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Guiping Yan - One of the best experts on this subject based on the ideXlab platform.
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First Report of the New Root-Lesion Nematode Pratylenchus sp. on Soybean in North Dakota
Plant Disease, 2017Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Intiaz Amin Chowdhury, Zafar A. HandooAbstract:Root-Lesion Nematodes (RLN; Pratylenchus spp.) are important nematode pests on soybean (Glycine max (L.) Merr.). In May 2015 and 2016, sixtwo soil samples were collected from a soybean field in Walcott, Richland County, ND. Nematodes were extracted from soil using a sugar centrifugal flotation method., revealing these two All the samples contained RLN from 125 to 2, 000and 350 Root-Lesion Nematodes per kg soil, respectively. In 2016, four soil samples were collected from the same field and all the samples had Root-Lesion Nematodes ranging from 300 to 2,000. One soil sample with 350 RLN Lesion Nematodes per kg soil was planted withto soybean cultivar Barnes in four replicates each in a pot (6.4-cm × 25.4-cm) with 500 g soil(n = 4). After 15 weeks of growth at 22°C in a greenhouse room at 22°C, the Root-Lesion nematode RLN population was found to have increased greatly. The final population density in soil was 1,518 ± 541 Lesion NematodesRLN per kg soil. Soybean Roots were rinsed with water and brown Lesion...
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first report of the Root Lesion nematode pratylenchus neglectus on wheat triticum aestivum in north dakota
Plant Disease, 2016Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Zhaohui Liu, Venkataramana Chapara, Z. A. HandooAbstract:Root-Lesion Nematodes (Pratylenchus spp.) are important nematode pests that invade Roots of plants and restrict productivity of wheat (Smiley et al. 2005). In August 2015, a soil sample was collected from a harvested wheat field in Walsh County, ND, and was found to contain 1,044 Root-Lesion Nematodes per kg of soil using the sugar centrifugal flotation method. In October 2015, four soil samples were collected from the same field and had Root-Lesion Nematodes ranging from 125 to 1,000/kg soil. One soil sample with 500 Lesion Nematodes/kg soil was used to inoculate hard red spring wheat cvs. Glenn and Faller. After 10 weeks of growth in a greenhouse room maintained at 22°C, wheat Roots were harvested and washed, and light brown Lesions were observed on lateral Roots. The washed Roots were cut into 1-cm segments for nematode extraction using the Whitehead tray method. After 48 h, Lesion Nematodes were recovered from the Root tissues. Averages of 24 and 20 Root-Lesion Nematodes per gram were found in the Roots of Glenn and Faller, respectively. Nematodes from soil and wheat Roots were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 402.0 to 495.0 μm, mean = 446.0 μm), stylet (15.0 to 17.5, 16.4), tail length (16.0 to 22.0, 18.8), body width (17.0 to 22.0, 19.6), anterior end to basal bulb (90.0 to 115.0, 101.6), a = (21.2 to 24.7, 23.1), b = (3.7 to 4.8, 4.4), c = (19.6 to 27.1, 23.8), and V (81.0 to 85.0%, 82.8%). The lip region had two annules, and was not set off, with anterior margins of apical lip annule convex, second annule was slightly wider than the first; lateral field had four lines with central zone of lateral field having oblique striae; tail terminus was smooth, rounded, or slightly oblique. The nematode species was identified as Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941 based on morphological and morphometric characteristics (Castillo and Vovlas 2007). DNA was extracted from single Nematodes (n = 11) isolated from soil and wheat Roots, and ITS region of rDNA was amplified (Tanha Maafi et al. 2003). PCR products from three Nematodes were cloned using pGEM-T easy vector and sequenced, and the resulting ITS sequences were identical. The consensus sequence (GenBank Accession No. KU705392, 684 bp) was 99% homologous with one population of P. neglectus from China (JX046941) and 83% or less identical to other Pratylenchus spp. including P. thornei, a species closely related to P. neglectus. The specific primers from D3 28S rRNA and ITS rDNA were used to amplify DNA of eight Nematodes and produced single bands specific for P. neglectus (Yan et al. 2008, 2013). The combination of the molecular tests confirmed the target species as P. neglectus. Two species of Root-Lesion Nematodes, P. neglectus and P. thornei, were reported as damaging pathogens affecting wheat production in the Pacific Northwest (Smiley et al. 2005). To our knowledge, this is the first report of P. neglectus on wheat in North Dakota. The resistance levels of various wheat cultivars to this Lesion nematode are being identified.
