Leaf rust, caused by Puccinia triticina Eriks., is one of the destructive foliar diseases of wheat inflicting significant yield losses in susceptible cultivars. Additionally, the development of new pathotypes virulent to major genes are frequent and thus, necessitates the diversification of resistance bases in cultivated varieties. Hence, the present study was undertaken to transfer the novel leaf rust resistance gene LrSel.212, identified in a rye introgression line in bread wheat, Selection 212, into the elite but susceptible bread wheat cultivar HD2932 as the recipient/recurrent parent. An integrated approach combining conventional backcross breeding with molecular markers were employed in the current breeding program. The hybridity of F1 plants were confirmed through SSR marker showing length polymorphism between parents. The F1 plants between HD2932 as recurrent parent (RP) and Selection 212 as donor parent (DP) was backcrossed with RP to generate BC1F1 generation. The monomorphic SSR marker linked with target gene restricted the foreground selection in identifying heterozygous plants carrying recessive allele. Hence, the conventional approach was followed to transfer a recessive gene. The BC1F1 plants were selfed to generate the BC1F2 generation and resistant plants were identified through phenotyping for leaf rust. Further, phenotypically selected resistant plants from BC1F2 generation were crossed to RP to develop BC2F1 generation. The BC2F1 plants were again selfed to get the BC2F2 generation. The resistant plants were identified from BC2F2 generation again based on phenotyping for rust resistance. The resistant plants from backcross generation were further selected based on phenotypic similarity with RP. A total of 10 BC2F2 resistant plants were selected with the most phenotypic similarity to the RP HD2932. Background analysis with 110 genome-wide polymorphic SSR markers in these plants reveal 88.18% to 93.64% recurrent parent genome recovery. Seedling resistance test of BC2F3 lines with diverse leaf rust pathotypes showed a stable resistant reaction in all the NILs. Agronomic performance of 10 NILs were evaluated and found to be at par for most of the NILs compared with the recurrent parent. Among the lines, NIL-4 and NIL-6 were found to be significantly higher-yielding than RP. The newly developed NILs with leaf rust resistance introgressed from rye holds immense potential in managing the leaf rust incidence and will further help in broadening the diversity of resistance base.

Wheat variety HD3437 is an improved version of the mega-wheat variety HD2967, with resistance to leaf and stripe rusts. It carries a seedling stripe rust resistance gene, Yr10, and a pleiotropic adult plant resistance gene, Lr34/Yr18 conditioning adult plant resistance to both leaf and stripe rusts. Marker-assisted backcrossing was used to develop Near-isogenic lines (NILs) of HD2967 with Lr34/Yr18 (91.21

Bread wheat is the second most important cereal globally, fulfilling 20

Wheat plays a pivotal role in global food and nutritional security. To meet the growing demand for food, increasing wheat production through hybrid development remains an untapped avenue. However, the autogamy of wheat causes a significant challenge for hybrid development. The present study aimed to convert the elite bread wheat cultivars HD3086 and HD2932 into a cytoplasmic male-sterile (CMS) lines using the CMS donor parent (A-GW365) through a backcross breeding approach. Background analysis using 152 and 145 SSR markers confirmed ˃95

The spike length (SL) in wheat (Triticum aestivum L.) is one of the most essential component traits for grain yield. Thus, identifying genomic regions associated with SL could advance molecular breeding for grain yield through dissecting the genetic basis of spike development in wheat. The current investigation developed a linkage map for SL using a set of 92 F2:16 RILs, which were genotyped using the 35K SNP array. QTL mapping for SL revealed 11 QTLs on chromosomes 1D, 3B, 3D, 4A, 5A, 6B, 6D, and 7B. A stable major QTL, Qsl.nhv-4A.a (LOD: 5.77–7.61; R2: 23.20–28.66

