High-density mapping of the major FHB resistance gene Fhb7 derived from Thinopyrum ponticum and its pyramiding with Fhb1 by marker-assisted selection

Abstract

Wheat lines with shortened Th. ponticum chromatin carrying Fhb7 and molecular markers linked to Fhb7 will accelerate the transfer of Fhb7 to breeding lines and provide an important resource for future map-based cloning of this gene. Fusarium head blight is a major wheat disease globally. A major FHB resistance gene, designated as Fhb7, derived from Thinopyrum ponticum, was earlier transferred to common wheat, but was not used in wheat breeding due to linkage drag. The aims of this study were to (1) saturate this FHB resistance gene region; (2) develop and characterize secondary translocation lines with shortened Thinopyrum segments carrying Fhb7 using ph1b; (3) pyramid Fhb7 and Fhb1 by marker-assisted selection. Fhb7 was mapped in a 1.7 cM interval that was flanked by molecular markers XsdauK66 and Xcfa2240 with SSR, diversity arrays technology, EST-derived and conserved markers. KS24-2 carrying Fhb7 was analyzed with molecular markers and genomic in situ hybridization, confirming it was a 7DS.7el2L Robertsonian translocation. To reduce the Thinopyrum chromatin segments carrying Fhb7, a BC1F2 population (Chinese Spring ph1bph1b*2/KS24-2) was developed and genotyped with the markers linked to Fhb7. Two new translocation lines (SDAU1881 and SDAU1886) carrying Fhb7 on shortened alien segments (approximately 16.1 and 17.3% of the translocation chromosome, respectively) were developed. Furthermore, four wheat lines (SDAU1902, SDAU1903, SDAU1904, and SDAU1906) with the pyramided markers flanking Fhb1 and Fhb7 were developed and the FHB responses indicated lines with mean NDS ranging from 1.3 to 1.6 had successfully combined Fhb7 and Fhb1. Three new molecular markers associated with Fhb7 were identified and validated in 35 common wheat varieties. The translocation lines with shortened alien segments carrying Fhb7 (and Fhb1) and the markers closely linked to Fhb7 will be useful for improving wheat scab resistance.

Disease Impact on Wheat Yield Potential and Prospects of Genetic Control

“…Heading, plant height, and anther extrusion also show significant correlations with FHB resistance (12). Although resistance QTLs were identified on all 21 chromosomes (53), only seven are designated as FHB resistance genes, of which only Fhb1, Fhb2, Fhb4, and Fhb5 are from wheat and Fhb3, Fhb6, and Fhb7 from wild relatives (36). Progress in breeding has been relatively slow and the development of high-yielding cultivars with resistance similar to the old Chinese cultivar Sumai 3 remains a breeding challenge.…”

Breeding strategies and advances in line selection for Fusarium head blight resistance in wheat

“…Further resistance sources include the QTL Fhb4 and Fhb5 found in 'Wangshiubai' (Xue et al 2010(Xue et al , 2011 and Qfhs.nau-2DL identified in the breeding line CJ9306 (Jiang et al 2007a, b). In addition, Fhb7 was recently detected in the wild species Thinopyrum ponticum (Guo et al 2015).…”

“…Recently, UMN10 was complemented by a userfriendly KASP marker derived from the sequenced UMN10 PCR product (Schweiger et al 2016). For other resistance QTL markers flanking the QTL region are employed and for Fhb7, a major QTL derived from Thinopyrum ponticum, translocation lines with shortened alien segments and closely linked markers were developed (Guo et al 2015).…”

Harnessing Genetic Diversity of Wild Gene Pools to Enhance Wheat Crop Production and Sustainability: Challenges and Opportunities

“…Similarly, and in this case exploiting the high degree of homology relating two group 7 chromosomes (named 7el 1 and 7el 2 ) of different Th. ponticum accessions, the Lr19 gene (located on the 7el 1 L arm) was pyramided, both in bread wheat [39][40][41] and in durum wheat [41], with Fhb-7el2, a major QTL for resistance to Fusarium head blight (FHB) mapped on 7el 2 L (recently renamed Fhb7 [42]). …”