Contents - Faperta

174 Biotechnological Approaches for Pest Management and Ecological Sustainability
RFLP markers linked to two Hessian fl y resistance genes in wheat from Triticum tauschii
(Coss.) Schmal. have also been identifi ed (Ma et al., 1993). A new Hessian fl y resistance
gene (H30) transferred from the wild grass, Aegilops triuncialis L. to hexaploid wheat, has
also been identifi ed (Martin-Sanchez et al., 2003). Five SSR markers (Xgwm136, Xcfa2153,
Xpsp2999, Xgwm33, and Xbarc263) are linked to the Hessian fl y resistance gene, Hdic on the
short arm of the wheat chromosome 1A, which is in the same region as H9, H10, and H11
(X.M. Liu et al., 2005). The fl anking markers Xgwm333 and Xcfa2153 have been mapped at
0.6 cM and 1.4 cM, respectively. Hdic confers a high level of antibiosis to Hessian fl y biotypes
GP and L, and the strains vH9 and vH10. Allelic tests indicated that resistance genes
in SW 8 and SW 34 may be allelic to H26 and H13, or correspond to paralogs at both loci,
respectively (X.M. Liu, Smith, and Gill, 2005; Wang et al., 2006). The genes H26 and H13
have been assigned to chromosomes 3D and 6D, respectively. H13 maps to the distal cluster
of genes on chromosome 6DS (X.M. Liu, Gill, and Chen, 2005). Hessian fl y resistance
from TA 2473 (wild diploid goat grass, T. tauschii) is governed by one dominant gene located
on chromosome 4D (Cox and Hatchett, 1994). This gene, designated as H26, is the only
Hessian fl y resistance gene known to be located on 4D. Gene H26 conditions a high level
of antibiosis to Biotype L and has been transferred into a germplasm line, KS92WGRC26,
which has most of the desirable agronomic traits of its recurrent parent, Karl. A new
Hessian fl y resistance gene from Aegilops ventricosa Tausch. present in 4D(4M v ) substitution
line H-93-33 derived from the cross (Triticum turgidum Desf. H-1-1 A. ventricosa
no. 11) Triticum aestivum, H-10-15), confers resistance to the Spanish population of
M. destructor, and is inherited as a single dominant trait (Delibes et al., 1997). The resistance
gene H27 is allelic to that of A. ventricosa no. 10, but nonallelic to H3 and H6. A new source
of resistance to the highly virulent and widespread biotype L of Hessian fl y has been identifi
ed in an accession of tetraploid durum wheat, T. turgidum (Williams et al., 2003). Genetic
analysis and deletion mapping revealed that this line was homozygous for a single locus
for resistance, H31, residing at the terminus of chromosome 5BS. H31 is the fi rst Hessian fl y
resistance gene to be placed on 5BS. AFLP analysis identifi ed a marker, linked to the resistance
allele, which retained its polymorphism after being converted to a highly specifi c
sequence-tagged site marker, Xupw4148. This dominant 128-bp marker maps 3.3 cM from
the H31 resistance locus and amplifi es in resistant plants only.
Ma et al. (1998) mapped resistance genes Dn2 and Dn4 conferring resistance to the Russian
wheat aphid, D. noxia. The genes Dnl, Dn2, Dn5, Dn6, and Dnx are located on the short arm
of wheat chromosome 7D (X.M. Liu et al., 2001; X.M. Liu, Smith, and Gill, 2002). They are
allelic or a cluster of completely linked resistance genes, as there is no segregation for susceptibility
to Russian wheat aphid among progeny from crosses involving plants containing
each of the six genes in all possible combinations (X.M. Liu, Smith, and Gill, 2005).
QTLs for resistance to greenbug, S. graminum in wheat have also been identifi ed (Castro
et al., 2004). Weng and Lazar (2002) used AFLP and SSR markers to tag greenbug resistance
gene, Gb3 in wheat. The Gb gene conferring resistance to S. graminum, is inherited as a
single dominant trait (Zhu et al., 2005). Microsatellite markers Xwmc157 and Xgdm150 fl ank
Gbx1 at 2.7 and 3.3 cM, respectively (Weng, Devkota, and Rudd, 2005). Xwmc671 is linked
to Gba, Gbb, Gbc, and Gbd at 34.3, 5.4, 13.7, and 7.9 cM, respectively; while Xgdm150 is distal
to Gbc at 17.7 cM. Gbd appears to be a new resistance gene, and is different from Gbx1 or
Gbz. The genes Gbx1, Gba, Gbc, and Gbd are either allelic or linked to Gb3. Gby is another
greenbug resistance gene in the wheat line ‘Sando’s selection 4040, and is inherited as a
single semidominant gene located on wheat chromosome 7A (Boyko, Starkey, and Smith,
2004). Gby was mapped to the area in the middle of the “island” of putative defense
response genes that are represented by RFLP markers (Xpsr119, XZnfp, Xbcd98, and Pr1b),