44 genes in corn defense response identified

When corn plants come under attack from a pathogen, they sometimes respond by killing their own cells near the site of the attack, committing "cell suicide" to thwart further damage from the attacker, scientists say.
This cell sacrifice can cause very small, often microscopic, spots or lesions on the plant, researchers said.
Until now it's been difficult to understand how the plant regulates this "spotty" defense mechanism because the response is so quick and localised.
Researchers at North Carolina State University have now identified a number of candidate genes and cellular processes that appear to control this so-called hypersensitive defense response (HR) in corn.

The findings, which appear in the journal PLOS Genetics, could help researchers build better defense responses in corn and other plants; HR is thought to occur in all higher-order plants, including all trees and crop plants, and is normally a tightly regulated response.
The 44 candidate genes appear to be involved in defense response, programmed cell death, cell wall modification and a few other responses linked to resisting attack, said Dr Peter Balint-Kurti, the paper's corresponding author and a US Department of Agriculture (USDA) professor who works in NC State's plant pathology and crop science departments.

The NC State researchers joined researchers from Purdue University in examining more than 3,300 maize plants that contained a similar mutation: They all had exaggerated HR because one particular resistance gene, Rp1-D21, doesn't turn off.

"It's similar to a human having an auto-immune response that never stops," Balint-Kurti said.
"This mutation causes a corn plant to inappropriately trigger this hypersensitive defense response, causing spots on the corn plant as well as stunted growth," he said.
The researchers examined the entire corn gene blueprint - some 26.5 million points in the 2 to 3 billion base pair genome - to find the genes most closely associated with HR.