Occurrence of the rust resistance gene Lr37 from Aegilops ventricosa in Argentine cultivars of wheat

Leaf rust of wheat ( Triticum aestivum L.) caused by the fungus Puccinia triticina (formerly P. recondita f. sp. tritici), is one of the most important foliar diseases of this crop. Lr37 rust resistance gene, which confers resistance in wheat against leaf rust, was introgressed into cultivated wheat from Aegilops ventricosa Tausch. Rust races with virulence to Lr37 have been identified in different countries, but it still provides resistance to a wide range of races and is useful in combination with other resistance genes. There are no reports about the presence, frequency and origin of Lr37 in Argentinean wheat cultivars. In this work, we analyzed 88 registered Argentinean wheat cultivars developed by different breeding companies and institutions during the last 15 years by means of a molecular marker which is diagnostic of the 2NS-2AS translocation which carries Lr37. Only 4 cultivars showed the amplification product associated with this chromosome fragment. These four cultivars which carry the translocated 2NS-2AS chromosome were registered by the same breeding company during the last seven years and all of them have European germplasm in their genealogy. To the best of our knowledge this is the first report of the presence of Lr37 in registered South American cultivars

Contribution of non-target-site resistance in imidazolinone-resistant imisun sunflower

The first commercial herbicide-resistant trait in sunflower (Helianthus annuus L.) is known as ‘Imisun’. Imidazolinone resistance in Imisun cultivars has been reported to be genetically controlled by a major gene (known as Imr1 or Ahasl1-1) and modifier genes. Imr1 is an allelic variant of the Ahasl1 locus that codes for the acetohydroxyacid synthase, which is the target site of these herbicides. The mechanism of resistance endowed by modifier genes has not been characterized and it could be related to non-target-site resistance. The objective of this study was to evaluate the role of cytochrome P450 monooxygenases (P450s) in Imisun resistance. The response to imazapyr herbicide in combination with P450s inhibitor malathion was evaluated in 2 Imisun lines, IMI-1 and RHA426. Malathion reduced herbicide efficacy in both lines, but IMI-1 was affected in a greater extent. A significant reduction in plant growth in response to P450s inhibitors 1-aminobenzotriazole and piperonyl butoxide treatment was detected in the Imisun line HA425. The increased susceptibility to imazapyr after P450s-inhibitor treatment indicates that herbicide metabolism by P450s is a mechanism involved in Imisun resistance. These results also suggest the involvement of different P450s isozymes in endowing resistance to imazapyr in Imisun cultivars.Fil: Breccia, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Gil, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Vega, Tatiana Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Altieri, Emiliano. Nidera S. A. Departamento de Biotecnología; ArgentinaFil: Bulos, Mariano. Nidera S. A. Departamento de Biotecnología; ArgentinaFil: Picardi, Liliana Amelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Nestares, Graciela María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentin

Occurrence of the rust resistance gene Lr37 from Aegilops ventricosa in Argentine cultivars of wheat

Leaf rust of wheat ( Triticum aestivum L.) caused by the fungus Puccinia triticina (formerly P. recondita f. sp. tritici), is one of the most important foliar diseases of this crop. Lr37 rust resistance gene, which confers resistance in wheat against leaf rust, was introgressed into cultivated wheat from Aegilops ventricosa Tausch. Rust races with virulence to Lr37 have been identified in different countries, but it still provides resistance to a wide range of races and is useful in combination with other resistance genes. There are no reports about the presence, frequency and origin of Lr37 in Argentinean wheat cultivars. In this work, we analyzed 88 registered Argentinean wheat cultivars developed by different breeding companies and institutions during the last 15 years by means of a molecular marker which is diagnostic of the 2NS-2AS translocation which carries Lr37. Only 4 cultivars showed the amplification product associated with this chromosome fragment. These four cultivars which carry the translocated 2NS-2AS chromosome were registered by the same breeding company during the last seven years and all of them have European germplasm in their genealogy. To the best of our knowledge this is the first report of the presence of Lr37 in registered South American cultivars

Effect of Ahasl1-1 and Ahasl1-4 alleles on herbicide resistance and its associated dominance in sunflower

