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. This cell sacrifice can cause very small, often microscopic, spots or lesions on the plant.

But up until now it's been difficult to understand how the plant regulates this "spotty" defense mechanism because the response is so quick and localized.

Researchers at North Carolina State University have 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 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,  says Dr. Peter Balint-Kurti, the paper's corresponding author and a U.S. Department of Agriculture (USDA) professor who works in NC State's plant pathology and crop science departments.

To arrive at the finding, 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 says. "This mutation causes a corn plant to inappropriately trigger this hypersensitive defense response, causing spots on the corn plant as well as stunted growth."

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. Balint-Kurti said the top candidates made sense, as they mostly appear to be linked to defense or disease resistance.

"All of the processes associated with the top candidate genes have been previously associated with HR," Balint-Kurti said. "Hopefully this work provides an opening to really characterize this important defense response and learn more about it in other plants."

USDA plant geneticist and breeder Jim Holland co-authored the paper along with first authors Bode Olukolu and Guan Feng Wang, who are post-doctoral researchers at NC State. Vijay Vontimitta, a post-doctoral researcher at Purdue working in a group headed by Guri Johal, is also a first author.

The research was funded by USDA, the National Science Foundation, NC State and Purdue University.

- kulikowski -

Note: An abstract of the paper follows.

"Multivariate Analysis of Maize Disease Resistance Suggests a Pleiotropic Genetic Basis and Implicates a Glutathione S-transferase Gene"

Authors: Bode A. Olukolu, Guan Feng Wang, Adisu Negeri, Dahlia Nielsen, James Holland and Peter Balint-Kurti, North Carolina State University; Vijay Vontimitta, Bala Venkata, Sandeep Marla, Jiabing Ji, Emma Gachomo, Kevin Chu and Gurmukh Johal, Purdue University; Jacqueline Benson, Rebecca Nelson and Peter Bradbury, Cornell University

Published: Aug. 28, 2014, in PLOS Genetics

DOI: 10.1371/journal.pgen.1004562

Abstract: Much remains unknown of molecular events controlling the plant hypersensitive defense response (HR), a rapid localized cell death that limits pathogen spread and is mediated by resistance (R-) genes. Genetic control of the HR is hard to quantify due to its microscopic and rapid nature. Natural modifiers of the ectopic HR phenotype induced by an aberrant auto-active R-gene (Rp1-D21), were mapped in a population of 3,381 recombinant inbred lines from the maize nested association mapping population. Joint linkage analysis was conducted to identify 32 additive but no epistatic quantitative trait loci (QTL) using a linkage map based on more than 7000 single nucleotide polymorphisms (SNPs). Genome-wide association (GWA) analysis of 26.5 million SNPs was conducted after adjusting for background QTL. GWA identified associated SNPs that colocalized with 44 candidate genes. Thirty-six of these genes colocalized within 23 of the 32 QTL identified by joint linkage analysis. The candidate genes included genes predicted to be in involved programmed cell death, defense response, ubiquitination, redox homeostasis, autophagy, calcium signalling, lignin biosynthesis and cell wall modification. Twelve of the candidate genes showed significant differential expression between isogenic lines differing for the presence of Rp1-D21. Low but significant correlations between HR-related traits and several previously-measured disease resistance traits suggested that the genetic control of these traits was substantially, though not entirely, independent. This study provides the first system-wide analysis of natural variation that modulates the HR response in plants.

Washington, D.C. - Rep. Bruce Braley (IA-01) today released the following statement in honor of the 13th anniversary of the September 11, 2001 terrorist attacks on the United States.

"It is clear that the breadth and scope of the unconscionable acts of terror visited upon the United States thirteen years ago remain impossible to measure. The effect is most profound on those who lost loved ones that day?or those who subsequently lost a loved ones during our military missions to combat terrorist threats across the globe?and my thoughts and prayers are with all of them today. While these attacks occurred over a decade ago, the underlying question of how America should respond to terrorist threats throughout the world remains one of our toughest challenges. I will continue to take a thoughtful and measured approach to combating these threats and ensure that the safety of Americans and our interests remain my top priority."

