Resistance to fusarium head blight in wheat: QTL mapping, role of lignin
Abstract
Fusarium head blight (FHB) of wheat (Triticum aestivum L.), mainly caused by Fusarium graminearum in North America, can result in severe economic losses due to reduced yield and contamination of grain by mycotoxins. Development of adapted resistant cultivars has become a major objective of many wheat-breeding programs. Two connected populations of recombinant inbred lines (RILs) were developed by single-seed descent from crosses of the moderately susceptible, adapted cultivar Patterson with the two exotic lines Huapei 57-2 and Bizel, respectively resistant and moderately resistant to FHB. RILs were evaluated for type II resistance, following point inoculation, in one field experiment and two greenhouse tests. In the population Huapei 57-2/Patterson, a major quantitative trait loci (QTL) was identified on chromosome 3BS. It is likely the same as the one tagged using lines derived from Sumai 3. Additional QTL were detected on chromosomes 3A, 3BL, and 5B. Simple Sequence Repeat (SSR) markers identified in this research will facilitate the marker-assisted development of FHB resistant, adapted lines. Disease responses of RILs from the population Bizel/Patterson were inconsistent across tests. Interestingly, a QTL on 3BS was detected. No Asian germplasm appears in the pedigree of Bizel: Blé Bohémien / rye // Oro /3/ variant of Hauters. In addition, it was shown using rye-specific repetitive DNA sequences that Bizel does not contain rye (Secale cereale) chromatin. Based on the analysis of the SSRs, Xbarc133 and Xbarc147, tightly associated with the 3BS QTL, it is suggested that Bizel might have a different resistance allele than Sumai 3. The role of lignin on FHB resistance was investigated. Ning 7840 and Len, respectively resistant and susceptible to FHB, were Fusarium and mock-inoculated. Lemmas at several time points were analyzed by pyrolysis—gas chromatography—mass spectrometry. At flowering, Ning 7840 has a high level of ferulic acid and probably a lignin rich in syringyl-residues compared to Len. It is proposed that active and localized accumulation of syringyl-type lignin in response to Fusarium infection, in addition to innate cell wall characteristics might explain the high level of type II resistance of Ning 7840.
Degree
Ph.D.
Advisors
Ohm, Purdue University.
Subject Area
Agronomy|Plant pathology|Plant propagation
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