Genetic mapping of a major gene in triticale conferring resistance to bacterial leaf streak

Abstract

A major gene conferring resistance to bacterial leaf streak was mapped to chromosome 5R in triticale. Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa (Xtu), is an important disease of wheat and triticale around the world. Although resistance to BLS is limited in wheat, several triticale accessions have high levels of resistance. To characterize the genetic basis of this resistance, we developed triticale mapping populations using a resistant accession (Siskiyou) and two susceptible accessions (UC38 and Villax St. Jose). Bulked segregant analysis in an F population derived from the cross of Siskiyou × UC38 led to the identification of a simple sequence repeat (SSR) marker (XSCM138) on chromosome 5R that co-segregated with the resistance gene. The cross of Siskiyou × Villax St. Jose was advanced into an F recombinant inbred line population and evaluated for BLS reaction. Genetic linkage maps on this population were assembled with markers generated using genotyping-by-sequencing as well as several SSR markers previously identified on 5R. Quantitative trait locus (QTL) mapping revealed a single major QTL on chromosome 5R, underlined by the same SSR marker as in the Siskiyou × UC38 population. The F hybrids of the two crosses were highly resistant to BLS, indicating that resistance is largely dominant. This work will facilitate introgression of this rye-derived BLS resistance gene into the wheat genome by molecular marker-mediated chromosome engineering.

The translucens group of Xanthomonas translucens: Complicated and important pathogens causing bacterial leaf streak on cereals

“…translucens pv. undulosa strains, suggesting the presence of a gene‐for‐gene interaction in triticale (Johnson et al , ; Wen et al , ). However, it remains unknown if the wheat– X .…”

“…Using partial and high levels of BLS resistance in small grain crops, the heritability and genetics of BLS resistance were investigated (Duveiller et al , ; El Attari et al , ; Tillman and Harrison, ; Adhikari et al , ; Kandel et al , ; Wen et al , ). The heritability of BLS resistance in wheat was reported to vary from low to high depending on the resistant lines used (El Attari et al , ; Tillman and Harrison, ).…”

“…Using three F 2 populations derived from Terral 101 (resistant), Coker 9877 (moderately resistant), Pioneer 2548 (susceptible), and Coker 9766 (susceptible), Tillman and Harrison () also detected the presence of multiple genes controlling BLS resistance in these wheat cultivars. However, resistance to BLS in a few triticale lines appears to be qualitative and dominant (Johnson et al , ; Wen et al , ).…”

“…A total of four QTLs distributed on 2B, 6D, 7A, and 7B were identified by Ayana () using a recombinant inbred lines (RILs) population from the cross of a partially resistant (SD52) and susceptible wheat lines (SD1001) and a genetic map consisting of 1,211 SNP markers. Wen et al () developed two triticale populations derived from a highly resistant genotype (Siskiyou) and two highly susceptible genotypes (UC38 and Villax St. Jose), and mapped a major resistance gene, Xct1 , on chromosome 5R.…”

“…Previous studies coupled with our recent studies showed that several triticale lines harbour dominant resistance genes to some X. translucens pv. undulosa strains, suggesting the presence of a gene-for-gene interaction in triticale (Johnson et al, 1987;Wen et al, 2018). However, it remains unknown if the wheat-X.…”