Washington, D.C. - Congressman Dave Loebsack released the following statement this evening following the President's speech on the Islamic State. As a member of the House Armed Services Committee, Loebsack has received briefings regarding the ongoing situation.

"Without question, the security situation in Iraq and Syria and the escalating threat from ISIS is a national security concern for the United States. The challenge with assessing ISIS is not whether these are evil people, because they have clearly proven they are. We have known that for a long time. I agree with the President that we must not put troops back in Iraq, but targeted air strikes may be necessary to degrade and defeat ISIS. We must do everything we can to protect the American people and our interests at home and abroad. Those who pose a real threat to Americans must know, there is no hiding from America's strength.

"The challenge that remains is whether or not certain military actions will create long-term, unintended consequences. Our foreign policy cannot be bomb first, ask questions later - that is what got us into this situation in the first place. Our allies around the world, and specifically in the region, must share this burden and work together to bolster political and economic conditions in Iraq and Syria. We cannot overcome centuries of sectarian strife with bombs alone. Ultimately the governments in Iraq and Syria must take responsibility for their own security."

WEST DES MOINES, Iowa (Sept. 10, 2014) ? Hy-Vee, Inc., the Iowa Department of Public Health (IDPH) and the Governor's Advisory Council on Brain Injuries have partnered to help educate Iowa's elderly about ways they can prevent falls and injury during National Falls Prevention Awareness Month in September.

The seventh annual Falls Prevention Awareness Day will be observed on Sept. 23, the first day of fall. This year's theme, Strong Today, Falls Free® Tomorrow, seeks to raise awareness about how to prevent fall-related injuries among older adults. Nearly 500,000 people over the age of 65 live in Iowa.

Hy-Vee, IDPH and the Governor's Advisory Council on Brain Injuries hope to keep Iowa's older population strong and falls-free by providing education and resources through several avenues ? pharmacies, websites, social media and a Sept. 17 webinar ? during the awareness month.

In September, when senior citizens fulfill their prescriptions at a Hy-Vee Pharmacy in Iowa, they will see educational information in their prescription bags.

"Our pharmacy staff often witness and help treat the aftermath of a fall, but this initiative enables us to bring awareness to the role we can play in prevention," said Andy McCann, executive vice president and chief health officer of Hy-Vee. "We encourage our customers to review their prescription and non-prescription medications with us, as this is one of the main preventive measures our elderly can take."

Falls are the leading cause of both fatal and nonfatal injuries for people 65 years of age and over, according to the National Council on Aging (NCOA). Every 14 seconds, an older adult is seen in an emergency department for a fall-related injury. And the chances of falling and of being seriously injured in a fall increase with age, the NCOA's website says.

"Older Iowans in our communities had 29,590 fall-related emergency department visits and hospitalizations in 2012. These fall-related injuries resulted in 429 fatalities and approximately $135 million in hospitalization charges," said Maggie Ferguson, IDPH brain injury and disability program manager. "We can change this by bringing greater attention to the many preventive measures that can be easily employed to keep our seniors safe."

Studies show that a combination of interventions can significantly reduce falls among older adults. Falls Prevention Awareness Month promotional materials will encourage Iowa's elderly adults to take the following steps:

• Review all their prescription and non-prescription medicines with their doctor and pharmacist.
• Talk to their health care provider about their risk of falling.
• Have their vision checked at least once a year.
• Talk to their family about their concerns.
• Exercise to improve their strength and balance.
• Make their home safer by removing things they can trip over.

"We thank the Iowa Department of Public Health and Hy-Vee for helping us to bring awareness to this issue. I have personally witnessed how injuries resulting from a fall can steal the quality of life from seniors and their families," said W. Dave Johnson, a member of the Governor's Advisory Council on Brain Injuries.

On Sept. 17 at 11 a.m., the Iowa Falls Prevention Coalition will host a webinar titled "Aging, Fall Risk and Prevention Through Exercise." To register for the webinar, visit https://www1.gotomeeting.com/register/760561400.

For more information about falls prevention, visit a local Hy-Vee Pharmacy; the IDPH Falls Prevention website at www.idph.state.ia.us/FallPrevention; or the NCOA website at www.ncoa.org/improve-health/falls-prevention.