ABSTRACT Searching for novel sources of resistance to head blast is essential to strengthen wheat production in the Cerrado´s biome. The objective of this work was to evaluate disease intensity measures and yield for 2NS and non-2NS carriers wheat genotypes with varying heading times in Minas Gerais, Brazil. A total of fourteen wheat genotypes, two susceptible and twelve resistant to head blast, were sown in 2014, 2015, and 2017 at the Sertãozinho Experimental Station of Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig) during three sowing dates without fungicide applications. The experimental design was a randomized complete block with three replicates. Blast incidence, severity, disease index and grain yield were influenced by the cycle of wheat genotypes and the sowing date, with the highest disease intensities and the lowest yields in the earliest sowing date. Blast incidence and disease index correlated negatively with grain yield and positively with percent yield losses. The group of wheat genotypes with higher grain yield (between 2,104.7 and 2,917.8 kg ha-1) and lower yield losses (between 44.3 and 54.8%) includes BR 18 as well as other five that do not carry the 2NS/2AS translocation: BRS Angico, PF 909, BRS 229, Embrapa 27, and CPAC 07340.

Abstract The objective of this work was to evaluate the effect of the presence of 2NVS translocation on the inheritance of wheat resistance to head blast, in F2 segregating lines from two biparental crosses. The IPF 86766 and 'Santa Fe' genotypes were used as female parents (both 2NVS carriers), and 'BRS 404', as the common male parent (non 2NVS carrier). Using a mixture of three isolates of Pyricularia oryzae Triticum, wheat spikes and rachises were evaluated for bleaching severity at five (%BS_5dpi) and seven days post-inoculation (%BS_7dpi), as well as for the number of infection points (IPR) and pathogen sporulation (SPO). Chi-square analyses showed that segregation follows a 3:1 Mendelian hypothesis, with a major locus with a dominant allele: %BS_7dpi for IPF 86766 × 'BRS 404' and IPR for 'Santa Fe' x 'BRS 404'. Therefore, this is the first known study to show that the 2NVS translocation responsible for resistance to head blast is a major locus with a dominant allele. In a controlled environment, 'BRS 404' shows bleaching severity and SPO similar with those occurring on IPF 86766 and 'Santa Fe'.

Resumo O objetivo deste trabalho foi avaliar o efeito da presença da translocação 2NVS sobre a herança da resistência de trigo à brusone, em linhagens segregantes F2 de dois cruzamentos biparentais. Os genótipos IPF 86766 e 'Santa Fe' foram usados como genitores femininos (ambos portadores d a 2NVS), e 'BRS 404', como genitor masculino comum (não por tador da 2NVS ). A partir da mistura de três isolados de Pyricularia oryzae Triticum, espigas e ráquis de trigo foram avaliadas quanto à severidade de branqueamento aos cinco (%BS_5dpi) e aos 7 dias após inoculação (%BS_7dpi), bem como quanto ao número de pontos de infecção (IPR) e à esporulação do patógeno (SPO). Análises de qui-quadrado mostraram que a segregação segue a hipótese mendeliana 3:1, com um loco de efeito maior, com alelo dominante: %BS_7dpi para IPF 86766 × 'BRS 404' e IPR para 'Santa Fe' × 'BRS 404'. Portanto, este é o primeiro estudo conhecido a mostrar que a translocação 2NVS responsável pela resistência à brusone de trigo é um loco principal com um alelo dominante. Em condições controladas de ambiente, 'BRS 404' apresenta severidade de branqueamento e SPO similares às que ocorrem em IPF 86766 e 'Santa Fe'.

Resumo Esta revisão apresenta o contexto atual da produção de trigo no Brasil, as estratégias de manejo para reduzir perdas de rendimento de grãos devido à brusone e as abordagens biotecnológicas para melhorar a resistência do trigo. A brusone do trigo é causada pelo fungo Magnaporthe oryzae patótipo Triticum (MoT) que pode infectar toda a parte aérea da planta. O principal sintoma da doença é o branqueamento das espigas que prejudica a produção de grãos, com perdas que podem chegar a 100% em cultivares suscetíveis. O primeiro relato mundial de brusone em espigas de trigo foi feito no Brasil, em 1985, e a doença atualmente é a principal restrição ao cultivo de trigo nas áreas tropicais e subtropicais dos biomas Cerrado e Mata Atlântica. Por muito tempo, o uso de fungicidas foi considerado ineficaz sob condições de alta pressão de doença. No entanto, trabalhos recentes apontam que a eficácia dos fungicidas depende da integração de outras medidas de controle, principalmente da escolha de cultivares com resistência moderada. Neste artigo de revisão, apresentam-se a alta variabilidade de reação do trigo ao MoT, bem como um painel de cultivares resistentes ou moderadamente resistentes (incluindo não portadoras da translocação 2NS), prontamente disponíveis para cultivo em regiões onde a brusone é endêmica.

