Publications by authors named "Halil Toktay"

4 Publications

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A GWAS to identify the cereal cyst nematode (Heterodera filipjevi) resistance loci in diverse wheat prebreeding lines.

J Appl Genet 2021 Feb 6;62(1):93-98. Epub 2021 Jan 6.

Geneshifters, 222 Mary Jena Lane, Pullman, WA, 99163, USA.

Yield losses because of cereal cyst nematodes could be as high as 92%, causing a bottleneck for wheat production. An integrated approach (application of pesticides, crop rotation, and use of host resistance) is needed to manage this devastating pathogen where resistant cultivars are considered most effective. This necessitates the identification of nematode-resistant sources in the available germplasm. Here, we report on the genetic mapping of nematode resistance in 255 diverse prebreeding lines (PBLs) employing an association mapping strategy. Altogether, seven additive quantitative trait loci (QTL) were identified on chromosomes 1A, 2A, 2B, 2D, 3A, 6B, and 6D explaining a maximum of 9.42% phenotypic variation where at least five QTL (on chromosomes 2A, 2B, 2D, 6B, and 6D) are located on the same chromosomes that harbor the already known nematode resistance genes. Resistant PBLs carried Aegilops squarrosa (436) in their pedigree which could be the possible source of positive alleles. To add to it, better yield performance of the identified nematode-resistant lines under stress conditions indicates that the germplasm can provide both nematode resistance and high-yielding cultivars.
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http://dx.doi.org/10.1007/s13353-020-00607-yDOI Listing
February 2021

Resistance to Cereal Cyst Nematodes in Wheat and Barley: An Emphasis on Classical and Modern Approaches.

Int J Mol Sci 2019 Jan 19;20(2). Epub 2019 Jan 19.

National Engineering Laboratory for Crop Molecular Breeding, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

Cereal cyst nematodes (CCNs) are among the most important nematode pests that limit production of small grain cereals like wheat and barley. These nematodes alone are estimated to reduce production of crops by 10% globally. This necessitates a huge enhancement of nematode resistance in cereal crops against CCNs. Nematode resistance in wheat and barley in combination with higher grain yields has been a preferential research area for cereal nematologists. This usually involved the targeted genetic exploitations through natural means of classical selection breeding of resistant genotypes and finding quantitative trait luci (QTLs) associated with resistance genes. These improvements were based on available genetic diversity among the crop plants. Recently, genome-wide association studies have widely been exploited to associate nematode resistance or susceptibility with particular regions of the genome. Use of biotechnological tools through the application of various transgenic strategies for enhancement of nematode resistance in various crop plants including wheat and barley had also been an important area of research. These modern approaches primarily include the use of gene silencing, exploitation of nematode effector genes, proteinase inhibitors, chemodisruptive peptides and a combination of one or more of these approaches. Furthermore, the perspective genome editing technologies including CRISPR-Cas9 could also be helpful for improving CCN resistance in wheat and barley. The information provided in this review will be helpful to enhance resistance against CCNs and will attract the attention of the scientific community towards this neglected area.
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http://dx.doi.org/10.3390/ijms20020432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6359373PMC
January 2019

Association analysis of resistance to cereal cyst nematodes () and root lesion nematodes ( and ) in CIMMYT advanced spring wheat lines for semi-arid conditions.

Breed Sci 2016 Dec 25;66(5):692-702. Epub 2016 Oct 25.

Grains Research & Development Corporation (GRDC) , 4/4 National Circuit Barton 2600 ACT , Australia.

To identify loci linked to nematode resistance genes, a total of 126 of CIMMYT advanced spring wheat lines adapted to semi-arid conditions were screened for resistance to , , and , of which 107 lines were genotyped with 1,310 DArT. Association of DArT markers with nematode response was analyzed using the general linear model. Results showed that 11 markers were associated with resistance to (pathotype Ha21), 25 markers with resistance to , and 9 significant markers were identified to be linked with resistance to . In this work we confirmed that chromosome 4A (~90-105 cM) can be a source of resistance to as has been recently reported. Other significant markers were also identified on chromosomal regions where no resistant genes have been reported for both nematodes species. These novel QTL were mapped to chromosomes 5A, 6A, and 7A for ; on chromosomes 1A, 1B, 3A, 3B, 6B, 7AS, and 7D for ; and on chromosomes 1D, 2A, and 5B for and represent potentially new loci linked to resistance that may be useful for selecting parents and deploying resistance into elite germplasm adapted to regions where nematodes are causing problem.
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http://dx.doi.org/10.1270/jsbbs.15158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5282747PMC
December 2016

Identification of common root-lesion nematode (Pratylenchus thornei Sher et Allen) loci in bread wheat.

Genome 2006 Oct;49(10):1319-23

Plant Protection Research Institute, 01321, Adana, Turkey.

Plant parasitic nematodes are a major biotic cause of wheat-yield loss in temperate wheat-growing regions. A major strategy to develop resistance to root-lesion nematodes (RLNs) in wheat is to assess and then exploit their natural genetic variation. This study examines RLN (Pratylenchus thornei) resistance in 1 Middle Eastern landrace (AUS4930 7.2) and 1 synthetic hexaploid wheat, CROC_1/AE. SQUARROSA (224)//OPATA (CROC), using F2 and F9 populations generated by crossing AUS4930 7.2 and CROC with the susceptible cultivar Pastor, and inoculating these crosses with P. thornei in greenhouse trials. Wheat microsatellite markers linked to previously identified quantitative trait loci (QTLs) for resistance to P. thornei and P. neglectus were used to screen both populations. In the AUS4930 7.2 x Pastor population, resistance loci on chromosomes 1B, 2B, and 6D were detected. Similarly, in the CROC x Pastor population, 2 resistance loci, located on chromosomes 1B and 3B, were identified. Interestingly, a resistance locus located on chromosome 6D was not detected. More detailed mapping is required in these 2 populations, developed using new RLN resistance sources, to determine whether the QTLs identified on these chromosomes are the same, are allelic, or are linked to different resistance loci from those previously identified, and to determine whether these 2 sources contain other novel resistance loci.
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http://dx.doi.org/10.1139/g06-090DOI Listing
October 2006