Z. A. Handoo - One of the best experts on this subject based on the ideXlab platform.
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first report of the Root Lesion nematode pratylenchus neglectus on wheat triticum aestivum in north dakota
Plant Disease, 2016Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Zhaohui Liu, Venkataramana Chapara, Z. A. HandooAbstract:Root-Lesion Nematodes (Pratylenchus spp.) are important nematode pests that invade Roots of plants and restrict productivity of wheat (Smiley et al. 2005). In August 2015, a soil sample was collected from a harvested wheat field in Walsh County, ND, and was found to contain 1,044 Root-Lesion Nematodes per kg of soil using the sugar centrifugal flotation method. In October 2015, four soil samples were collected from the same field and had Root-Lesion Nematodes ranging from 125 to 1,000/kg soil. One soil sample with 500 Lesion Nematodes/kg soil was used to inoculate hard red spring wheat cvs. Glenn and Faller. After 10 weeks of growth in a greenhouse room maintained at 22°C, wheat Roots were harvested and washed, and light brown Lesions were observed on lateral Roots. The washed Roots were cut into 1-cm segments for nematode extraction using the Whitehead tray method. After 48 h, Lesion Nematodes were recovered from the Root tissues. Averages of 24 and 20 Root-Lesion Nematodes per gram were found in the Roots of Glenn and Faller, respectively. Nematodes from soil and wheat Roots were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 402.0 to 495.0 μm, mean = 446.0 μm), stylet (15.0 to 17.5, 16.4), tail length (16.0 to 22.0, 18.8), body width (17.0 to 22.0, 19.6), anterior end to basal bulb (90.0 to 115.0, 101.6), a = (21.2 to 24.7, 23.1), b = (3.7 to 4.8, 4.4), c = (19.6 to 27.1, 23.8), and V (81.0 to 85.0%, 82.8%). The lip region had two annules, and was not set off, with anterior margins of apical lip annule convex, second annule was slightly wider than the first; lateral field had four lines with central zone of lateral field having oblique striae; tail terminus was smooth, rounded, or slightly oblique. The nematode species was identified as Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941 based on morphological and morphometric characteristics (Castillo and Vovlas 2007). DNA was extracted from single Nematodes (n = 11) isolated from soil and wheat Roots, and ITS region of rDNA was amplified (Tanha Maafi et al. 2003). PCR products from three Nematodes were cloned using pGEM-T easy vector and sequenced, and the resulting ITS sequences were identical. The consensus sequence (GenBank Accession No. KU705392, 684 bp) was 99% homologous with one population of P. neglectus from China (JX046941) and 83% or less identical to other Pratylenchus spp. including P. thornei, a species closely related to P. neglectus. The specific primers from D3 28S rRNA and ITS rDNA were used to amplify DNA of eight Nematodes and produced single bands specific for P. neglectus (Yan et al. 2008, 2013). The combination of the molecular tests confirmed the target species as P. neglectus. Two species of Root-Lesion Nematodes, P. neglectus and P. thornei, were reported as damaging pathogens affecting wheat production in the Pacific Northwest (Smiley et al. 2005). To our knowledge, this is the first report of P. neglectus on wheat in North Dakota. The resistance levels of various wheat cultivars to this Lesion nematode are being identified.
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Occurrence, population density, and distribution of Root-Lesion Nematodes, Pratylenchus spp., in the Sultanate of Oman.