Abstract This review paper presents the current context of wheat production in Brazil, the management strategies to reduce yield losses due to blast, and the biotechnological approaches to improve wheat resistance. Wheat blast or brusone is caused by the Magnaporthe oryzae Triticum (MoT) pathotype fungus that can infect all the aboveground parts of the plant. The main symptom of the blast disease is spike bleaching that impairs grain production, causing yield losses up to 100% in susceptible wheat cultivars. The first world report of blast in wheat spikes was in Brazil, in 1985, and, currently, the disease is the main constraint to wheat cultivation in tropical and subtropical areas of the Cerrado and Mata Atlântica biomes. For a long time, the use of fungicides has been found to be ineffective under high-pressure disease conditions. However, recent works have pointed out that fungicide efficiency depends on the integration of other control measures, particularly the choice of cultivars with moderate resistance. In this review paper, the high variability of wheat reaction to MoT is presented, as well as a panel of resistant or moderately resistant cultivars (including non-2NS carriers), promptly available for cultivation in regions where blast is endemic.

Resumo: O objetivo deste trabalho foi determinar as subunidades de gluteninas de alto peso molecular (HMW-GS) e a sua relação com os parâmetros de qualidade tecnológica em uma coleção de genótipos de trigo (Triticum aestivum). Foram avaliados 272 acessos em SDS-Page, e empregados marcadores moleculares para identificação do alelo 7oe e da translocação 1BL.1RS. Para 219 acessos com perfil de gluteninas homogêneo, foram identificados 53 perfis e 21 alelos. A combinação mais frequente foi 2*/7+9/5+10 (11,9%). A média de diversidade genética para os três locos Glu-1 avaliados foi de 0,67. Com base no perfil de HMW-GS e na presença da translocação 1BL.1RS, foi calculado o escore Glu-1 e analisada sua correlação com os parâmetros de qualidade tecnológica. Os efeitos principais dos locos Glu-1 e da translocação 1BL.1RS foram estimados. O escore Glu-1 mostrou correlação positiva significativa com volume de sedimentação, força de glúten, tenacidade da massa, extensibilidade da massa, índice de elasticidade, índice de dureza do grão e estabilidade, com valores entre 0,23 e 0,51. Os acessos com os alelos 1, 7oe+8 e 5+10 apresentaram os maiores valores para força de glúten e estabilidade. O escore dos alelos Glu-A1 deve ser ajustado para os genótipos e as condições de cultivo de trigo brasileiros.

Abstract: The objective of this work was to determine high-molecular-weight glutenin subunits (HMW-GS) and their relationship with technological quality parameters in a collection of wheat (Triticum aestivum) genotypes. Two hundred and seventy-two accessions were evaluated on SDS-Page, and molecular markers were used to identify the 7oe allele and 1BL.1RS translocation. For 219 accessions with a homogenous glutenin profile, 53 profiles and 21 alleles were identified. The most frequent combination was 2*/7+9/5+10 (11.9%). The mean value of genetic diversity for the three assessed Glu-1 loci was 0.67. Based on the HMW-GS profile and on the presence of the 1BL.1RS translocation, the Glu-1 score was calculated and its correlation with technological quality parameters was analyzed. The main effects of the Glu-1 loci and of the 1BL.1RS translocation were estimated. The Glu-1 score showed a significant positive correlation with sedimentation volume, gluten strength, dough tenacity, dough extensibility, elasticity index, grain hardness index, and farinograph stability, with values between 0.23 and 0.51. The accessions with the 1, 7oe+8, and 5+10 alleles showed the highest values for gluten strength and farinograph stability. The score of the Glu-A1 alleles should be adjusted to Brazilian wheat genotypes and cultivation conditions.

Resumo: O objetivo deste trabalho foi utilizar a análise de gluteninas, como um método simples e confiável, para identificar sementes F1 de trigo (Triticum aestivum) autofecundadas, para o desenvolvimento de populações de mapeamento via duplo-haploides (DH). Sementes F1 foram submetidas a análises de glutenina com eletroforese em gel, para verificação dos perfis heterozigóticos. As análises foram realizadas com a metade do endosperma de cada uma das 87 sementes F1. A outra metade do endosperma foi usada para desenvolver a população de mapeamento via DH. Plantas com padrões de banda diferentes dos esperados foram descartadas. Embora a incidência de sementes autofecundadas tenha sido relativamente baixa (apenas 8%), o rastreamento dos perfis heterozigóticos é extremamente importante, particularmente no desenvolvimento de populações de mapeamento confáveis.

