Publications by authors named "Achla Sharma"

9 Publications

  • Page 1 of 1

Characterization and Mapping of Spot Blotch in Introgression Lines Using SNP Markers.

Front Plant Sci 2021 28;12:650400. Epub 2021 May 28.

School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, India.

Spot blotch (SB) of wheat is emerging as a major threat to successful wheat production in warm and humid areas of the world. SB, also called leaf blight, is caused by , and is responsible for high yield losses in Eastern Gangetic Plains Zone in India. More recently, SB is extending gradually toward cooler, traditional wheat-growing North-Western part of the country which is a major contributor to the national cereal basket. Deployment of resistant cultivars is considered as the most economical and ecologically sound measure to avoid losses due to this disease. In the present study, 89 backcross introgression lines (DSBILs) derived from (cv. PDW274-susceptible) × (resistant) were evaluated against SB for four consecutive years, 2016-2020. Phenotypic evaluation of these lines showed a continuous variation in disease severity indicating that the resistance to SB is certainly quantitative in nature. Phenotypic data of DSBILs were further used for mapping QTLs using SNPs obtained by genotyping by sequencing. To identify QTLs stable across the environments, Best Linear Unbiased Estimates (BLUEs) and Predictions (BLUPs) were used for mapping QTLs based on stepwise regression-based Likelihood Ratio Test (RSTEP-LRT) for additive effect of markers and single marker analysis (SMA). Five QTLs, , , , , and , linked to SB resistance were mapped across chromosomes 2A, 2B, 3B, 5B, and 6A. Genes found adjacent to the SNP markers linked to these QTLs were literature mined to identify possible candidate genes by studying their role in plant pathogenesis. Further, highly resistant DSBIL (DSBIL-13) was selected to cross with a susceptible hexaploidy cultivar (HD3086) generating BCF population. The QTL , linked to SNP S5B_703858864, was validated on this BCF population and thus, may prove to be a potential diagnostic marker for SB resistance.
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http://dx.doi.org/10.3389/fpls.2021.650400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8193842PMC
May 2021

Introgression and genetic mapping of leaf rust and stripe rust resistance in .

J Genet 2021 ;100

School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana 141 004, India.

The growing and cultivating resistant wheat crop varieties is important to meet the demands of the growing population and minimizing the yield losses due to foliar diseases. More important is the identification of novel resistance sources and transfer of resistance in ready to use form. In the current study, leaf rust (LR) and stripe rust (YR) resistant tetraploid nonprogenitors of wheat (UUCC) acc pau 3462 was crossed and backcrossed susceptible cultivar WL711(NN) by inducing homeologous pairing using CS ph1. Recurrent parent type plants were selected in subsequent generation with resistance to LR and YR and BCF introgression line (2=42) named have been developed. To understand the nature and inheritance of LR and YR resistance genes and to map their genomic location, F and F mapping populations were developed by crossing with WL711(NN). In F and F, the seedlings and adult plants segregated into 3R:1S and 1HR:2Seg:1HS ratios, respectively for both LR and YR, indicating inheritance of single dominant all stage resistance gene working against both the rusts. These genes were temporary designated as and and were inherited independently.Molecular mapping of 614 SSR markers mapped the at a distance of 11.2 cM from SSR marker .
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January 2021

Resurrection of Wheat Cultivar PBW343 Using Marker-Assisted Gene Pyramiding for Rust Resistance.

Front Plant Sci 2021 11;12:570408. Epub 2021 Feb 11.

Indian Institute of Wheat & Barley Research, Karnal, India.

