Fusarium Head Blight Reaction of Langdon Durum-Triticum dicoccoides Chromosome Substitution Lines

since the early 1980s (McMullen et al., 1997; Wilcoxson et al., 1988; Windels, 2000). Fusarium head blight (FHB), caused by Fusarium graminearum Management practices such as crop rotation have Schwabe, is a serious disease problem on durum wheat (Triticum been ineffective in limiting the disease. Most researchers turgidum L. var. durum ) in the USA. To date, the resistance to FHB available in hexaploid wheat (T. aestivum L.) sources has not been agree that incorporation of resistance is the best longtransferred successfully to tetraploid durum. In the 1980s, USDA term answer to FHB (Meidaner, 1997). Sources of resisgeneticist L.R. Joppa produced a set of disomic lines [LDN(DIC)] tance to FHB are available in hexaploid wheat (Mesterderived from wild emmer (T. turgidum L. var. dicoccoides ). Each hazy, 1995); however, transfer of that resistance from line had a different pair of chromosomes from T. dicoccoides substihexaploid wheat to durum has not been reported. Dututed for the corresponding ‘Langdon’ durum chromosomes. The purrum wheat cultivars differ in their response to FHB pose of this study was to determine if any of the LDN(DIC) lines from moderately to highly susceptible (McMullen et al., showed useful levels of resistance to FHB. We tested these lines for 1994; Stack, 1988; Stack and Elias, 1995–2000, unpubFHB response by inoculation with F. graminearum in the greenhouse. lished). Inoculation was accomplished via the single spikelet method, in which The greatest progress to date in identification of resisa droplet of conidiospore suspension is placed into one spikelet per spike followed by mist–high humidity for 3 d to establish infection. tance to FHB has been with resistance expressed as After 21 d, spikes were scored for extent of FHB symptoms and the limitation of the spread of infection within the spike average disease severity of the lines compared. A low disease severity (Wang and Miller, 1988). This phenotypic expression score in this test indicated the presence of resistance to FHB in that has been termed “Type II” resistance in the literature line. Each test was replicated and the tests were done five times. In (Meidaner, 1997; Mesterhazy, 1995). Molecular markers each test, some lines differed significantly. One line, LDN(DIC-3A), for quantitative trait loci (QTL) associated with Type was consistently less susceptible and another line, LDN(DIC-2A), II resistance have been identified in hexaploid wheat was consistently more susceptible than the parent Langdon durum, (Anderson et al., 2001; Waldron et al., 1999). which itself showed an intermediate FHB reaction. Several other Triticum turgidum L. var. dicoccoides (TDIC) posLDN(DIC) lines showed a trend either for increased or reduced sesses many interesting traits, including resistance to susceptibility to FHB. Since each line differs by a single chromosome pair, the results suggest that genes affecting FHB resistance are present stem rust (Puccinia graminis Pers.) (Miller et al., 1998), on several different T. dicoccoides or Langdon durum chromosomes. resistance to stripe rust (P. striiformis Pers.) (Reinhold et al., 1983), resistance to FHB (Miller et al., 1998), and grain quality factors (Joppa et al., 1991). A set of disomic chromosome substitution lines from TDIC in the backF head blight is a plant disease that adversely affects wheat and other small grains ground of Langdon durum had been developed as described by Joppa and Williams (1988) using the TDIC throughout the world. In North America, FHB is caused mainly by Fusarium graminearum Schwabe [sexual line FA-15-3 (“Israel A”). A gene for high grain protein concentration in this population has been studied stage: Gibberella zeae (Schw.) Petch], with occasional involvement of other Fusarium species (McMullen et (Joppa and Cantrell, 1990; Steiger et al., 1996) and mapped (Joppa et al., 1997). These lines have also been al., 1997; Stack and McMullen, 1985; Wong et al., 1992). Outbreaks of FHB on wheat are unpredictable and evaluated for agronomic traits and grain quality (Cantrell and Joppa, 1991; Elias et al., 1996; Joppa et al., highly dependent on weather conditions during and just following anthesis, when plants are at the most suscepti1991). In a search for potentially useful sources of resistance ble stage (Sutton, 1982). On spring wheat (Triticum aestivum L.) and durum (T. turgidum L. var. durum) in to FHB in durum, we tested FHB reactions of several hundred durum lines and accessions (Stack and Elias, the northern Great Plains region of North America, the epidemics of 1993, 1994, and 1997 were very severe, 1994, unpublished). In one such screening test in 1994, we included several of the disomic chromosome substiwith more localized losses occurring in other years between 1995 and 2000. Previous outbreaks, on a more tution lines developed for high grain protein concentration (Joppa and Williams, 1988). limited scale, had occurred sporadically in the region On the basis of results from those preliminary tests, we decided to examine the entire set of the LDN(DIC) R.W. Stack, Dep. of Plant Pathology, North Dakota State Univ., disomic chromosome substitution lines for reaction to Fargo, ND 58105; E.M. Elias, Dep. of Plant Sciences, North Dakota FHB. The purpose of this study was to determine if State Univ., Fargo, ND 58105; J. Mitchell Fetch, Agriculture and Agriany of the LDN(DIC) lines showed useful levels of Foods Canada, Winnipeg, MB, R3T 2M9 Canada; J.D. Miller, L.R. Joppa, USDA-ARS, Northern Crops Research Laboratory, Fargo, Abbreviations: FDK, Fusarium damaged kernels; FHB: Fusarium ND 58105. Received 23 March 2001. *Corresponding author (rstack@ head blight; LDN(DIC), Langdon durumT. dicoccoides substitution ndsuext.nodak.edu). lines; QTL, quantitative trait loci; TDIC, Triticum turgidum var. dicoccoides. Published in Crop Sci. 42:637–642 (2002).