Abstract: The objective of this work was to apply glutenin analysis, as a simple and reliable method, to identify self-pollinated wheat (Triticum aestivum) seeds in F1 crosses, when developing mapping populations using doubled-haploid (DH) technology. F1 seeds were subjected to glutenin analyses using gel electrophoresis, to verify and confirm their heterozygotic profiles. Glutenin analyses were carried out using one half of the endosperm of each of the 87 F1 seeds. The other half of the endosperm was used to develop the mapping population through DHs. Plants with band patterns different from the expected ones were discarded. Although the incidence of self-pollinated seeds was relatively low (only 8%), the screening of F1 heterozygotic profiles is extremely important, particularly when creating reliable mapping populations.

Abstract Drought limits wheat production in the Brazilian Cerrado biome. In order to search for candidate genes associated to the response to water deficit, we analyzed the gene expression profiles, under severe drought stress, in roots and leaves of the cultivar MGS1 Aliança, a well-adapted cultivar to the Cerrado. A set of 4,422 candidate genes was found in roots and leaves. The number of down-regulated transcripts in roots was higher than the up-regulated transcripts, while the opposite occurred in leaves. The number of common transcripts between the two tissues was 1,249, while 2,124 were specific to roots and 1,049 specific to leaves. Quantitative RT-PCR analysis revealed a 0.78 correlation with the expression data. The candidate genes were distributed across all chromosomes and component genomes, but a greater number was mapped on the B genome, particularly on chromosomes 3B, 5B and 2B. When considering both tissues, 116 different pathways were induced. One common pathway, among the top three activated pathways in both tissues, was starch and sucrose metabolism. These results pave the way for future marker development and selection of important genes and are useful for understanding the metabolic pathways involved in wheat drought response.

Resumo: O objetivo deste trabalho foi avaliar o efeito da época de semeadura sobre a intensidade da brusone, bem como as perdas na produtividade causada por essa doença em genótipos de trigo (Triticum aestivum). Os experimentos foram conduzidos, em 2013, na Fazenda Experimental de Sertãozinho da Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), em Patos de Minas, MG. Catorze genótipos de trigo e duas datas de semeadura foram avaliados. Utilizou-se o delineamento experimental de blocos ao acaso com três repetições. As variáveis avaliadas foram: incidência, severidade, peso de mil grãos (PMG), rendimento de grãos e perdas de produtividade. Calculou-se o índice da doença (ID), com base tanto na incidência quanto na severidade, para medir a intensidade da brusone em trigo. A data de semeadura afetou significativamente ID, PMG e rendimento de grãos. Houve forte correlação linear entre ID e danos (0,89), entre danos e PMG (-0,85) e entre danos e rendimento (-0,93). Para a brusone do trigo, IDs iguais ou maiores que 0,5 indicam potencial de danos de rendimento iguais ou superiores a 70%. A linhagem EP063030 e as cultivares MGS Brilhante e BRS 264 são as mais tolerantes à brusone quando expostas à alta intensidade da doença.

Abstract: The objective of this work was to assess the effect of sowing date on the intensity of wheat blast disease, as well as the yield losses caused by this disease in different wheat (Triticum aestivum) genotypes. The experiments were conducted in 2013 at the Sertãozinho experimental station of Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), in the municipality of Patos de Minas, in the state of Minas Gerais, Brazil. Fourteen wheat genotypes and two sowing dates were evaluated. The experimental design was a randomized complete block with three replicates. The evaluated variables were: incidence, severity, thousand grain weight (TGW), grain yield, and yield losses. A disease index (DI) was calculated, based both on the incidence and the severity of the disease, to measure blast intensity in wheat. The sowing date significantly affected DI, TGW, and grain yield. Significant linear correlations were observed between DI and yield losses (0.89), between losses and TGW (-0.85), and between losses and grain yield (-0.93). For wheat blast, DIs greater than or equal to 0.5 indicate potential yield losses equal to or greater than 70%. The EP063030 line and the MGS Brilhante and BRS 264 cultivars are the most tolerant to blast, when exposed to high disease pressure.

O objetivo deste trabalho foi avaliar um conjunto de marcadores microssatélites para identificação e caracterização varietal das cultivares de batata mais amplamente utilizadas no Brasil. O DNA das 14 variedades de batata foi genotipado com marcadores microssatélites, e os alelos foram visualizados em gel de poliacrilamida corado com prata. Vinte e quatro marcadores foram avaliados e apenas um loco foi monomórfico. Com base no padrão de bandas, foi obtido um conjunto com dois microssatélites capazes de identificar e diferenciar todas as cultivares analisadas.

The objective of this work was to evaluate a set of microsatellite markers for varietal identification and characterization of the most widespread potato cultivars in Brazil. The DNA from 14 potato cultivars was genotyped using microsatellite markers and the alleles were scored in silver-stained polyacrylamide gel. Twenty-four microsatellite markers were evaluated, and only one locus was monomorphic. Based on band patterns, a set of two microsatellites that were able to identify and differentiate all examined cultivars was obtained.