Into the Wild: FHB Resistance Identified in Wild Barley Accessions from Israel

Over the past decade, Brian Steffenson’s group at the University of Minnesota has screened over 25,000 cultivated barley accessions in the field for resistance to Fusarium head blight (FHB).  From this work, less than 1% of the accessions were found to have useful levels of resistance for breeding purposes. Still, several of these identified resistance sources have been used in Midwest barley breeding programs, with releases of cultivars with enhanced FHB resistance anticipated in the next several years. 

Brian Steffenson assessing the resistance of wild barley in a Fusarium head blight nursery at Zhejiang University in Hangzhou, China.

In addition to cultivated barley, an alternative source of genetic diversity for disease resistance is wild barley: Hordeum vulgare subsp. spontaneum.  Wild barley is the progenitor of cultivated barley and is native to the Fertile Crescent. However, it can be found across a much larger region stretching from North Africa in the west to Pakistan in the east. Many diverse sources of resistance to various diseases (e.g. leaf rust, stem rust, net blotch, spot blotch and Septoria) have been discovered in wild barley.  Yet, this important genepool for cultivated barley improvement has not been systematically evaluated for reaction to FHB.  The primary objective of our study is to go “into the wild” and seek sources of FHB resistance in wild barley.  Over 2,000 wild barley accessions from ecogeographically diverse regions of the world were evaluated for FHB resistance in our off-season screening nursery in China over the past several years.  These accessions were obtained from various gene banks including the USDA National Small Grains Collection (NSGC) in Aberdeen, ID; N. I. Vavilov All-Russian Scientific Research Institute of Plant Industry (VIR) in St. Petersburg, Russia; International Center for Agriculture in the Dry Areas (ICARDA) in Aleppo, Syria; and Institute for Cereal Crops Improvement (ICCI) in Tel Aviv, Israel.  A high level of diversity was observed in response to FHB in this wild barley germplasm; unfortunately, like cultivated barley, the percentage of resistant accessions identified was very low (i.e. less than 0.5 %).  Yet from these evaluations, we discovered a group of wild barley accessions from Israel that possess a moderate level of resistance.  These resistant accessions originate from the Jordan River region of Israel and have a distinct morphology (a petite spike) from other wild barley types.  In replicated tests conducted in Hangzhou, China in 2005-06 and 2006-07, the accession PI 466423 exhibited FHB severities that were slightly lower than Chevron (1.4 vs. 1.7 on a 1 to 5 scale where 5 is most susceptible), the six-rowed standard of resistance.  Being a unique wild barley accession, PI 466423 likely possesses alleles for FHB resistance that have not yet been exploited in breeding programs.

Wild barley accession PI 466423 (left) possesses a moderate level of resistance to Fusarium head blight compared to other wild barley accessions (right).

Our ultimate goal is to reduce the losses caused by FHB, including quality discounts due to DON contamination.  This can be best achieved by developing barley cultivars with the highest level of resistance possible. Our next objectives for this project are to determine the number and chromosomal position of FHB resistance loci in PI 466423 and transfer them as quickly as possible into cultivated barley.  The information generated from this study will lead to the development of malting barley cultivars with FHB resistance and low DON accumulation.  This, in turn, will minimize the threat of FHB and associated mycotoxins for producers, processors, and consumers.  

-- Brian Steffenson, Department of Plant Pathology, University of Minnesota