Hybrid necrosis in wheat occurs because of two dominant complementary genes, Ne1 and Ne2, located on chromosomes 5BL and 2BS, respectively. While transferring rust resistance genes in some Indian wheat varieties, hybrid necrosis was observed with HD2967 and HD2733, while no necrosis was observed with HD2932 and HD3059. A marker-assisted backcrossing program was initiated to eliminate the necrosis gene present in HD2967 and HD2733. Markers linked to Ne1 (Xbarc74) and Ne2(Leq54_LrLC10and Leq22_LrLC10) genes were used in marker validation using a set ofgenotypes.The linked markers showed the presence of the Ne1 gene in wheat varieties HD2967, HD2733 and positive check of Ne1, C306 and Ne2 gene in Parula as that of positive check Sonalika. The wheat varieties HD2932 and HD3059 showed the absence of Ne1 and Ne2 genes as negative checks, Agra Local and NI5439. For marker-assisted elimination of Ne1 from HD2967 and HD2733 or substitution of dominant Ne1 allele with recessive ne1 allele, HD2932 was used as a donor parent. Near isogenic Lines (NILs) of HD2967 (RPG = 96.80%) and HD2733 (RPG = 95.55%) were identified in BC2F3 generations. Plants homozygous for recessive allele (ne1ne1) and dominant allele (Ne1Ne1) were crossed with Ne2carrier Sonalika (Ne2Ne2) to test the effectiveness of marker-assisted selection. While all the F1s of Ne1Ne1 died at the seedling stage, the F1s of ne1ne1 were viable and produced normal seeds. The present study validated the available molecular markers of Ne1 and Ne2 and used these markers to develop NILs devoid of necrosis gene Ne1. The superior genotypes (NILs) without any necrosis gene can be used freely in developing superior male sterile (A) lines for hybrid breeding programmes or in the transfer of genes of economic importance without fear of getting hybrid necrosis.

Developing improved crop cultivars is essential for confronting adverse environmental conditions. Rapid cultivar development requires reducing crop duration through rapid generation advancement (RGA) strategies. Extreme conditions that allow five to six crops annually may not provide plant breeders the opportunity for selection based on phenological traits and also necessitate a well-equipped growth chamber. The present study aimed to develop an RGA protocol under natural daylight during the summer season in sub-tropical conditions, incorporating irrigation, and plant density modulation alongside the chilling treatment of harvested seed. Wheat cultivars HD2932 and HD3086 were grown in 4-inch plastic pots with either one or four seeds per pot.The plants grown at higher density flowered 3 to 4 days earlier than their low-density counterparts. Irrigation was stopped either at 15 or 25 days after anthesis for forced maturity in different sets of plants, and the matured seeds were harvested after 20 days of the last irrigation. Consequently, the seed-to-seed cycle was shortened to 90 to 95 days compared to the regular cropping season (140-150 days). The seeds were subjected to chilling treatment at 4 degrees C prior to sowing, and it was observed that chilling treatment for up to 72 hours can increase germination percentage beyond 90%. The protocol standardized in the current study can help to get two wheat crops with only temperature-controlled chambers in sub-tropical conditions during the summer season. The method can be used intermittently by growing two summer crops and a rabi crop, permitting selection under intermittent moderate RGA and natural growing conditions.

In present investigation, local strain of Tagetes patula L. was used for in vitro androgenesis with floret size ranging from 2 to 4.5 mm. The results indicated that treatment (T3) i.e. floret size - 3 to 3.5 mm cultured in EMS (Enriched Murashige and Skoog - MS + organic and inorganic supplements + 5 % coconut water) medium supplemented with 2.0 ml/l BAP + 0.5 ml/l NAA + 3 % sucrose + 0.8 % agar-agar was found best for different parameters. Screening of anther derived regenerants was done through cytological analysis and chloroplast counting of stomatal guard cells. The results revealed that in cytological analysis out of 25 plants screened, one plant (4 %) was dihaploid, 15 plants (60 %) were tetraploids and 9 plants (36 %) were polyploids. Whereas in chloroplast counting, out of 25 plants screened of which one plant (4 %) was di-haploid with mean of 8 chloroplasts in the guard cells, 15 plants (60 %) were tetraploids with mean of 16 chloroplasts in the guard cells and 9 plants (36 %) were polyploids with mean of 18 to 20 chloroplasts in the guard cells. Finally one haploid from anther derived regenerants was isolated and confirmed by cytological analysis and chloroplast counting.

