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Guijun Yan - One of the best experts on this subject based on the ideXlab platform.
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comparative transcriptome analyses for Metribuzin tolerance provide insights into key genes and mechanisms restoring photosynthetic efficiency in bread wheat triticum aestivum l
Genomics, 2021Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Guijun YanAbstract:Abstract Weeds are the biggest threat to cropping system sustainability in wheat. Metribuzin is a versatile herbicide for broad-spectrum weed management. Understanding key genes, mechanisms and functional markers are essential to develop higher Metribuzin tolerant wheats. We identified Chuan Mai 25 (tolerant) and Ritchie (susceptible) as contrasting genotypes to Metribuzin stress through dose-response analyses. Transcriptome sequencing using NovaSeq 6000 RNA-Seq platform identified a total of 77,443 genes; 59,915 known genes and 17,528 novel genes. The functional enrichment analysis at 0 h, 24 h and 60 h herbicide exposure revealed that endogenous increase of metabolic enzymes, light-harvesting chlorophyll proteins, PSII stability factor HCF136 and glucose metabolism conferred Metribuzin tolerance. The validation of DEGs using RT-qPCR and QTL mapping confirmed their responsiveness to Metribuzin. Transcription factors MYB, AP2-EREBP, ABI3VP1, bHLH, NAC are significantly expressed during Metribuzin stress. Transcripts with significant enrichments revealed 114 SSRs for genomic selection . The master regulators provide promising avenues for enhancing Metribuzin tolerance.
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inheritance of pre emergent Metribuzin tolerance and putative gene discovery through high throughput snp array in wheat triticum aestivum l
BMC Plant Biology, 2019Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Hui Liu, Guijun YanAbstract:Herbicide tolerance is an important trait that allows effective weed management in wheat crops in dryland farming. Genetic knowledge of Metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we investigated gene effects for Metribuzin tolerance in nine crosses of wheat by partitioning the means and variances of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of this trait. Metribuzin tolerance was measured by a visual senescence score 21 days after treatment. The wheat 90 K iSelect SNP genotyping assay was used to identify the distribution of alleles at SNP sites in tolerant and susceptible groups. The scaling and joint-scaling tests indicated that the inheritance of Metribuzin tolerance in wheat was adequately described by the additive-dominance model, with additive gene action the most significant factor for tolerance. The potence ratio for all the crosses ranged between − 1 and + 1 for senescence under Metribuzin-treated conditions indicating a semi-dominant gene action in the inheritance of Metribuzin tolerance in wheat. The number of segregating genes governing Metribuzin tolerance was estimated between 3 and 15. The consistent high heritability range (0.82 to 0.92) in F5–7 generations of Chuan Mai 25 (tolerant) × Ritchie (susceptible) cross indicated a significant contribution of additive genetic effects to Metribuzin tolerance in wheat. Several genes related to photosynthesis (e.g. photosynthesis system II assembly factor YCF48), metabolic detoxification of xenobiotics and cell growth and development (cytochrome P450, glutathione S-transferase, glycosyltransferase, ATP-binding cassette transporters and glutathione peroxidase) were identified on different chromosomes (2A, 2D, 3B, 4A, 4B, 7A, 7B, 7D) governing Metribuzin tolerance. The simple additive–dominance gene effects for Metribuzin tolerance will help breeders to select tolerant lines in early generations and the identified genes may guide the development of functional markers for Metribuzin tolerance.
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identification of new Metribuzin tolerant wheat triticum spp genotypes
Crop & Pasture Science, 2017Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Katia Stefanova, Guijun YanAbstract:Herbicide-tolerant wheats are preferred for effective weed management. Rapid phenotyping and effective differential dose are vital for the identification of tolerant genotypes among large quantities of genetic resources. A sand-tray system has been developed to enable rapid assessment of Metribuzin damage in wheat seedlings. In total, 946 wheat genotypes were evaluated for Metribuzin tolerance by using this system under control and Metribuzin-treated conditions. SPAD chlorophyll content index (CCI) offered a non-destructive and rapid analysis of leaf chlorophyll content in wheat seedlings. The application rate for 50% reduction in SPAD CCI (I 50) was 3.2-fold higher in the current tolerant genotype (Eagle Rock) than the susceptible genotype Spear. A confirmed dose of 800 g a.i. ha–1 could differentiate between Metribuzin-tolerant and -susceptible lines. The experimental design with two-directional blocking followed by statistical analysis to model the spatial variation was instrumental in selecting potential tolerant or susceptible genotypes. Metribuzin reduced chlorophyll by 51.4% in treated seedlings. The overall adjusted mean SPAD CCI ranged from 13.5 to 42.7 for control (untreated) plants and from 0.1 to 29.9 for treated plants. Through repeated validation, nine genotypes had higher chlorophyll content after Metribuzin treatment and significantly (P < 0.05) outperformed the tolerant Eagle Rock, whereas 18 genotypes had significantly (P < 0.05) higher chlorophyll reduction than the susceptible Spear. The top five tolerant and susceptible genotypes were selected for a genetic study of Metribuzin tolerance. Domesticated forms of tetraploid and hexaploid wheats had higher tolerance to Metribuzin, which suggests that the level of domestication and higher ploidy level contributes to Metribuzin tolerance. The new sources of tolerance will accelerate breeding for Metribuzin tolerance.