Nematropica, 1997Co-Authors: A. Mani, Muzna S. Al Hinai, Z. A. HandooAbstract:Surveys were conducted in Batinah, Dhahira, Interior, Jabal Akhdar, and Sharqia regions and Dhofar and Musandam governorates of the Sultanate of Oman during cropping seasons from 1990-97, to study the occurrence, population density, and distribution of Root-Lesion Nematodes. Twelve species of Pratylenchus were recorded in association with 31 plant families that included 21 vegetable crops, 19 tree fruit crops, 16 field crops, two ornamentals and 14 weeds. Eleven known species of Pratylenchus are reported in the country for the first time. Among them P. jordanensis was the most frequently observed nematode species occurring in association with 37 crops and 14 weed species and found widely distributed in all the regions. Pratylenchus neglectus was the second most frequently recorded species in association with 24 plant species. Pratylenchus brachyurus, P. coffeae, P. scribneri, and P. zeae were the other economically important nematode species observed in the country.
Addison Plaisance - One of the best experts on this subject based on the ideXlab platform.
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First Report of the New Root-Lesion Nematode Pratylenchus sp. on Soybean in North Dakota
Plant Disease, 2017Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Intiaz Amin Chowdhury, Zafar A. HandooAbstract:Root-Lesion Nematodes (RLN; Pratylenchus spp.) are important nematode pests on soybean (Glycine max (L.) Merr.). In May 2015 and 2016, sixtwo soil samples were collected from a soybean field in Walcott, Richland County, ND. Nematodes were extracted from soil using a sugar centrifugal flotation method., revealing these two All the samples contained RLN from 125 to 2, 000and 350 Root-Lesion Nematodes per kg soil, respectively. In 2016, four soil samples were collected from the same field and all the samples had Root-Lesion Nematodes ranging from 300 to 2,000. One soil sample with 350 RLN Lesion Nematodes per kg soil was planted withto soybean cultivar Barnes in four replicates each in a pot (6.4-cm × 25.4-cm) with 500 g soil(n = 4). After 15 weeks of growth at 22°C in a greenhouse room at 22°C, the Root-Lesion nematode RLN population was found to have increased greatly. The final population density in soil was 1,518 ± 541 Lesion NematodesRLN per kg soil. Soybean Roots were rinsed with water and brown Lesion...
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first report of the Root Lesion nematode pratylenchus neglectus on wheat triticum aestivum in north dakota
Plant Disease, 2016Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Zhaohui Liu, Venkataramana Chapara, Z. A. HandooAbstract:Root-Lesion Nematodes (Pratylenchus spp.) are important nematode pests that invade Roots of plants and restrict productivity of wheat (Smiley et al. 2005). In August 2015, a soil sample was collected from a harvested wheat field in Walsh County, ND, and was found to contain 1,044 Root-Lesion Nematodes per kg of soil using the sugar centrifugal flotation method. In October 2015, four soil samples were collected from the same field and had Root-Lesion Nematodes ranging from 125 to 1,000/kg soil. One soil sample with 500 Lesion Nematodes/kg soil was used to inoculate hard red spring wheat cvs. Glenn and Faller. After 10 weeks of growth in a greenhouse room maintained at 22°C, wheat Roots were harvested and washed, and light brown Lesions were observed on lateral Roots. The washed Roots were cut into 1-cm segments for nematode extraction using the Whitehead tray method. After 48 h, Lesion Nematodes were recovered from the Root tissues. Averages of 24 and 20 Root-Lesion Nematodes per gram were found in the Roots of Glenn and Faller, respectively. Nematodes from soil and wheat Roots were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 402.0 to 495.0 μm, mean = 446.0 μm), stylet (15.0 to 17.5, 16.4), tail length (16.0 to 22.0, 18.8), body width (17.0 to 22.0, 19.6), anterior end to basal bulb (90.0 to 115.0, 101.6), a = (21.2 to 24.7, 23.1), b = (3.7 to 4.8, 4.4), c = (19.6 to 27.1, 23.8), and V (81.0 to 85.0%, 82.8%). The lip region had two annules, and was not set off, with anterior margins of apical lip annule convex, second annule was slightly wider than the first; lateral field had four lines with central zone of lateral field having oblique striae; tail terminus was smooth, rounded, or slightly oblique. The nematode species was identified as Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941 based on morphological and morphometric characteristics (Castillo and Vovlas 2007). DNA was extracted from single Nematodes (n = 11) isolated from soil and wheat Roots, and ITS region of rDNA was amplified (Tanha Maafi et al. 2003). PCR products from three Nematodes were cloned using pGEM-T easy vector and sequenced, and the resulting ITS sequences were identical. The consensus sequence (GenBank Accession No. KU705392, 684 bp) was 99% homologous with one population of P. neglectus from China (JX046941) and 83% or less identical to other Pratylenchus spp. including P. thornei, a species closely related to P. neglectus. The specific primers from D3 28S rRNA and ITS rDNA were used to amplify DNA of eight Nematodes and produced single bands specific for P. neglectus (Yan et al. 2008, 2013). The combination of the molecular tests confirmed the target species as P. neglectus. Two species of Root-Lesion Nematodes, P. neglectus and P. thornei, were reported as damaging pathogens affecting wheat production in the Pacific Northwest (Smiley et al. 2005). To our knowledge, this is the first report of P. neglectus on wheat in North Dakota. The resistance levels of various wheat cultivars to this Lesion nematode are being identified.
