Transgenic Wheat Exhibits Enhanced Resistance to FHB

My program seeks to identify the mechanisms and essential genes for scab resistance and develop scab resistant wheat and barley germplasm through genetic engineering.

To identify the location of QTL (quantitative trait locus, which refers to the location of a gene(s) that affects a particular trait) for resistance to FHB, we have mapped new sources of FHB resistance in barley. The mapping work is a collaborative project with Drs. Kevin Smith and Ruth Dill-Macky.  We are also working in collaboration with Dr. Richard Zeyen, who is developing methods for faster, more efficient means of pretesting antifungal protein genes (AFP’s) that are of potential value in genetic engineering of cereals for resistance to FHB.

We have identified the location in the barley genome of genes for resistance to scab. Five populations have been studied and the location of the resistance genes appears to be consistent across populations. We have marked these locations with molecular markers, and the barley breeding project is now using these molecular markers to incorporate these regions carrying resistance into elite barley cultivars.

A gene discovery program is well underway to identify mechanisms and essential genes for FHB resistance in wheat and barley.  We worked with Dr. Olin Anderson’s laboratory (USDA-ARS, Albany, CA) to sequence 10,000 expressed sequence tags, or ESTs, which represent a snapshot of genes expressed in a given tissue and/or at a given developmental stage within the plant.  We also collaborated with Dr. Rod Wing of Clemson University to sequence 5,000 barley ESTs. The wheat and barley ESTs are providing the tools and information for understanding the interaction between small grains and F. graminearum.  In the future, we will use the genes in this resource for our transformation effort.

To further our understanding of genes involved in resistance, we conducted a computerized comparison of the genes expressed in common between the wheat and barley libraries prepared from F. graminearum-infected spikes.  Our intent is to identify genes expressed in common in two different plants infected with the same pathogen.

In addition, we compared our barley ESTs to 15,000 ESTs from three barley cDNA libraries prepared from barley leaves inoculated with Blumeria graminis (causal agent of powdery mildew). In this case, we are studying the genes that are expressed in common in the same plant infected by two different pathogens.  We have identified a set of rarely-expressed genes involved in plant-pathogen interactions that may play a role in resistance.  Currently, we are examining the expression of this select group of genes during F. graminearum infection. 

We are also establishing experiments that will provide information regarding the mechanisms and essential genes in wheat FHB resistance.

We have a large set of antifungal protein genes that are available for transformation into wheat, and have developed transgenic wheat with examples and combinations of these antifungal protein genes. We have conducted FHB screens on some of the transgenic lines. In general, the non-transgenic controls (Bobwhite and nontransformed siblings of the transgenic events) exhibited between 60-90% FHB severity, while the transgenic lines that exhibit enhanced resistance ranged from 25-45% FHB severity.  Thus, our data shows that we have developed transgenic wheat that exhibits enhanced resistance to FHB. 

Our results indicate that we have developed transgenic plants that carry a set of antifungal protein genes and that some of these lines exhibit reduced FHB severity.  Currently, we are increasing seed for the lines that are exhibiting enhanced resistance and we will screen these lines in the spring of 2003 and in field in the summer of 2003.

– Dr. Gary Muehlbauer, U of M molecular geneticist

Cereal Disease Lab Complements UM FHB Research

The USDA-ARS Cereal Disease Lab located at the U of M’s St. Paul campus complements FHB research conducted under the Minnesota Small Grains Initiative. The CDL, www.cdl.umn.edu , still focuses much of its attention on rust research, including the monitoring of rust infections in small grains across the nation.

However, about one-third of the CDL’s research efforts now are focused on FHB.  That includes research by Bill Bushnell, conducted cooperatively with Ron Skadsen, USDA-ARS Barley and Malt Lab, Madison, Wis.  Their research has resulted in a method that greatly improves the ability to trace development of the scab fungus in infected head tissues, and help determine the principal pathways of infection in head tissues of wheat and barley.

Corby Kistler, CDL research geneticist, is studying genetic variations of the scab pathogen nationwide, which will lead to a better understanding of how Fusarium may infect a wheat field in Minnesota as opposed to a wheat field in Michigan or Arkansas, for example. 

Three crop scientists at the CDL devote at least a portion of their research to FHB, according to Martin Carson, CDL research leader.

On-Farm Trials and Outreach

Outreach information has been instrumental in helping producers manage FHB and other production problems, and playing a key role in this effort is Dr. Jochum Wiersma, small grains specialist based at the NWROC, Crookston. Wiersma works with extension educators in the region to disseminate information, conducts on-farm cropping trials, answers producer questions and visits fields across western Minnesota for diagnostic help.  Wiersma provides educational small grains production information in meetings across western Minnesota, and is a regular contributor to Prairie Grains.