Neera Singh - One of the best experts on this subject based on the ideXlab platform.
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Effect of fly ash amendment on persistence of Metribuzin in soils.
Journal of environmental science and health. Part. B Pesticides food contaminants and agricultural wastes, 2013Co-Authors: Neera Singh, Raunaq, Shashi Bala SinghAbstract:This study reports the effect of fly ash amendment on persistence of Metribuzin in three Indian soil types. Fly ash [Inderprastha (IP) and Kota] was amended at 1, 2 and 5% levels. Metribuzin was more persistent in the flooded soils (predominantly anaerobic) than the nonflooded (aerobic) soils. Kota fly ash amendment to nonflooded soils slightly enhanced Metribuzin persistence while IP fly ash reduced the herbicide persistence in nonflooded soils. In flooded soils both types of fly ash reduced Metribuzin persistence, but the extent of the effect was specific to the soil and type of fly ash. A better effect was observed in low organic matter soils and IP fly ash was more effective than the Kota fly ash. The effect of fly ash amendment on Metribuzin degradation in soils was more pronounced at higher dose of fly ash. No degradation of Metribuzin was observed in the sterilized soils, both without and with fly ash, suggesting that degradation of Metribuzin was microbial in nature. DeaminoMetribuzin was recovere...
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Reduced downward mobility of Metribuzin in fly ash-amended soils.
Journal of environmental science and health. Part. B Pesticides food contaminants and agricultural wastes, 2013Co-Authors: Neera Singh, Raunaq, Shashi Bala SinghAbstract:Metribuzin, a triazine herbicide, is poorly sorbed in the soils, therefore leaches to lower soil profile. Fly ash amendment, which enhanced Metribuzin sorption in soils, may play a significant role in reducing the downward mobility of herbicide. Therefore, the present study reports the effect of Inderprastha fly ash amendment on Metribuzin leaching in three soil types. Fly ash was amended at 1, 2 and 5% levels in the upper 15 cm of 30 cm long packed soil columns. Results suggested a significant reduction in the leaching losses of Metribuzin in fly ash-amended columns of all the three soil types and effect increased with increase in the level of fly ash. Even after percolating water equivalent to 362 mm rainfall no Metribuzin was recovered in the leachate of 5% fly ash-amended columns. Fly ash application affected both Metribuzin breakthrough time and its maximum concentration in the leachate. Further, it resulted in greater retention of Metribuzin in the application zone and better effect was observed in ...
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Effect of fly ash on sorption behavior of Metribuzin in agricultural soils
Journal of environmental science and health. Part. B Pesticides food contaminants and agricultural wastes, 2012Co-Authors: Neera Singh, Raunaq, Shashi Bala SinghAbstract:This investigation was undertaken to determine the effect of two different fly ashes [Kota and Inderprastha (IP)] amendment on the sorption behavior of Metribuzin in three Indian soil types. The IP fly ash was very effective in increasing the Metribuzin sorption in the soils. The sorption with IP amendment was increased by 15–92%, whereas with the Kota fly ash an increase in sorption by 13–38% was noted. The adsorption isotherms fitted very well to the Freundlich adsorption equation and, in general, slope (1/n) values less then unity were observed. Although both the fly ashes significantly decreased Metribuzin desorption, the IP fly ash was comparatively more effective in retaining Metribuzin in the soils. Metribuzin sorption in the IP fly ash-amended soils showed strong correlation with the fly ash content and compared to Kf/Kd values, KFA values (sorption normalized to fly ash content) showed less variation. Metribuzin sorption-desorption did not correlate to the organic carbon content of the soil-fly a...