Rust diseases, caused by fungal pathogens, are a significant threat to global wheat production, including in India. The 2NvS translocation from Aegilops ventricosa, carrying the Lr37 + Sr38 + Yr17 gene cluster, has been crucial in developing rust-resistant wheat varieties. In this study, conventional backcross breeding was initially employed to integrate this gene cluster into ten Indian bread wheat cultivars, leading to the development of BC7F8 near-isogenic lines (NILs) with rust resistance. Comprehensive phenotyping at both juvenile and mature plant stages was done to select for desirable traits. However, this method was time-consuming and dependent on consistent disease pressure. The development of NIL’s took almost a decade and by the time the recurrent parents chosen were no longer in cultivation. To overcome these challenges, marker-assisted backcross breeding was subsequently employed, utilizing the VENTRIUP/LN2 molecular marker to verify the presence of the gene cluster which is more efficient and reliable in selecting desired traits. This approach enabled the efficient introgression of desirable traits into modern wheat varieties such as HD 2733, PBW 343, DBW 39, HD 2967, and HW 2045, specifically targeting the North Eastern Plain Zone of India. By shifting from conventional to marker-assisted backcross breeding using the VENTRIUP/LN2 marker, this study introduced a novel method that accelerated the development of rust-resistant lines, enhancing wheat production in rust-prone regions.

Utilization of crop wild relatives of wheat can be very effective in building the genetic diversity to cater to the evolving strains of disease pathogens. Aegilops speltoides is a rich source of rust resistance genes however transferring those to wheat genome can be tedious due to co-transfer and preferential transmission of undesirable genes causing gametocidal activity. Such an unholy association was observed in Triticum aestivum-Ae. speltoides derivative line Sel. 2427 which possess the broad-spectrum leaf rust seedling resistance gene (LrS2427). Molecular analysis based on 35 K wheat breeder’s array revealed the maximum percentage of Ae. speltoides genome introgression on homoeologous group 2. In situ hybridization studies revealed the presence of S genome in Sel. 2427, showing six translocations on four chromosomes. Karyotyping using repetitive probe (AAG)6 revealed that the two chromosomes involved are 2D and 2B. Genic regions causing gametocidal activity were identified by dissecting it into component traits and QTLs on 2D and 2B chromosomes were revealed in case of the trait seed shrivelling index. To break the inadvertent association of LrS2427 with gametocidal genes, F1(Agra Local X Sel. 2427) seeds were irradiated with gamma rays and stable leaf rust resistant mutants lacking gametocidal activity were developed. These mutants showed resistance to different races of leaf rust pathogen and showed superior agronomic performance as well. These mutants could be a great resource in wheat improvement for utilization of the leaf rust resistance gene LrS2427 without any yield penalty.

Wheat stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is one of the major rust fungi that causes severe reduction in yield across the world. Gene pyramiding offers to stack resistant genes in hybrids by incorporating them into their parents. An attempt has been made to introgress the stripe rust resistance genes Yr10 and Yr15 into maintainer line 365B and restorer line 1752 R to optimize the yield potential of hybrids developing at IARI, New Delhi. B (maintainer) and R (Restorer) lines were crossed with their respective donors for Yr10 (AvocetYr10) and Yr15 (HD2967 + Yr15) genes. F1 and backcross generations were screened with linked and validated SSR markers Xpsp3000 for Yr10 in B line and Xgwm273 for Yr15 in R line. Based on marker association, plants carrying Yr10 in B line and Yr15 in R line in each backcross generation were further selected for background recovery. BC2F1 was selfed to obtain BC2F2. Marker assisted breeding helped to reduce the time and effort to improve the parental lines. These improved B lines and R lines will be used for hybrid development after doing background selections. The resistance in B and R lines will ensure the maximum harnessing of heterosis which could be declined due to disease occurrence.

