Mapping antixenosis genes on chromosome 6A of wheat to greenbug and to a new biotype of Russian wheat aphid

Abstract

Greenbug and Russian wheat aphid (RWA) are two devastating pests of wheat. The first has a long history of new biotype emergence and recently. RWA resistance has just started to break down. Thus, it is necessary to find new sources of resistance that will broaden the genetic base against these pests in wheat. Seventy‐five doubled haploid recombinant (DHR) lines for chromosome 6A from the F1 of the cross between “Chinese Spring’ and the “Chinese Spring (Synthetic 6A) (Triticum dicoccoides × Aegilops tauschii)” substitution line were used as a mapping population for testing resistance to greenbug biotype C and to a new strain of RWA that appeared in Argentina in 2003. A quantitative trait locus (QTL) (br antixenosis to greenbug was significantly associated with the marker loci Xgwm1009 and Xgwm1185 located in the centromere region of chromosome 6A. Another QTL which accounted for most of the antixenosis against RWA was associated with the marker loci Xgwm1291 and Xiinni1150. both located on the long arm of chromosome 6A. This is the first report of greenbug and RWA resistance genes located on chromosome 6A. It is also the first report of antixenosis against the new strain of RWA. As most of the RWA resistance genes present in released cultivars have been located in [he D‐genome, it is highly desirable to find new sources in other genomes to combine the existing resistance genes with new sources.

DIMBOA levels in hexaploid Brazilian wheat are not associated with antibiosis against the cereal aphids Rhopalosiphum padi and Sitobion avenae

“…Moreover, adapta-tion to higher levels of hydroxamic acids could evolve in aphids since they can produce several generations in a short period of time. For instance, a new biotype of the Russian wheat aphid, Diuraphis noxia, was able to break down the resistance of wheat varieties released previously (Castro et al 2005) and, for other plant species too, some resistancebreaking aphid biotypes have been discovered (Dogimont et al 2010). Plants showing different concentrations of hydroxamic acids were able to generate genotypic differences in S. avenae after just a few generations (Figueroa et al 2002) and the assessment of the genetic variability and population structure of S. avenae, collected in Chile, has revealed that some aphid genotypes show highest performance on plants with the highest concentration of hydroxamic acids.…”

Mapping quantitative trait loci for growth responses to exogenously applied stress induced hormones in wheat

“…Two QTLs explaining antixenotic resistance against greenbug and RWA were mapped in the same DHR population (Castro et al 2005) close to the regions identiWed with the present hormone treatments. In addition, a QTL providing resistance against Mycosphaerella graminicola (Stb15) has been mapped in the same region of 6AS of the cultivar 'Arina' (Arraiano et al 2007).…”

“…The construction of the map was described in Castro et al (2005). QTL mapping of the traits was performed using QGENE software (Nelson 1997).…”

“…In wheat, several chromosomes involved in antixenosis, antibiosis and tolerance to greenbug and Russian wheat aphid (RWA) were identiWed in a set of intervarietal chromosome substitution lines (Castro et al 2001) developed between the variety Chinese Spring as the recipient parent and 'Sears Synthetic'. The substitution for chromosome 6A, in particular, showed an increased insect resistance (Castro et al 2005), but signiWcantly lower root dry weight and aerial dry weight, compared to the susceptible parent, both with and without greenbug infestation (Castro et al 2007). This chromosome may thus carry genes for constitutive defenses that aVect photosynthesis, yielding unattractive plants for aphid feeding, or induced repellency.…”

Cereal host interactions with Russian wheat aphid: A review

“…It is speculated that the Dn genes conferring RWA resistance located on wheat chromosome 7DS form a linkage group consisting of Dn1 , Dn2 , Dn5 and Dnx , while Dn9 is located in a defense-gene-rich region of wheat chromosome 1DL (Lui et al 2001(Lui et al , 2002(Lui et al , 2005. However, a quantitative trait locus (QTL), which accounted for most of the antixenosis against RWA that appeared in Argentina in 2003, was mapped to chromosome 6A (Castro et al 2005).…”