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biocompost from sugar distillery effluent effect on Metribuzin degradation sorption and mobility
Pest Management Science, 2008Co-Authors: Neera SinghAbstract:BACKGROUND: Metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one) is weakly sorbed in soils and therefore leaches easily to lower soil profiles and results in loss of activity. Soil amendments play an important role in the management of runoff and leaching losses of pesticides from agricultural fields. Therefore, the effect of biocompost from sugarcane distillery effluent on Metribuzin degradation and mobility was studied in a sandy loam soil. RESULTS: Metribuzin was more persistent in biocompost-unamended (T-0) flooded soil (t1/2 − 41.2 days) than in non-flooded (t1/2 − 33.4 days) soil. Biocompost application at the rate of 2.5 and 5.0% (T-1 and T-2) in non-flooded soils increased Metribuzin persistence, but no significant effect was observed on persistence in flooded soils. Freundlich adsorption constants (Kf) for treatments T-0, T-1 and T-2 were 0.43, 0.64 and 1.13 respectively, suggesting that biocompost application caused increased Metribuzin sorption. Leaching studies in packed soil columns indicated that biocompost application affected both Metribuzin breakthrough time and maximum concentration in the leachate. Leaching losses of Metribuzin were drastically reduced from 93% in control soil (T-0) to 65% (T-1) and 31% (T-2) in biocompost-amended soils. CONCLUSION: Biocompost from sugarcane distillery effluent can be used effectively to reduce downward mobility of Metribuzin in low-organic-matter sandy loam soil. Copyright © 2008 Society of Chemical Industry
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effect of soil amendments on sorption and mobility of Metribuzin in soils
Chemosphere, 2007Co-Authors: Kaushik Majumdar, Neera SinghAbstract:Abstract Metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one), is weakly sorbed to soil therefore, leaches easily to lower soil profiles. Soil amendments play a significant role in the management of leaching losses of pesticides. Therefore, present study reports the effect of organic manure and fly ash amendments on Metribuzin downward mobility in sandy loam soil columns. Application of animal manure [T-1(OM) and T-2(OM)] and fly ash [T-1(FA) and T-2(FA)] at 2.5% and 5.0% levels increased the Metribuzin retention in the soil. Freundlich constant [Kf(1/n)] values of Metribuzin for treatments T-1(OM) and T-2(OM) were 0.70 and 1.11, respectively, which were significantly higher than the value (0.27) in natural soil (T-0). The respective values for treatments T-1(FA) and T-2(FA) were 1.80 and 4.61. Downward mobility of Metribuzin was studied in packed soil columns [300 mm (l) × 59 mm (i.d.)]. Both the amendments significantly reduced the downward mobility of Metribuzin and affected breakthrough time and maximum concentration of Metribuzin in the leachate. Leaching losses of Metribuzin were decreased from 97% in natural soil (T-0) column to 64% [T-1(OM)] and 42% [T-2(OM)] for animal manure-amended columns and 26% [T-1(FA)] to 100% [T-2(FA)] for fly ash-amended columns, as Metribuzin did not leach out of 5% fly ash-amended column. Study indicates that both animal manure and fly ash were quite effective in reducing the downward mobility of Metribuzin in packed soil columns of a sandy loam soil.
Roopali N Bhoite - One of the best experts on this subject based on the ideXlab platform.
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comparative transcriptome analyses for Metribuzin tolerance provide insights into key genes and mechanisms restoring photosynthetic efficiency in bread wheat triticum aestivum l
Genomics, 2021Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Guijun YanAbstract:Abstract Weeds are the biggest threat to cropping system sustainability in wheat. Metribuzin is a versatile herbicide for broad-spectrum weed management. Understanding key genes, mechanisms and functional markers are essential to develop higher Metribuzin tolerant wheats. We identified Chuan Mai 25 (tolerant) and Ritchie (susceptible) as contrasting genotypes to Metribuzin stress through dose-response analyses. Transcriptome sequencing using NovaSeq 6000 RNA-Seq platform identified a total of 77,443 genes; 59,915 known genes and 17,528 novel genes. The functional enrichment analysis at 0 h, 24 h and 60 h herbicide exposure revealed that endogenous increase of metabolic enzymes, light-harvesting chlorophyll proteins, PSII stability factor HCF136 and glucose metabolism conferred Metribuzin tolerance. The validation of DEGs using RT-qPCR and QTL mapping confirmed their responsiveness to Metribuzin. Transcription factors MYB, AP2-EREBP, ABI3VP1, bHLH, NAC are significantly expressed during Metribuzin stress. Transcripts with significant enrichments revealed 114 SSRs for genomic selection . The master regulators provide promising avenues for enhancing Metribuzin tolerance.
