Maize Tissue Necrosis

Maize Lethal Necrosis (MLN) is the most specific disease resulting from a synergistic infection by Maize Chlorotic Mottle Virus (MCMV) and members of the Potyviridae group (SCMV, MDMV, etc.). Characteristic symptoms of the disease include systemic chlorotic mosaic, progressive necrosis, stunting, and organ deformation, leading to plant death before maturity.

In other cases, tissue necrosis in maize acts as a diagnostic symptom of fungal pathologies. Necrosis of the mesocotyl, caused by species of the genus Fusarium, Rhizoctonia, or Pythium, is accompanied by tissue rot and suppression of seedling growth. Nigrospora cob rot causes shredding of the cob core, while infection by the Phyllachora maydis and Monographella maydis complex results in the formation of 'fish-eye' necrotic spots.

Breeding for resistance to MLN relies on the use of quantitative trait loci (QTL) and marker-assisted selection to control both viral components. There is no unified nomenclature for specific resistance genes; modern methods include genomic mapping and editing of regulatory genome regions to enhance the complex tolerance of hybrids.