BACKGROUND: Acetohydroxyacid synthase large subunit 1 (Ahasl1) is a multiallelic locus involved in herbicide resistance in sunflower. Ahasl1-1 and Ahasl1-4 alleles harbor different point mutations that lead to different amino acid substitutions (Ala205Val and Trp574Leu, respectively). The objectives of this work were to evaluate the effect of these alleles at the enzymatic and whole-plant levels, and to determine the dominance relationships for imazapyr and metsulfuron-methyl herbicides. RESULTS: Resistant near-isogenic lines showed significantly lower specific AHAS activity than susceptible near-isoline. However, kinetic studies indicated that mutations did not change AHAS pyruvate affinity. Dose–response for six near-isolines carrying different combinations of Ahasl1-1 and Ahasl1-4 alleles and two herbicides (imazapyr and metsulfuron-methyl) were evaluated at whole-plant and enzymatic levels. Ahasl1-1 allele conferred moderate resistance to imazapyr and low resistance to metsulfuron-methyl. Conversely, Ahasl1-4 allele endowed high levels of resistance for both herbicides. Dominance of resistance at whole-plant level showed a semi-dominant behavior among the alleles for both herbicides. CONCLUSION: Ahasl1-4 allele confers higher resistance levels than Ahasl1-1 when evaluated with imazapyr and metsulfuron-methyl. Dominance estimations suggested that both parental lines should carry a resistance trait when developing hybrids.Fil: Breccia, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Biología. Cátedra de Genética; ArgentinaFil: Gianotto, Laura Noelia. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Biología. Cátedra de Genética; ArgentinaFil: Altieri, Emiliano. Nidera S. A. Departamento de Biotecnología; ArgentinaFil: Bulos, Mariano. Nidera S. A. Departamento de Biotecnología; ArgentinaFil: Nestares, Graciela María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Departamento de Biología. Cátedra de Genética; Argentin

History of the race structure of Orobanche cumana and the breeding of sunflower for resistance to this parasitic weed: A review

<p class="Default">Broomrape, caused by <em>Orobanche cumana</em>, has affected sunflowers since the early 20^th century in Eastern Europe. Currently, it limits sunflower oil production in Southern and Eastern Europe and in some areas of Asia, causing around 50% seed losses when susceptible hybrids are grown. Covered in this review are aspects such as: biological processes that are common to <em>Orobanche</em> spp. and/or particular to <em>O. cumana</em> in sunflower, genetic resistance and its mechanisms, races of the parasite identified in different countries throughout the time and their increasing virulence, and breeding for resistance to some herbicides as a novel control option. The main purpose is to present an updated and, as far as possible, complete picture of the way both the parasitic weed and its host crop have evolved in time, and how they co-exist in the current agriculture. Additionally, we propose a system for determining the races of the parasite that can be internationally adopted from now. In the context of minimal harmful effects on the environment, changing patterns of land use in farming systems, and global environment changes, the final goal of this work is to provide all those interested in parasites from field crops and their integrated management compiled information on the sunflower – <em>O. cumana</em> system as a case study.</p

History of the race structure of Orobanche cumana and the breeding of sunflower for resistance to this parasitic weed: A review

Broomrape, caused by Orobanche cumana, has affected sunflowers since the early 20th century in Eastern Europe. Currently, it limits sunflower oil production in Southern and Eastern Europe and in some areas of Asia, causing around 50% seed losses when susceptible hybrids are grown. Covered in this review are aspects such as: biological processes that are common to Orobanche spp. and/or particular to O. cumana in sunflower, genetic resistance and its mechanisms, races of the parasite identified in different countries throughout the time and their increasing virulence, and breeding for resistance to some herbicides as a novel control option. The main purpose is to present an updated and, as far as possible, complete picture of the way both the parasitic weed and its host crop have evolved in time, and how they co-exist in the current agriculture. Additionally, we propose a system for determining the races of the parasite that can be internationally adopted from now. In the context of minimal harmful effects on the environment, changing patterns of land use in farming systems, and global environment changes, the final goal of this work is to provide all those interested in parasites from field crops and their integrated management compiled information on the sunflower – O. cumana system as a case study