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inheritance of pre emergent Metribuzin tolerance and putative gene discovery through high throughput snp array in wheat triticum aestivum l
BMC Plant Biology, 2019Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Hui Liu, Guijun YanAbstract:Herbicide tolerance is an important trait that allows effective weed management in wheat crops in dryland farming. Genetic knowledge of Metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we investigated gene effects for Metribuzin tolerance in nine crosses of wheat by partitioning the means and variances of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of this trait. Metribuzin tolerance was measured by a visual senescence score 21 days after treatment. The wheat 90 K iSelect SNP genotyping assay was used to identify the distribution of alleles at SNP sites in tolerant and susceptible groups. The scaling and joint-scaling tests indicated that the inheritance of Metribuzin tolerance in wheat was adequately described by the additive-dominance model, with additive gene action the most significant factor for tolerance. The potence ratio for all the crosses ranged between − 1 and + 1 for senescence under Metribuzin-treated conditions indicating a semi-dominant gene action in the inheritance of Metribuzin tolerance in wheat. The number of segregating genes governing Metribuzin tolerance was estimated between 3 and 15. The consistent high heritability range (0.82 to 0.92) in F5–7 generations of Chuan Mai 25 (tolerant) × Ritchie (susceptible) cross indicated a significant contribution of additive genetic effects to Metribuzin tolerance in wheat. Several genes related to photosynthesis (e.g. photosynthesis system II assembly factor YCF48), metabolic detoxification of xenobiotics and cell growth and development (cytochrome P450, glutathione S-transferase, glycosyltransferase, ATP-binding cassette transporters and glutathione peroxidase) were identified on different chromosomes (2A, 2D, 3B, 4A, 4B, 7A, 7B, 7D) governing Metribuzin tolerance. The simple additive–dominance gene effects for Metribuzin tolerance will help breeders to select tolerant lines in early generations and the identified genes may guide the development of functional markers for Metribuzin tolerance.
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identification of new Metribuzin tolerant wheat triticum spp genotypes
Crop & Pasture Science, 2017Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Katia Stefanova, Guijun YanAbstract:Herbicide-tolerant wheats are preferred for effective weed management. Rapid phenotyping and effective differential dose are vital for the identification of tolerant genotypes among large quantities of genetic resources. A sand-tray system has been developed to enable rapid assessment of Metribuzin damage in wheat seedlings. In total, 946 wheat genotypes were evaluated for Metribuzin tolerance by using this system under control and Metribuzin-treated conditions. SPAD chlorophyll content index (CCI) offered a non-destructive and rapid analysis of leaf chlorophyll content in wheat seedlings. The application rate for 50% reduction in SPAD CCI (I 50) was 3.2-fold higher in the current tolerant genotype (Eagle Rock) than the susceptible genotype Spear. A confirmed dose of 800 g a.i. ha–1 could differentiate between Metribuzin-tolerant and -susceptible lines. The experimental design with two-directional blocking followed by statistical analysis to model the spatial variation was instrumental in selecting potential tolerant or susceptible genotypes. Metribuzin reduced chlorophyll by 51.4% in treated seedlings. The overall adjusted mean SPAD CCI ranged from 13.5 to 42.7 for control (untreated) plants and from 0.1 to 29.9 for treated plants. Through repeated validation, nine genotypes had higher chlorophyll content after Metribuzin treatment and significantly (P < 0.05) outperformed the tolerant Eagle Rock, whereas 18 genotypes had significantly (P < 0.05) higher chlorophyll reduction than the susceptible Spear. The top five tolerant and susceptible genotypes were selected for a genetic study of Metribuzin tolerance. Domesticated forms of tetraploid and hexaploid wheats had higher tolerance to Metribuzin, which suggests that the level of domestication and higher ploidy level contributes to Metribuzin tolerance. The new sources of tolerance will accelerate breeding for Metribuzin tolerance.