Key message: A putatively novel leaf rust resistance gene, introgressed from Triticum monococcum into durum, temporarily named as LrTm64-8 and mapped on chromosome 2AS will aid in broadening the genetic base of rust resistance in wheat. A leaf rust resistance gene, tentatively named as LrTm64-8 was introgressed into durum wheat from diploid species Triticum monococcum (2n = 2x = 14, genome AA) by direct hybridization. The Introgression Line DTM648 showed wide spectrum of resistance against a panel of 18 pathotypes of leaf rust pathogen Puccinia triticina Eriks. Genetic analysis of leaf rust resistance in DTM64-8 was performed using F1, F2 and F2:3 generations derived the cross DTM64-8/Malvi Local. The results showed a single dominant gene for leaf rust resistance. The resistance gene LrTm64-8 was mapped on short arm of chromosome 2A using both SNP-based PCR markers and SSR markers. Initially, polymorphic SNPs in Bulked Segregant Analysis (SNP) were identified and primers were designed to convert SNPs into PCR-based markers. Additionally, polymorphic SSR markers were identified in the putative genomic region carrying the leaf rust resistance gene. The final map was constructed using one SNPbased PCR marker and three SSR markers spanning a distance of 33.4 cM. LrTm64-8 was flanked by SNP AX94756068 and Xwmc522 on chromosome 2AS. SSR marker Xwmc522 was closest at 3.7 cM proximal to the resistance gene. The resistance gene LrTm64-8 was distinguished from other leaf rust resistance genes mapped on short arm of chromosome 2A by molecular markers and rust response. While all other leaf rust resistance genes identified on chromosome 2AS are mapped in hexaploid wheat, the resistance gene LrTm64-8 was introgressed and mapped in tetraploid durum wheat and may be useful in broadening the genetic base of rust resistance in both durum and bread wheat.

The leaf rust (Puccinia triticina f. sp. tritici), stripe rust (Puccinia striiformis f. sp. tritici), and stem rust (Puccinia graminis f. sp. tritici) are major fungal constraints affecting wheat production worldwide. Identifying and deploying wheat varieties with diverse resistance are the best ways to manage all the rusts. Therefore, a continuous search goes on to identify diverse germplasm with effective rust resistance that expresses at different stages of plant growth (seedling and adult plant). A set of 22 rust resistant wheat genotypes and 4 checks (controls), viz., Avocet-Yr10, Avocet -Yr15, Agra Local, and respective positive checks were studied for characterising rust resistance genes using host-pathogen interactions complemented by molecular markers. Among 22 elite genotypes, 05 genotypes amplified 191 bp fragment with marker PSY1E1, confirmed the presence of gene Lr19/Sr25. These genotypes also expressed resistance to most virulent leaf rust pathotypes, 77-5 and 77-9 in host-pathogen interaction test (HPI). Seven genotypes showed the presence of Lr34/Yr18/Sr57/Pm38/Ltn1 in homozygous state, whereas G4 showed its presence in heterozygous condition. Among 22 genotypes, 16 genotypes possessed Yr10. Five genotypes (22.7%) exhibited two gene combinations, Lr19/Sr25, and Yr10 as revealed through the detection of 191 bp fragment with marker PSY1E1 and 260 bp fragment with co-dominantly inherited microsatellite marker Xpsp3000, respectively. All five genotypes (G2, G3, G8, G9, and G18) also expressed brown glumes controlled by the gene Rg1 tightly linked to Yr10 on the 1BS chromosome. Broad spectrum rust resistance present in these lines in good agronomic backgrounds could be used as potent genetic donors for diverse and durable rust resistance breeding programmes in wheat.

