Disease and Insect Resistance in Cultivated Barley Accessions from the USDA National Small Grains Collection

tion database for the barley accessions is vital to increasing the utility of the collection in choosing parents for Cultivated barley (Hordeum vulgare subsp. vulgare L.) accessions germplasm enhancement, in genetic diversity assessfrom the USDA-ARS National Small Grains Collection (NSGC) have been tested systematically for the past 20 yr for disease and insect ments, and as baseline data for genomic research efforts. resistance. In this study, we analyzed the resistance to barley yellow Barley is grown worldwide across a wide diversity of dwarf (BYD), spot blotch (SB) caused by Cochliobolus sativus (Ito environments. It is more broadly adapted than any other and Kuribayashi) Drechs. ex Dastur, net blotch (NB) caused by Pyrecereal crop and is produced in many areas that are nophora teres f. teres Drechs., stripe rust (SR) caused by Puccinia unfavorable for production of other cereals (Poehlman, striiformis Westend. f. sp. hordei, and Russian wheat aphid (RWA), 1985). The NSGC has barley accessions from more than Diuraphis noxia (Mordvilko), with respect to (i) geographic origin of 90 countries, representing landraces, originally develresistant accessions, (ii) relationship to other NSGC descriptor data, oped by farmers and collected from either farmer fields and (iii) relationships among resistances. “Centers of concentration” or markets, and lines and cultivars developed by plant for certain resistances were identified: eastern Africa for several disscientists through hybridization. Few studies have been eases, western Turkey and the Caucasus for SR resistance, eastern Asia for adult plant resistance to NB, and south-central Asia for RWA made to relate disease and insect resistance in cultivated resistance. Stripe rust resistance was also associated with accessions barley accessions to geographic origin and agronomic originating from high altitude in eastern Africa (Ethiopia). Various characteristics. The limited information available indiassociations between resistances and grain descriptors, plant habit, cates that disease resistance can vary depending on geoand landrace status were also found. Forty-eight accessions showed graphic origin and can be associated with various agromultiple resistances on the basis of the field disease data and the nomic traits. For example, resistance to BYD disease RWA greenhouse data. Many of these resistant accessions were from was frequent in accessions from high elevation regions Ethiopia, and many were of unknown origin. Stripe rust testing in in Ethiopia (Schaller et al., 1963) and resistance was asCalifornia and Bolivia supported the conclusion that winter-habit acsociated with various agronomic traits (Qualset, 1975). cessions were more resistant to the disease than were spring-habit Disease and insect resistances are critical traits for the accessions. Information from this study will be used to guide future NSGC acquisition and evaluation efforts. stability and sustainability of barley production. Barley yellow dwarf is the most widely distributed and damaging virus disease of barley worldwide (D’Arcy, 1997). The disease is caused by a group of luteoviruses that T NSGC contains more than 25 000 accessions of are aphid-transmitted and yield losses under natural cultivated barley that have been acquired during infection are estimated at about 15%. Resistant cultivars the past 100 yr by scientists from the USDA and others are the best control measure for BYD. Net blotch is one interested in crop germplasm conservation and utilizaof the most widely distributed foliar diseases of barley. tion. National Small Grain Collection accessions continue It is most severe in temperate regions of high rainfall and to be acquired, maintained, and distributed as part of humidity, although epidemics have occurred in the low an effort to assure the availability of diverse germplasm rainfall areas of western Australia. Many countries have for use in developing productive, high-quality barley culreported an increased incidence of NB in the last several tivars. Upon request, accessions from the NSGC are prodecades, caused in part by the more common practice of vided free of cost to scientists worldwide. Passport and growing barley continuously in one field and with inevaluation data are found on the USDA-ARS Germplasm creased use of irrigation. Minimum tillage practices, which Resources Information Network (GRIN) at www.ars-grin. increase crop residue, also may contribute to an increase gov/npgs. Systematic gathering of descriptor data for the in NB because more inoculum is retained in the field. collection began in 1983, including evaluation of cultiYield losses due to NB can approach 100% in severely vated barley accessions for various agronomic, spike, affected fields of highly susceptible cultivars, but more seed, and quality traits as well as for resistance to importypical losses range from 10 to 40% (Steffenson, 1997). tant diseases and insects. Expanding the characterizaNet blotch can also reduce the quality of the grain as both kernel plumpness and malt extract yield can be J.M. Bonman and H.E. Bockelman, USDA-ARS, Small Grains and Potato Germplasm Research Unit, 1691 South 2700 West, Aberdeen, diminished in barley infected with the pathogen. Spot ID 83201; Lee F. Jackson, Dep. of Agronomy and Range Science, blotch is found in nearly every region where barley is Univ. of California, Davis, CA 95616; B.J. Steffenson, Dep. of Plant grown. However, it appears to cause significant losses Pathology, Univ. of Minnesota, St. Paul, MN 55018. Received 15 Sept. only in areas with a warm, humid climate and is rarely 2004. *Corresponding author ([email protected]). a problem in barley grown under semiarid conditions. Published in Crop Sci. 45:1271–1280 (2005). Spot blotch has been especially damaging in the upper Plant Genetic Resources Midwest region of the USA and in the central provinces doi:10.2135/cropsci2004.0546 of Canada. The severity of SB infection on barley can © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA vary greatly from year to year because the pathogen is 1271 Published online May 27, 2005