Danqiong Huang - One of the best experts on this subject based on the ideXlab platform.
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First Report of the New Root-Lesion Nematode Pratylenchus sp. on Soybean in North Dakota
Plant Disease, 2017Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Intiaz Amin Chowdhury, Zafar A. HandooAbstract:Root-Lesion Nematodes (RLN; Pratylenchus spp.) are important nematode pests on soybean (Glycine max (L.) Merr.). In May 2015 and 2016, sixtwo soil samples were collected from a soybean field in Walcott, Richland County, ND. Nematodes were extracted from soil using a sugar centrifugal flotation method., revealing these two All the samples contained RLN from 125 to 2, 000and 350 Root-Lesion Nematodes per kg soil, respectively. In 2016, four soil samples were collected from the same field and all the samples had Root-Lesion Nematodes ranging from 300 to 2,000. One soil sample with 350 RLN Lesion Nematodes per kg soil was planted withto soybean cultivar Barnes in four replicates each in a pot (6.4-cm × 25.4-cm) with 500 g soil(n = 4). After 15 weeks of growth at 22°C in a greenhouse room at 22°C, the Root-Lesion nematode RLN population was found to have increased greatly. The final population density in soil was 1,518 ± 541 Lesion NematodesRLN per kg soil. Soybean Roots were rinsed with water and brown Lesion...
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first report of the Root Lesion nematode pratylenchus neglectus on wheat triticum aestivum in north dakota
Plant Disease, 2016Co-Authors: Guiping Yan, Addison Plaisance, Danqiong Huang, Zhaohui Liu, Venkataramana Chapara, Z. A. HandooAbstract:Root-Lesion Nematodes (Pratylenchus spp.) are important nematode pests that invade Roots of plants and restrict productivity of wheat (Smiley et al. 2005). In August 2015, a soil sample was collected from a harvested wheat field in Walsh County, ND, and was found to contain 1,044 Root-Lesion Nematodes per kg of soil using the sugar centrifugal flotation method. In October 2015, four soil samples were collected from the same field and had Root-Lesion Nematodes ranging from 125 to 1,000/kg soil. One soil sample with 500 Lesion Nematodes/kg soil was used to inoculate hard red spring wheat cvs. Glenn and Faller. After 10 weeks of growth in a greenhouse room maintained at 22°C, wheat Roots were harvested and washed, and light brown Lesions were observed on lateral Roots. The washed Roots were cut into 1-cm segments for nematode extraction using the Whitehead tray method. After 48 h, Lesion Nematodes were recovered from the Root tissues. Averages of 24 and 20 Root-Lesion Nematodes per gram were found in the Roots of Glenn and Faller, respectively. Nematodes from soil and wheat Roots were examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 10) included body length (range = 402.0 to 495.0 μm, mean = 446.0 μm), stylet (15.0 to 17.5, 16.4), tail length (16.0 to 22.0, 18.8), body width (17.0 to 22.0, 19.6), anterior end to basal bulb (90.0 to 115.0, 101.6), a = (21.2 to 24.7, 23.1), b = (3.7 to 4.8, 4.4), c = (19.6 to 27.1, 23.8), and V (81.0 to 85.0%, 82.8%). The lip region had two annules, and was not set off, with anterior margins of apical lip annule convex, second annule was slightly wider than the first; lateral field had four lines with central zone of lateral field having oblique striae; tail terminus was smooth, rounded, or slightly oblique. The