphates were shown to be required for mating in several other models, including Ustilago maydis and several others, this was assumed to be true for M. grisea, and yet that was then shown to be unnecessary in this model. This demonstrates significant variety in cellular function within fungi.

The transaminase alanine: glyoxylate aminotransferase 1 (AGT1) has been shown to be crucial to the pathogenicity of M. grisea through its maintenance of redox homeostasis in peroxisomes. Lipids transported to the appressoria during host penetration are degraded within a large central vacuole, a process that produces fatty acids. β-Oxidation of fatty acids is an energy producing process that generates Acetyl-CoA and the reduced molecules FADH2 and NADH, which must be oxidized to NAD+ and FADH to maintain redox homeostasis in appressoria. AGT1 promotes lactate fermentation, oxidizing NADH/FADH2 in the process.

M. grisea mutants lacking the AGT1 gene were observed to be nonpathogenic through their inability to penetrate host surface membranes. This indicates the possibility of impaired lipid utilization in M. grisea appressoria in the absence of the AGT1 gene.