The Hessian fly resistance gene H21 is present on the wheat-rye wholearm translocation T2BS·2RL and was recently transferred to durum wheat. However, homozygous lines for this translocation have poor plant vigor, low seed set, and are almost completely sterile, making it impossible to use this germplasm directly in durum wheat improvement. The objective of this study was to reduce the rye segment in T2BS·2RL using ph-mediated recombination, thereby making this gene available for durum breeding. A total of 39 primary recombinants from a population of 512 plants (7.6%) were recovered involving 10% of the distal segment of the long arm of rye or wheat. Among these primary recombinants 21 (53.8%) had distal rye chromatin, 12 (30.8%) had distal wheat chromatin, the remaining four had either very distal wheat or rye and two were interstitial recombinants. Ten out of 39 primary recombinants were tested for their resistance to Hessian fly. Three recombinants (Rec. # 1, 2, 3) with about the distal 10% of 2BL arm derived from rye reacted resistant and, thus, had the H21 gene. Two recombinants (Rec. # 4, 5) with very distal rye chromatin reacted susceptible to the Hessian fly. Three other primary recombinants (Rec. # 6,7,8) with the distal 10% of the 2RL arm derived from wheat were susceptible to Hessian fly and did not retain the H21 gene. The remaining two recombinants (Rec. # 9, 10) with very distal wheat segments were resistant and still had the resistance gene H21. The distal primary recombinants with the gene were vigorous and had normal seed set and can now be used in the improvement of durum wheat. Introduction:-The Hessian fly, Mayetiola destructor (Say), is a major insect pest of wheat. Genetic resistance is the most effective and economical means of controlling this insect (Ratcliffe and Hatchett 1997). To date, 29 Hessian fly-resistance genes (H1 through H29) have been identified in Triticum/Aegilops species and in Secale cereale L. (McIntosh et al., 1998). The mechanism of resistance conditioned by these genes is antibiosis, whereby first instars die soon after they begin to feed on plants. A gene-for-gene relationship exists between the resistance in wheat and avirulence in the Hessian fly. Virulence in the insect is conditioned by homozygous recessive pairs of genes (Hatchett and Gallun 1970). As a consequence of this highly specific interaction, 16 biotypes (designated Great Plains and A through O) have been isolated from field populations and are distinguished only by their ability or inability to survive on and stunt wheat with specific resistance genes.Triticum Turgidum L. is an important crop in the Mediterranean region and is grown on approximately 17 millions hectares. Lacking adequate levels of resistance, this crop usually is damaged severely by Hessian fly in the dry areas of northern Africa. In Morocco, yield losses due to damage by this insect have been estimated at up to 36% of the yearly small grain production . Among the identified genes for resistance to Hessian fly, ten have been found to b...

Aegilops tauschii Coss. (2n=14, DD) is a rich source of disease resistance genes for the improvement of cultivated wheat including several resistance genes against Hessian fly. To date, five Hessian fly resistance genes (H13, H22, H23, H24, and H26) have been transferred from Ae. tauschii to common wheat (Triticum aestivum L.). In this study, we attempted the transfer of four genes H22 (1D), H23 (6DS), H24 (3DL), and H26 (4D) from T. aestivum D genome onto A genome chromosomes of T. turgidum. The T. aestivum resistant parents WGRC01 (H22 on 1D), WGRC03 (H23 on 6DS), WGRC06 (H24 on 3DL), and WGRC26 (H26 on 4D) were crossed with T. turgidum cv. Langdon disomic substitution lines LDN 1D(1A), LDN 6D(6A), LDN 3D(3A), and LDN 4D(4A). We targeted the transfer of Hessian fly resistance genes into D-genome substitution chromosomes of T. turgidum by homologous recombination. In total 88 crosses were made. The resulting F 1 plants (345 seeds) were backcrossed with the LDN 5D(5B) substitution line in which chromosome 5B is absent and replaced by a pair of 5D chromosomes with the objective of transferring D genome Hessian fly resistance genes onto A or B genomes of T. turgidum by homoeologous recombination. A total of 2,053 segregating BC 1 F 1 plants were tested for Hessian fly resistance, and the resistant plants (1,132) were backcrossed again with LND 5D(5B) to produce BC 2 F 1 and selfed to produce BC 1 F 2 . In the BC 1 F 1 populations, 24 families segregated for an excess of resistant plants than the expected 1:1 resistant to susceptible plants suggesting that they were putative A-D genome positive recombinants. Mapping analysis using microsatellites was used in these families to identify recombinants between A-and D-genome chromosomes. The data indicated that H22 recombinants were recovered consisting of the distal part of the short arm of 1A, the proximal of 1DS, and the complete long arm of 1D. The recombinant can be described as T1AS-1DS1DL.Corresponding Author:-Moha Ferrahi. Address:-Moha Ferrahi, National Institute for Agricultural Research (INRA), Regional Center of Meknes, BP 578, Meknes, Morocco 50000. ISSN: 2320-5407Int. J. Adv. Res. 5(11), 728-750 729The recombinant involving H23 probably consisted of the whole short arm of 6D and the long arm of 6A, and is described as T6DS6AL. The centromeric marker indicated that this recombinant has the centromere from chromosome 6A. In addition, monosomic substitution lines were recovered for the remaining resistance genes H24 and H26. These monosomic substitution lines are useful germplasm for further manipulation aimed at transferring genes H24 and H26 to durum wheat.Copy Right, IJAR, 2017,. All rights reserved. …………………………………………………………………………………………………….... Introduction:-Each year infestations of the Hessian fly, Mayetiola destructor (Say), cause serious damage to both bread and durum wheat in many parts of the world. In the United States, the use of genetic resistance has protected common wheat for the last 50 years (Ratcliffe and Hatchett, 1997). Genetic resistanc...