nematode species was identified as Pratylenchus neglectus (Rensch, 1924) Filipjev & Schuurmans Stekhoven, 1941 based on morphological and morphometric characteristics (Castillo and Vovlas 2007). DNA was extracted from single Nematodes (n = 11) isolated from soil and wheat Roots, and ITS region of rDNA was amplified (Tanha Maafi et al. 2003). PCR products from three Nematodes were cloned using pGEM-T easy vector and sequenced, and the resulting ITS sequences were identical. The consensus sequence (GenBank Accession No. KU705392, 684 bp) was 99% homologous with one population of P. neglectus from China (JX046941) and 83% or less identical to other Pratylenchus spp. including P. thornei, a species closely related to P. neglectus. The specific primers from D3 28S rRNA and ITS rDNA were used to amplify DNA of eight Nematodes and produced single bands specific for P. neglectus (Yan et al. 2008, 2013). The combination of the molecular tests confirmed the target species as P. neglectus. Two species of Root-Lesion Nematodes, P. neglectus and P. thornei, were reported as damaging pathogens affecting wheat production in the Pacific Northwest (Smiley et al. 2005). To our knowledge, this is the first report of P. neglectus on wheat in North Dakota. The resistance levels of various wheat cultivars to this Lesion nematode are being identified.
J P Thompson - One of the best experts on this subject based on the ideXlab platform.
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cereal cultivars can be ranked consistently for resistance to Root Lesion Nematodes pratylenchus thornei p neglectus using diverse procedures
Australasian Plant Pathology, 2015Co-Authors: J. G. Sheedy, V A Vanstone, A Kelly, Alan Mckay, J Lewis, S Fletcher, J P ThompsonAbstract:The Root-Lesion Nematodes (RLN) Pratylenchus thornei and P. neglectus are widely distributed in Australian grain producing regions and can reduce the yield of intolerant wheat cultivars by up to 65 %, costing the industry ~123 M AUD/year. Consequently, researchers in the northern, southern and western regions have independently developed procedures to evaluate the resistance of cereal cultivars to RLN. To compare results, each of the three laboratories phenotyped a set of 26 and 36 cereal cultivars for relative resistance/susceptibility to P. thornei and P. neglectus respectively. The northern and southern regions also investigated the effects of planting time and experiment duration on RLN reproduction and cultivar ranking. Results show the genetic correlation between cultivars tested using the northern and southern procedures evaluating P. thornei resistance was 0.93. Genetic correlations between experiments using the same procedure, but with different planting times, were 0.99 for both northern and southern procedures. The genetic correlation between cultivars tested using the northern, southern and western procedures evaluating P. neglectus resistance ranged from 0.71 to 0.95. Genetic correlations between experiments using the same procedure but with different planting times ranged from 0.91 to 0.99. This study established that, even though experiments were conducted in different geographic locations and with different trial management practices, the diverse nematode resistance screening procedures ranked cultivars similarly. Consequently, RLN resistance data can be pooled across regions to provide national consensus ratings of cultivars.