Wheat variety PBW343, released in India in 1995, became the most widely grown cultivar in the country by the year 2000 owing to its wide adaptability and yield potential. It initially succumbed to leaf rust, and resistance genes and were transferred to PBW343. After an unbroken reign of about 10 years, the virulence against gene made PBW343 susceptible to stripe rust. Owing to its wide adaptability and yield potential, PBW343 became the prime target for marker-assisted introgression of stripe rust resistance genes. The leaf rust-resistant versions formed the base for pyramiding stripe rust resistance genes , and , in different introgression programs. Advanced breeding lines with different gene combinations, PBW665, PBW683, PBW698, and PBW703 were tested in national trials but could not be released as varieties. The genes from alien segments, () and (), were later pyramided in PBW343. Modified marker-assisted backcross breeding was performed, and 81.57% of the genetic background was recovered in one of the selected derivative lines, PBW723. This line was evaluated in coordinated national trials and was released for cultivation under timely sown irrigated conditions in the North Western Plain Zone of India. PBW723 yields an average of 58.0 qtl/ha in Punjab with high potential yields. The genes incorporated are susceptible to stripe rust individually, but PBW723 with both genes showed enhanced resistance. Three years post-release, PBW723 occupies approximately 8-9% of the cultivated area in the Punjab state. A regular inflow of diverse resistant genes, their rapid mobilization to most productive backgrounds, and keeping a close eye on pathogen evolution is essential to protect the overall progress for productivity and resistance in wheat breeding, thus helping breeders to keep pace with pathogen evolution.
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http://dx.doi.org/10.3389/fpls.2021.570408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7905314PMC
February 2021

Pyramiding of High Grain Weight With Stripe Rust and Leaf Rust Resistance in Elite Indian Wheat Cultivar Using a Combination of Marker Assisted and Phenotypic Selection.

Front Genet 2020 22;11:593426. Epub 2020 Dec 22.

School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, India.

Wheat ( L.) is an important cereal crop globally as well as in India and yield improvement programs encounter a strong impediment from ever-evolving rust pathogens. Hence, durable rust resistance is always a priority trait for wheat breeders globally. Grain weight, represented as thousand grain weight (TGW), is the most important yield-contributing trait in wheat. In the present study high TGW has been transferred into two elite Indian wheat cultivars PBW343 and PBW550 from a high TGW genotype, Rye selection 111, selected from local germplasm. In the background of PBW343 and PBW550, an increase in TGW upto 27.34 and 18% was observed, respectively (with respect to recipient parents), through conventional backcross breeding with phenotypic selections in 3 years replicated RBD trials. Resistance to leaf rust and stripe rust has been incorporated in the high TGW version of PBW550 through marker assisted pyramiding of stripe rust resistance gene using marker , and a pair of linked leaf rust and stripe rust resistance genes using marker . Improved versions of PBW550 with increased TGW ranging from 45.0 to 46.2 g (up to a 9% increase) and stacked genes for stripe and leaf rust resistance have been developed. This study serves as proof of utilizing conventional breeding and phenotypic selection combined with modern marker assisted selection in improvement of important wheat cultivars as a symbiont of conventional and moderan techniques.
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http://dx.doi.org/10.3389/fgene.2020.593426DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783403PMC
December 2020

Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security.

Sci Rep 2018 08 21;8(1):12527. Epub 2018 Aug 21.

ICAR-Indian Agricultural Research Institute, Regional Station, Shimla, 171004, India.

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the 'T' allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT's best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios.
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http://dx.doi.org/10.1038/s41598-018-30667-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6104032PMC
August 2018

Rht8 gene as an alternate dwarfing gene in elite Indian spring wheat cultivars.

PLoS One 2018 21;13(6):e0199330. Epub 2018 Jun 21.

Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab, India.