Josean Leite Pereira-barros - One of the best experts on this subject based on the ideXlab platform.
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AÇÃO DE ALGUNS PRODUTOS FITOSSANITÁRIOS PARA ADULTOS DE Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) Action of some phytossanitary products for Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) adults
Ciencia E Agrotecnologia, 2006Co-Authors: Sônia Maria Forti Broglio-micheletti, Adriano Jorge, Nunes Dos Santos, Josean Leite Pereira-barrosAbstract:RESUMOObjetivou-se com este trabalho avaliar em laboratorio, a 26±2°C; UR 60±10% e fotofase de 12 horas, a influencia doherbicida Metribuzin 480 SC, do inseticida quimico carbaril 480 SC, do fungo Metarhizium anisopliae (Metsch) Sorokin e dooleo emulsionavel de nim, Azadirachta indica A. Juss, sobre o parasitismo, a emergencia e a longevidade de Trichogrammagalloi Zucchi, 1988, criados em ovos de Diatraea saccharalis (Fabricius, 1794). Conduziu-se o ensaio utilizando-se 100posturas, obtidas em laboratorio, nas 24 horas apos a oviposicao, as quais foram tratadas por imersao e oferecidas aosparasitoides. O delineamento experimental foi inteiramente casualizado com dez tratamentos e dez repeticoes. O parasitismofoi prejudicado pelo nim nas concentracoes de 0,33; 0,53 e 1%, seguido pelo carbaril a 4%, metribuzim a 2,14% e M. anisopliae(IPA 159E) a 0,4%. A emergencia do parasitoide foi reduzida quando se utilizou o carbaril, M. anisopliae (IPA 159E) emetribuzim e, a longevidade foi afetada quando se empregou metribuzim e M. anisopliae (IPA 159E) com uma variacao mediamenor que 24 horas.Termos para indexacao: Produto fitossanitario, broca-da-cana-de-acucar, Trichogramma, Metarhizium anisopliae.ABSTRACTThe objective was to evaluate, in laboratory, at 26°C, UR 60±10% and 12 hours photophase, the influence of herbicideMetribuzin 480 SC, the chemical insecticide carbaryl 480 SC, the entomophatogen Metarhizium anisopliae (Metsch) Sorokin andemulsionable neem oil, Azadirachta indica A. Juss, on the parasitism, emergency and longevity of Trichogramma galloi Zucchi, 1988,reared in eggs of Diatraea saccharalis (Fabricius, 1794). The bioassay was conducted using one hundred postures, from laboratoryrearing, in the 24 hours after oviposition, which were treated by immersion and offered to the natural enemies. The experimentaldesign was entirely randomized with ten treatments and ten repetitions. The parasitism was harmed by neem in the concentrations(0.33, 0.53 and 1%), followed for carbaryl 4%, metribuzim 2.14% and M. anisopliae (IPA 159E) 0.4%. The emergency of theparasitoid was reduced for the treatments: carbaryl, M. anisopliae (IPA 159E) and metribuzim, and the longevity for metribuzim andM. anisopliae (IPA 159E) with an average variation lower that 24 hours.Index terms: Phytossanitary product, sugarcane borer, Trichogramma, Metarhizium anisopliae.(Recebido para publicacao em 9 de agosto de 2005 e aprovado 22 de maio de 2006)
Kadambot H M Siddique - One of the best experts on this subject based on the ideXlab platform.
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comparative transcriptome analyses for Metribuzin tolerance provide insights into key genes and mechanisms restoring photosynthetic efficiency in bread wheat triticum aestivum l
Genomics, 2021Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Guijun YanAbstract:Abstract Weeds are the biggest threat to cropping system sustainability in wheat. Metribuzin is a versatile herbicide for broad-spectrum weed management. Understanding key genes, mechanisms and functional markers are essential to develop higher Metribuzin tolerant wheats. We identified Chuan Mai 25 (tolerant) and Ritchie (susceptible) as contrasting genotypes to Metribuzin stress through dose-response analyses. Transcriptome sequencing using NovaSeq 6000 RNA-Seq platform identified a total of 77,443 genes; 59,915 known genes and 17,528 novel genes. The functional enrichment analysis at 0 h, 24 h and 60 h herbicide exposure revealed that endogenous increase of metabolic enzymes, light-harvesting chlorophyll proteins, PSII stability factor HCF136 and glucose metabolism conferred Metribuzin tolerance. The validation of DEGs using RT-qPCR and QTL mapping confirmed their responsiveness to Metribuzin. Transcription factors MYB, AP2-EREBP, ABI3VP1, bHLH, NAC are significantly expressed during Metribuzin stress. Transcripts with significant enrichments revealed 114 SSRs for genomic selection . The master regulators provide promising avenues for enhancing Metribuzin tolerance.