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inheritance of resistance to Root Lesion Nematodes pratylenchus thornei and p neglectus in five doubled haploid populations of wheat
Euphytica, 2012Co-Authors: J P Thompson, R S Zwart, David G ButlerAbstract:Nematode species Pratylenchus thornei and P. neglectus are the two most important Root-Lesion Nematodes affecting wheat (Triticum aestivum L.) and other grain crops in Australia. For practical plant breeding, it will be valuable to know the mode of inheritance of resistance and whether the same set of genes confer resistance to both species. We evaluated reactions to P. thornei and P. neglectus of glasshouse-inoculated plants of five doubled-haploid populations derived from five resistant synthetic hexpaloid wheat lines, each crossed to the susceptible Australian wheat cultivar Janz. For each cross we determined genetic variance, heritability and minimum number of effective resistance genes for each nematode species. Distributions of nematode numbers for both species were continuous for all doubled-haploid populations. Heritabilities were high and the resistances were controlled by 4-7 genes. There was no genetic correlation between resistance to P. thornei and to P. neglectus in four of the populations and a significant but low correlation in one. Therefore, resistances to P. thornei and to P. neglectus are probably inherited quantitatively and independently in four of these synthetic hexaploid wheat populations, with the possibility of at least one genetic factor contributing to resistance to both species in one of the populations. Parents with the greatest level of resistance will be the best to use as donor parents to adapted cultivars, and selection of resistance to both species in early generations will be optimal to carry resistance through successive cycles of inbreeding to produce resistant cultivars for release.
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hybridisation of australian chickpea cultivars with wild cicer spp increases resistance to Root Lesion Nematodes pratylenchus thornei and p neglectus
Australasian Plant Pathology, 2011Co-Authors: J P Thompson, Beverley J. Gogel, T. G. Clewett, J. G. Sheedy, R A Reen, A Kelly, E J KnightsAbstract:Australian and international chickpea (Cicer arietinum) cultivars and germplasm accessions, and wild annual Cicer spp. in the primary and secondary gene pools, were assessed in glasshouse experiments for levels of resistance to the Root-Lesion Nematodes Pratylenchus thornei and P. neglectus. Lines were grown in replicated experiments in pasteurised soil inoculated with a pure culture of either P. thornei or P. neglectus and the population density of the Nematodes in the soil plus Roots after 16 weeks growth was used as a measure of resistance. Combined statistical analyses of experiments (nine for P. thornei and four for P. neglectus) were conducted and genotypes were assessed using best linear unbiased predictions. Australian and international chickpea cultivars possessed a similar range of susceptibilities through to partial resistance. Wild relatives from both the primary (C. reticulatum and C. echinospermum) and secondary (C. bijugum) gene pools of chickpea were generally more resistant than commercial chickpea cultivars to either P. thornei or P. neglectus or both. Wild relatives of chickpea have probably evolved to have resistance to endemic Root-Lesion Nematodes whereas modern chickpea cultivars constitute a narrower gene pool with respect to nematode resistance. Resistant accessions of C. reticulatum and C. echinospermum were crossed and topcrossed with desi chickpea cultivars and resistant F4 lines were obtained. Development of commercial cultivars with the high levels of resistance to P. thornei and P. neglectus in these hybrids will be most valuable for areas of the Australian grain region and other parts of the world where alternating chickpea and wheat crops are the preferred rotation.
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simultaneous selection of wheat plants with resistance to Root Lesion Nematodes crown rot and yellow spot
2011Co-Authors: J. G. Sheedy, J P Thompson, R A Reen, T. G. ClewettAbstract:Wheat is Australia’s largest grain crop with an annual value of $5 B with the northern grain region contributing around $883 M. Root Lesion Nematodes (RLN; Pratylenchus thornei [Pt] & P. neglectus [Pn]), crown rot (CR; Fusarium pseudograminearum) and yellow spot (YS; Pyrenophora tritici-repentis) are four economically important diseases that commonly occur in combination and cost the northern wheat industry $137 M annually. Therefore, there is a need to develop germplasm with combinations of disease resistance to minimise yield loss in these situations. To achieve this, the established screening methods for each disease were combined and where necessary modified (RLN: One plant grown in a pot with 330 g of pasteurised soil, inoculated with 1650 each of Pt and Pn at planting, soil harvested after 16 weeks and RLN extracted and counted; YS: spore suspension applied by aerosol sprayer to seedlings 7 days after planting [DAP] and rated on a 1 to 9 scale 18 DAP; CR: 10mL of liquid inoculum containing spores and hyphae applied at the plant base 7 DAP, leaf sheaths rated for percentage browning 21 DAP and 20mL/plant of Benomyl® [xx g/L] applied 3 times after rating), to allow testing of up to 4 diseases simultaneously. Initial experiments used up to 42 fixed cultivars covering resistant to susceptible reactions to each disease and a final experiment of 21 check cultivars and 132 F3’s from a CPI133872 x Janz double haploid (moderately resistant to Pt, Pn and YS) crossed to EGA Wylie (moderately resistant to CR) exposed to all 4 diseases simultaneously. YS reactions of fixed cultivars in multiple disease treatments were significantly correlated with the YS alone treatment (R2 up to 0.66***), as were CR treatments (R2 up to 0.48***). Similarly, the check cultivars in the F3 experiment were significantly correlated with long-term data for YS (R2 = 0.89***) and CR (R2 = 0.38**). RLN data has not been finalised but at least one F3 with resistance to all four diseases has been identified. These methods appear to have the potential to hasten the development of multiple-disease resistant parents, suitable for introduction into commercial breeding programs.