Optimizing wheat height to maximize yield has been an important aspect which is evident from a successful example of green revolution. Dwarfing genes (Rht) are known for yield gains due to lodging resistance and partitioning of assimilates into ear. The available and commercially exploited sources of dwarfism in Indian spring wheat are Rht1 and Rht2 genes inspite of availability of over 20 dwarfing genes. Rht8 a Gibberellic acid sensitive dwarfing gene is another reduced height gene commercially exploited in some Mediterranean countries. Two F2 populations segregating for Rht1 and Rht8 genes with each comprising 398 and 379 plants were developed by crossing European winter wheat cultivars Beauchamp and Capitole with Indian spring wheat cultivar PBW 621. Different genotypic combinations for Rht1 and Rht8 genes were selected from these populations through linked molecular markers and selected F3:4 lines were evaluated for various agronomic traits in a replicated trial. Reduction in plant height with Rht8 and Rht1 averaged 2.86% and 13.3% respectively as compared to the group of lines lacking dwarfing gene. Reduction was spread along all the internodes of wheat culm and reduction was lower as progress towards the lower internode. Grain number per spike and highest yield was observed in lines carrying only Rht1 gene. Reduction in plant biomass was observed with either of the dwarfing gene. Longest coleoptile length and seedling shoot length averaged 4.4 ± 0.09 cm and 19.5 ± 0.48, respectively was observed in lines lacking any of the dwarfing gene. Negligible reduction of 6.75% and 2.84% in coleoptile length and seedling shoot length, respectively was observed in lines carrying only Rht8 gene whereas F3:4 lines with Rht1 gene showed 21.64% and 23.35% reduction in coleoptile length and seedling shoot length, respectively. Additive effect of genes was observed as double dwarfs showed 43.31% and 43.34% reduction in coleoptile length and seedling shoot length.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199330PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6013103PMC
April 2019

Unlocking the genetic diversity of Creole wheats.

Sci Rep 2016 03 15;6:23092. Epub 2016 Mar 15.

International Maize and Wheat Improvement Center (CIMMYT), Apdo. Postal 6-641, 06600, Mexico DF, Mexico.

Climate change and slow yield gains pose a major threat to global wheat production. Underutilized genetic resources including landraces and wild relatives are key elements for developing high-yielding and climate-resilient wheat varieties. Landraces introduced into Mexico from Europe, also known as Creole wheats, are adapted to a wide range of climatic regimes and represent a unique genetic resource. Eight thousand four hundred and sixteen wheat landraces representing all dimensions of Mexico were characterized through genotyping-by-sequencing technology. Results revealed sub-groups adapted to specific environments of Mexico. Broadly, accessions from north and south of Mexico showed considerable genetic differentiation. However, a large percentage of landrace accessions were genetically very close, although belonged to different regions most likely due to the recent (nearly five centuries before) introduction of wheat in Mexico. Some of the groups adapted to extreme environments and accumulated high number of rare alleles. Core reference sets were assembled simultaneously using multiple variables, capturing 89% of the rare alleles present in the complete set. Genetic information about Mexican wheat landraces and core reference set can be effectively utilized in next generation wheat varietal improvement.
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http://dx.doi.org/10.1038/srep23092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791556PMC
March 2016

Differential response of wild and cultivated wheats to water deficits during grain development: changes in soluble carbohydrates and invertases.

Physiol Mol Biol Plants 2015 Apr 14;21(2):169-77. Epub 2015 Mar 14.

Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, 141004 India.

Wheat, staple food crop of the world, is sensitive to drought, especially during the grain-filling period. Water soluble carbohydrates (WSCs), stem reserve mobilization and higher invertase activity in the developing grains are important biochemical traits for breeding wheat to enhance tolerance to terminal drought. These traits were studied for three accessions of Triticum dicoccoides(a tetraploid wheat progenitor species) - acc 7054 (EC 171812), acc 7079 (EC 171837) and acc 14004 (G-194-3 M-6 M) selected previously on the basis of grain filling characteristics. Check wheat cultivars- PBW-343 (a popular bread wheat cultivar for irrigated environments) and C-306 (widely adapted variety for rain-fed agriculture) were also included in this set. Analysis of variance revealed significant genotypic differences for the content of water soluble carbohydrates, activity of acid invertase and alkaline invertase. Acc 7079 was found to be a very efficient mobilizer of water soluble carbohydrates (236.43 mg g(-1) peduncle DW) when averaged over irrigated and rain-fed conditions. Acid invertase activity revealed marked genotypic differences between wild and cultivated wheats. Alkaline invertase activity was highest in Acc 7079 when pooled across both the environments. On the whole, acc 7079 qualifies as a suitable donor for enhancing tolerance of bread wheat to terminal drought. The association of physio-biochemical differences observed with grain filling attributes on one hand and molecular markers on the other could be of use in improving wheat for water stress conditions.
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http://dx.doi.org/10.1007/s12298-015-0283-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4411390PMC
April 2015