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The investigation endeavored to study the distribution and allelic expressivity of hybrid necrosis genes (Ne1and Ne2) in 332 maternal lines comprising 274 triticale × wheat derived homozygous recombinants, 41 winter × spring and spring × spring wheat derived doubled haploid lines, 12 reconstituted wheat lines and 5 released bread wheat cultivars of north-west Himalayan regions utilizing Himalayan genetic resources. Hybridization was executed at Palampur and Lahaul and Spiti, India by crossing maternal parents with two known tester parents C306 (Ne1sNe1sne2ne2) and HD2380 (ne1ne1Ne2mNe2m) to generate F1hybrids. The necrotic lines were categorized into Ne1and Ne2-carriers based on the presence of necrosis genes in F1hybrids. Subsequent screening revealed the presence of 83 Ne2-carriers (25%) and 249 non-carrier genotypes (75%) in the present study. Eighty-three Ne2-carriers comprised 51 triticale × wheat derived homozygous recombinants (11 Ne2s, 6 Ne2ms, 26 Ne2m, 4 Ne2wmand 4 Ne2walleles), 22 winter × spring and spring × spring wheat derived doubled haploid lines (7 Ne2s, 12 Ne2mand 3 Ne2walleles), 9 reconstituted wheat lines (5 Ne2s, 2 Ne2mand 2 Ne2wmalleles) and 1 released variety (Ne2mallele) for necrosis and none of the lines possessed Ne1gene. Analysis of Ne2gene and their linkage properties with other paramount genes make Ne2-carriers superior source for emphasizing the genetic amelioration of wheat through selective hybridization.

A total of 139 triticale × wheat progenies (including recombinant inbred lines and doubled haploids) were developed indigenously. Screening at cytogenetic level using genomic in situ hybridization and fluorescence in situ hybridization revealed maximum progenies (48%) carrying 1RS.1BL translocation. D-R genome substitution ranging from 1 to 7 chromosomes of rye showed significantly more biological yield (9.29 g), 1000 grain weight (48.26 g), number of tillers per plant (6.67) and plant height (106.06 cm) than other progenies depicting the contribution of rye chromatin towards plant yield. Thirteen per cent of lines were found without rye chromatin. Screening of all progenies against yellow rust pathogen revealed about 85% lines to be resistant with varying levels of resistance. In vitro testing for drought tolerance showed non-significant difference among progenies carrying variable rye introgressions. The progenies developed in the present study may present novel germplasm and utilized in the future wheat improvement programmes.

Doubled haploidy breeding from F1population accelerates the varietal development programmes by producing instant homozygosity but the plants undergo only one round of recombination. Generation of doubled haploids (DHs) from F2/F3or backcrossed populations may allow for more recombination and selection of rare homozygous recombinants. However, very few reports on this account are available to suggest utilization of the filial generations that should be utilized for double haploid production. Keeping this in view, the present investigation was formulated to evaluate triticale × wheat derived F1, F2, F3, BC1F1and BC1F2generations towards haploid induction parameters following the Imperata cylindrica-mediated chromosome elimination approach. Based on statistical analysis, the backcrosses (BC1F1and BC1F2) were observed to be significantly better than the F1, F2and F3populations towards haploid induction parameters under consideration. Among the backcrosses, BC1F2outperformed BC1F1towards pseudoseed formation (average 41.28 and 42.50% in 2013–14 and 2014–15, respectively) whereas the latter was significantly better than the former towards haploid embryo formation (average 33.22 and 37.03% in 2013–14 and 2014–15, respectively). Both populations were observed to be at par with each other for haploid regeneration (average 49.36 and 49.56% in 2013–14 and 49.08 and 49.90% in 2014–15) but significantly better than other generations used in the experiment. Hence, involving backcrosses in doubled haploidy breeding programmes may increase the number of haploids and DHs thus resulting in rapid development of mapping populations.

In vitro haploid production followed by chromosome doubling greatly enhances the production of complete homozygous wheat lines in a single generation. This work aimed to develop wheat doubled haploid genetic stock resistant to yellow and brown rust via intergeneric hybridization with Imperata cylindricaand its further characterization. The wheat doubled haploid (DH) line was developed by crossing wheat F1(HS 542/China 84-40,022) with I. cylindrica. This DH-1 was tested against eight races of yellow (110S119, 110S247, 238S119, 78S84, 110S84, 111S68, Tand P) and eighteen races of brown rust (11,12-5, 12-7, 12A, 77, 77-1, 77-2, 77-5, 77-7, 77-8, 77-10, 77A-1, 104-2, 107-1, 108-1, 162-1, 77-9and 104-1) at seedling stage and with mix race of yellow and brown rust in adult plant stage (at Dhaulakuan, Bajaura and Shimla). At the seedling stage, DH-1 showed resistance to all the yellow and brown rust pathotypes except for 77-5race of brown rust. The adult plant response of this DH line also showed resistance to both yellow and brown rust. Based on host pathogen interaction, the DH-1 was postulated to carry leaf rust resistant genes Lr26+ Lr23+ 1 + and yellow rust resistant gene Yr9+ gene. Molecular characterization of the DH line with gene-specific primers showed that the developed DH-1 contains leaf rust resistance genes Lr34, Lr26and Lr32. The DH-1 has semi-spreading growth habit, erect flag leaf attitude, plant height of 94 cm, have scurs and 1000 grain weight of 36 g. The results highlight I. cylindrica-mediated chromosome elimination technique of doubled haploid production as an effective tool for the development of wheat rust resistant lines in the shortest timeframe. This is the first report of genetic stock development for rust resistance in wheat viaI. cylindrica-mediated DH technique.