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resistance to Root Lesion Nematodes pratylenchus thornei and p neglectus in synthetic hexaploid wheats and their durum and aegilops tauschii parents
Crop & Pasture Science, 2008Co-Authors: J P ThompsonAbstract:Root-Lesion Nematodes (Pratylenchus thornei Sher and Allen and P. neglectus (Rensch) Filipijev and Schuurmans Stekhoven) cause substantial yield loss to wheat crops in the northern grain region of Australia. Resistance to P. thornei for use in wheat breeding programs was sought among synthetic hexaploid wheats (2n= 6x = 42, AABBDD) produced through hybridisations of Triticum turgidum L. subsp. durum (Desf.) Husn (2n= 4x = 28, AABB) with Aegilops tauschii Coss. (2n= 2x = 14, DD). Resistance was determined for the synthetic hexaploid wheats and their durum and Ae. tauschii parents from the numbers of Nematodes in the Roots of plants grown for 16 weeks in pots of pasteurised soil inoculated with P. thornei. Fifty-nine (32%) of 186 accessions of synthetic hexaploid wheats had lower numbers of Nematodes than Gatcher Selection 50a (GS50a), a partially resistant bread wheat. Greater frequencies of partial resistance were present in the durum parents (72% of 39 lines having lower nematode numbers than GS50a) and in the Ae. tauschii parents (55% of 53 lines). The 59 synthetic hexaploids were re-tested in a second experiment along with their parents. In a third experiment, 11 resistant synthetic hexaploid wheats and their F-1 hybrids with Janz, a susceptible bread wheat, were tested and the F(1)s were found to give nematode counts intermediate between the respective two parents. Synthetic hexaploid wheats with higher levels of resistance resulted from hybridisations where both the durum and Ae. tauschii parents were partially resistant, rather than where only one parent was partially resistant. These results suggest that resistance to P. thornei in synthetic hexaploid wheats is polygenic, with resistances located both in the D genome from Ae. tauschii and in the A and/or B genomes from durum. Five synthetic hexaploid wheats were selected for further study on the basis of (1) a high level of resistance to P. thornei of the synthetic hexaploid wheats and of both their durum and Ae. tauschii parents, (2) being representative of both Australian and CIMMYT (International Maize and Wheat Improvement Centre) durums, and (3) being representative of the morphological subspecies and varieties of Ae. tauschii. These 5 synthetic hexaploid wheats were also shown to be resistant to P. neglectus, whereas GS50a and 2 P. thornei-resistant derivatives were quite susceptible. Results of P. thornei resistance of F(1)s and F(2)s from a half diallel of these 5 synthetic hexaploid wheats, GS50a, and Janz from another study indicate polygenic additive resistance and better general combining ability for the synthetic hexaploid wheats than for GS50a. Published molecular marker studies on a doubled haploid population between the synthetic hexaploid wheat with best general combining ability (CPI133872) and Janz have shown quantitative trait loci for resistance located in all 3 genomes. Synthetic hexaploid wheats offer a convenient way of introgressing new resistances to P. thornei and P. neglectus from both durum and Ae. tauschii into commercial bread wheats.
