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

Abstract

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a serious disease problem on durum wheat (Triticum turgidum L. var. durum) in the USA. To date, the resistance to FHB available in hexaploid wheat (T. aestivum L.) sources has not been transferred successfully to tetraploid durum. In the 1980s, USDA geneticist L.R. Joppa produced a set of disomic lines [LDN(DIC)] derived from wild emmer (T. turgidum L. var. dicoccoides). Each line had a different pair of chromosomes from T. dicoccoides substituted for the corresponding ‘Langdon’ durum chromosomes. The purpose of this study was to determine if any of the LDN(DIC) lines showed useful levels of resistance to FHB. We tested these lines for FHB response by inoculation with F. graminearum in the greenhouse. Inoculation was accomplished via the single spikelet method, in which a droplet of conidiospore suspension is placed into one spikelet per spike followed by mist–high humidity for 3 d to establish infection. After 21 d, spikes were scored for extent of FHB symptoms and the average disease severity of the lines compared. A low disease severity score in this test indicated the presence of resistance to FHB in that line. Each test was replicated and the tests were done five times. In each test, some lines differed significantly. One line, LDN(DIC‐3A), was consistently less susceptible and another line, LDN(DIC‐2A), was consistently more susceptible than the parent Langdon durum, which itself showed an intermediate FHB reaction. Several other LDN(DIC) lines showed a trend either for increased or reduced susceptibility to FHB. Since each line differs by a single chromosome pair, the results suggest that genes affecting FHB resistance are present on several different T. dicoccoides or Langdon durum chromosomes.

Reaction of Wild Emmer Wheat Accessions to Fusarium Head Blight

“…Although Israel A per se is susceptible to FHB (Table 1; Stack et al, 2002a), the FHB resistance QTL on chromosome 3A is probably suppressed by one or more other genes present in the genomes of Israel A. Other research suggests that the suppressor gene is located on chromosome 2A (Stack et al, 2002a;Garvin et al, 2003).…”

“…Wheat lines with high levels of FHB resistance generally possess multiple resistance genes, which act in an additive manner to confer resistance. Studies have shown that such genes, when present individually, confer only intermediate resistance (Waldron et al, 1999;Stack et al, 2002aStack et al, , 2002b. Accessions exhibiting an intermediate reaction could have a minor gene(s) for resistance, thus preventing extreme susceptibility.…”

“…Accessions exhibiting an intermediate reaction could have a minor gene(s) for resistance, thus preventing extreme susceptibility. An intermediate FHB reaction could also be caused by suppressor genes, which prevent expression of some FHB resistance genes (Stack et al, 2002a).…”

“…Two TDIC accessions, Israel A and PI 481521, were identifi ed to contain FHB resistance genes in previous studies (Stack et al, 2002a. A major FHB resistance QTL was detected on chromosome 3A in Israel A (Otto et al, 2002) and has been utilized in durum breeding (E.M. Elias, personal communication, 2006).…”

“…Strains R1267 and R1270 had been isolated from blighted wheat heads in eastern North Dakota and had been chosen for the ability to cause FHB (Stack and McMullen, 1985). All three cultures have consistently produced FHB symptoms in wheat (Stack et al, 1997(Stack et al, , 2002a.…”