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inheritance of pre emergent Metribuzin tolerance and putative gene discovery through high throughput snp array in wheat triticum aestivum l
BMC Plant Biology, 2019Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Hui Liu, Guijun YanAbstract:Herbicide tolerance is an important trait that allows effective weed management in wheat crops in dryland farming. Genetic knowledge of Metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we investigated gene effects for Metribuzin tolerance in nine crosses of wheat by partitioning the means and variances of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of this trait. Metribuzin tolerance was measured by a visual senescence score 21 days after treatment. The wheat 90 K iSelect SNP genotyping assay was used to identify the distribution of alleles at SNP sites in tolerant and susceptible groups. The scaling and joint-scaling tests indicated that the inheritance of Metribuzin tolerance in wheat was adequately described by the additive-dominance model, with additive gene action the most significant factor for tolerance. The potence ratio for all the crosses ranged between − 1 and + 1 for senescence under Metribuzin-treated conditions indicating a semi-dominant gene action in the inheritance of Metribuzin tolerance in wheat. The number of segregating genes governing Metribuzin tolerance was estimated between 3 and 15. The consistent high heritability range (0.82 to 0.92) in F5–7 generations of Chuan Mai 25 (tolerant) × Ritchie (susceptible) cross indicated a significant contribution of additive genetic effects to Metribuzin tolerance in wheat. Several genes related to photosynthesis (e.g. photosynthesis system II assembly factor YCF48), metabolic detoxification of xenobiotics and cell growth and development (cytochrome P450, glutathione S-transferase, glycosyltransferase, ATP-binding cassette transporters and glutathione peroxidase) were identified on different chromosomes (2A, 2D, 3B, 4A, 4B, 7A, 7B, 7D) governing Metribuzin tolerance. The simple additive–dominance gene effects for Metribuzin tolerance will help breeders to select tolerant lines in early generations and the identified genes may guide the development of functional markers for Metribuzin tolerance.
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identification of new Metribuzin tolerant wheat triticum spp genotypes
Crop & Pasture Science, 2017Co-Authors: Roopali N Bhoite, Kadambot H M Siddique, Katia Stefanova, Guijun YanAbstract:Herbicide-tolerant wheats are preferred for effective weed management. Rapid phenotyping and effective differential dose are vital for the identification of tolerant genotypes among large quantities of genetic resources. A sand-tray system has been developed to enable rapid assessment of Metribuzin damage in wheat seedlings. In total, 946 wheat genotypes were evaluated for Metribuzin tolerance by using this system under control and Metribuzin-treated conditions. SPAD chlorophyll content index (CCI) offered a non-destructive and rapid analysis of leaf chlorophyll content in wheat seedlings. The application rate for 50% reduction in SPAD CCI (I 50) was 3.2-fold higher in the current tolerant genotype (Eagle Rock) than the susceptible genotype Spear. A confirmed dose of 800 g a.i. ha–1 could differentiate between Metribuzin-tolerant and -susceptible lines. The experimental design with two-directional blocking followed by statistical analysis to model the spatial variation was instrumental in selecting potential tolerant or susceptible genotypes. Metribuzin reduced chlorophyll by 51.4% in treated seedlings. The overall adjusted mean SPAD CCI ranged from 13.5 to 42.7 for control (untreated) plants and from 0.1 to 29.9 for treated plants. Through repeated validation, nine genotypes had higher chlorophyll content after Metribuzin treatment and significantly (P < 0.05) outperformed the tolerant Eagle Rock, whereas 18 genotypes had significantly (P < 0.05) higher chlorophyll reduction than the susceptible Spear. The top five tolerant and susceptible genotypes were selected for a genetic study of Metribuzin tolerance. Domesticated forms of tetraploid and hexaploid wheats had higher tolerance to Metribuzin, which suggests that the level of domestication and higher ploidy level contributes to Metribuzin tolerance. The new sources of tolerance will accelerate breeding for Metribuzin tolerance.