A high-yielding and well-adapted wheat variety for central and peninsular India HD2932 was improved for three types of wheat rusts by introgressing genes Lr19/Sr25, Lr24/Sr24 and Yr10 and a new variety HD3407 (Unnat HD2932) was developed. The linked genes, Lr19/Sr25 and Lr24/Sr24, were derived from Thinopyrum (syn. Agropyron), whereas Yr10 was derived from Moro wheat (Triticum aestivum L.). NILs (> 90

Hybrid development is one of the most promising strategies for boosting crop yields. Parental lines used to create hybrids must have good per se performance and disease resistance for developing superior hybrids. Indian wheat line HD3209 was developed by introducing the rust resistance genes Lr19/Sr25 into the background of popular wheat variety HD2932. The wheat line HD3209 carrying Lr19/Sr25 has been successfully and rapidly converted to the CMS line A-HD3209, with 96.01% background genome recovery, based on selection for agro-morphological traits, rust resistance, pollen sterility, and foreground and background analyses utilizing SSR markers. The converted CMS line A-HD3209 was completely sterile and nearly identical to the recurrent parent HD3209. Based on high per se performance and rust resistance, the study concludes that the derived CMS line A-HD3209 is promising and can be employed successfully in hybrid development.

Breeders have extensively used marker-assisted selection to improve the agronomically superior varieties for disease resistance. Here, the mega wheat variety of India, HD3086, has been improved for leaf rust resistance by transferring a leaf rust resistance gene LrTrk from Triticum turgidum var. durum cv. Trinakria (AABB, 2n = 4X = 28). Taking a tetraploid donor parent instead of a hexaploid produced partial sterility in initial generations, but fertility improved beyond BC2F1 generations and aided in the rapid and higher recovery of recurrent parent genomes. Leaf rust resistance gene LrTrk was selected in every backcross generation with the help of resistance gene linked markerXgwm234 and further confirmed by rust screening. Further, rigorous phenotypic selection of plants with rust resistance gene LrTrk for their phenotypic similarity to recurrent parent HD3086 in backcross generations helped us identify six homozygous NILs in BC2F3 generation. All six NILs carried more than 95% of the recurrent parent genome (RPG) when analyzed with polymorphic markers between the parents. The six NILs also showed no difference in the ago-morphological traits compared to RP HD3086. Out of six, one NIL, HD3086+LrTrk-2, was selected with numerically higher yielding than recurrent parent HD3086 and at par performance for all other traits. This NIL will be nominated in AICRP trials before being it to the farmer's field. The improved NIL will provide an alternative for the susceptible cultivar from the farmer's field and broaden the genetic base of wheat cultivars grown in India.

For varietal improvement, parental genotypes are crossed and advanced to generate homozygous lines with selection for desirable traits like disease resistance and yield. In the current study, leaf rust resistance gene Lr52 from Lr52/Yr47/2*Mace, the donor parent (DP), transferred to the recurrent parent (RP) HD3086, a popular Indian wheat cultivar, which has become susceptible to leaf rust. During the backcross breeding, the plants were grown sequentially under natural field conditions during the winter season and under controlled environmental conditions to take two crop generations during the summer season. Generations comprising F1, BC1F1, and BC2F13 plants were developed by crossing and successive backcrossing with RP HD3086 and further selfing to generate homozygous resistant lines. Plants with leaf rust resistance in backcross generations were selected phenotypically to identify the superior or similar plants as of RP HD3086. The Lr52/Yr47-linked SSR marker icg16c004_2 was initially utilized to confirm hybridity and foreground analysis in the BC1F1 generation but was found to be recombinant. Homozygous resistant (HR) lines in BC2F3 generation were selected based on leaf rust disease score and phenome recovery. Finally, the SSR markers unveiling parental polymorphism across the genome were employed to estimate the background recovery of phenotypically selected superior plants, revealing a recovery of 91.48-94.81 % of RP genome. The selected improved lines of HD3086+Lr52 displayed similar performance for most agro-morphological traits, and a few lines were also found to yield significantly superior to that of RP HD3086. Overall, the study shows the practical utility of phenotypic selection with intermittent selection under controlled and natural field conditions for improving popular cultivars with relatively higher speed and precision.

Doubled haploids have the great potential to enhance both breeding efficiency and genetic research in African marigold (Tagetes erecta L.). In order to obtain basic information about doubled haploids in African marigold, in the present study, we investigated the morphological characters in doubled haploids generated through anther culture. Screening of anther derived regenerants revealed that out of the 72 plants, 6 plants (8.33