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Passo Fundo, Brazil

Nunes Maciel J.L.,Embrapa Wheat
CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources

Blast disease is one of the major constraints for food production in the world, affecting many crops of agricultural importance. Wheat blast, since it was first report in the mid-1980s, has been responsible for considerable damage on the wheat fields in several South American countries such as Brazil, Bolivia and Paraguay. Rice blast disease has often been considered as a model for studies on plant-pathogen interactions. Loss of the avirulence gene AVR-0039 and mutations on the AVR-Pita are significant examples associated with this interaction. The first example is related to the adaptation of Magnaporthe oryzae to the rice crop and the second to the breakdown in cultivar resistance. A large number of genes (about 80 so far) with complete resistance to rice blast have been described, and 13 of them have been cloned. These results, involving avirulence and resistance genes, are important for understanding the biological mechanisms of interaction between pathogen and host, in considering finding strategies to control the disease. There is great concern about the potential spread of the wheat blast pathogen to locations where this disease does not currently occur. There are some wheat-producing regions in the world where wheat blast has not been reported so far, but which have climatic conditions very similar to the regions in South America where wheat blast attacks quite frequently. This situation, in a scenario of climate change, is concerning and demands research action. Source

Zhou G.,University of Tasmania | Zhou G.,CSIRO | Pereira J.F.,Embrapa Wheat | Delhaize E.,CSIRO | And 3 more authors.
Journal of Experimental Botany

Malate and citrate efflux from root apices is a mechanism of Al 3+ tolerance in many plant species. Citrate efflux is facilitated by members of the MATE (multidrug and toxic compound exudation) family localized to the plasma membrane of root cells. Barley (Hordeum vulgare) is among the most Al3+-sensitive cereal species but the small genotypic variation in tolerance that is present is correlated with citrate efflux via a MATE transporter named HvAACT1. This study used a biotechnological approach to increase the Al3+ tolerance of barley by transforming it with two MATE genes that encode citrate transporters: SbMATE is the major Al 3+-tolerance gene from sorghum whereas FRD3 is involved with Fe nutrition in Arabidopsis. Independent transgenic and null T3 lines were generated for both transgenes. Lines expressing SbMATE showed Al 3+-activated citrate efflux from root apices and greater tolerance to Al3+ toxicity than nulls in hydroponic and short-term soil trials. Transgenic lines expressing FRD3 exhibited similar phenotypes except citrate release from roots occurred constitutively. The Al3+ tolerance of these lines was compared with previously generated transgenic barley lines overexpressing the endogenous HvAACT1 gene and the TaALMT1 gene from wheat. Barley lines expressing TaALMT1 showed significantly greater Al3+ tolerance than all lines expressing MATE genes. This study highlights the relative efficacy of different organic anion transport proteins for increasing the Al3+ tolerance of an important crop species. © 2014 The Author. Source

Alves A.A.,Embrapa Agroenergy | Alves A.A.,Federal University of Vicosa | Rosado C.C.G.,Federal University of Vicosa | Faria D.A.,Embrapa Genetic Resources and Biotechnology | And 6 more authors.

Eucalypts are susceptible to a wide range of diseases. One of the most important diseases that affect Eucalyptus plantations worldwide is caused by the rust fungus Puccinia psidii. Here, we provide evidence on the complex genetic control of rust resistance in Eucalyptus inter-specific hybrids, by analyzing a number of full-sib families that display different patterns of segregation for rust resistance. These families are totally unrelated to those previously used in other inheritance studies of rust resistance. By using a full genome scan with 114 genetic markers (microsatellites and expressed sequence tag derived microsatellites) we also corroborated the existence and segregation of a resistance locus, explaining 11.5% of the phenotypic variation, on linkage group 3, corresponding to Ppr1. This find represents an additional validation of this locus in totally unrelated pedigree. We have also detected significant additive × additive digenic interactions with LOD >10.0 on several linkage groups. The additive and epistatic QTLs identified explain between 29.8 and 44.8% of the phenotypic variability for rust resistance. The recognition that both additive and non-additive genetic variation (epistasis) are important contributors to rust resistance in eucalypts reveals the complexity of this host-pathogen interaction and helps explain the success that breeding has achieved by selecting rust-resistant clones, where all the additive and non-additive effects are readily captured. The positioning of epistatic QTLs also provides starting points to look for the underlying genes or genomic regions controlling this phenotype on the upcoming E. grandis genome sequence. © 2011 Springer Science+Business Media B.V. Source

Galao O.F.,State University Londrina | Teixeira A.I.,Federal University of Vicosa | Moreira M.A.,Federal University of Vicosa | Carrao-Panizzi M.C.,Embrapa Wheat | Visentainer J.V.,State University of Maringa
Semina:Ciencias Agrarias

The objective of this study was to evaluate the effects of genetic and environmental variation on levels of beta-conglycinin and glycinin in commercial soybean cultivars, which were sown in showcases at Embrapa Soja, Londrina, simultaneously in Ponta Grossa, south Brazil. The concentration of protein fractions was determined by densitometry after electrophoresis in 20 cultivars, 14 conventional and 6 transgenic . We observed a significant variation as the ratio of beta-conglycinin (7S) and glycinin (11S) between the cultivars analyzed. Most 11S/7S ratios (2.21) was observed in the BRS 184, Ponta Grossa and lowest (1.31) in the BRS 233, Londrina. On average, transgenic varieties of Ponta Grossa were higher than in Londrina for both, taking into account the amount of protein fractions. Source

Panizzi A.R.,Embrapa Wheat | Agostinetto A.,University Of Passo Fundo | Lucini T.,Federal University of Parana | Pereira P.R.V.D.S.,Embrapa Wheat
Crop Protection

The green belly stink bug, Dichelops furcatus (F.) (Hemiptera: Heteroptera: Pentatomidae) is a pest of corn and soybean in southern Brazil. It also occurs on wheat, but information on its damage to this crop is limited. To determine the need for sustainable IPM programs, the impact of this bug on wheat production should be determined. Studies were conducted in the screenhouse with 1, 2 and 4 bugs caged for 16 days on single plants, cv. 'BRS Parrudo'. During the vegetative period (plants ca. 25 cm tall), all infestation levels significantly reduced plant height and ear head length, but did not reduce grain yield. Feeding damage caused tissue necrosis on leaves. During the booting stage, grain yield was significantly reduced with 2 and 4 bugs per plant; ear heads were small, discolored and abnormally developed. In 2013 and 2014 field trials, plants were infested for 18 days with 2, 4 and 8 bugs per m2 at vegetative, booting, and milky grain stage. At these infestation levels, there was no significant reduction in grain yield. There was a significant decrease in the number of normal seedlings resulting from seeds exposed to 8 bugs per m2 at the milky grain stage. Results suggest that, in general, there is no need to control D. furcatus on wheat, unless numbers are ≥8 bugs per m2 during reproductive period. © 2015 Elsevier Ltd. Source

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