First report of maize rayado fino virus in corn fields in Santa Catarina, Brazil.

Maize (Zea mays L.) is the main cereal food of humans and animals in Brazil. In 2020 and 2021, a severe infestation of corn leafhoppers (Dalbulus maidis; Hemiptera: Cicadellidae) was observed in Santa Catarina State (South of Brazil). Subsequently, symptoms of chlorotic stripes limited in leaf veins started to appear in maize plants. Given the similarity of symptoms and the presence of high populations of corn leafhoppers in corn production areas, 30 plants in reproductive stage showing systemic symptoms were collected in summer and autumn from commercial fields of five municipalities in Santa Catarina: Campos Novos (27°23'18.0"S, 51°12'52.7"W), Lages (27°47'17.8"S, 50°18'16.9"W), Mafra (26°06'42"S, 49°48'25"W), Fraiburgo (27°01'36"S, 50°55'19"W), and Abelardo Luz (26°34'02"S, 52°20'02"W). The young leaves of these samples were used for molecular analyses targeting the maize rayado fino virus (MRFV; Tymoviridae: Marafivirus). Total nucleic acids were extracted using TRIzol® (Invitrogen, USA), following the manufacturer's instructions. These were used as a template for cDNA synthesis with the enzyme MMLV-RT (Promega, USA), following the manufacturer's instructions. The polymerase chain reaction (PCR) was performed using Gotaq® DNA polymerase (Promega, USA) and MRFV-09/MRFV-10 primers (Hammond et al. 1997). All PCR products were subjected to electrophoresis in 1% agarose gel and were visualized under ultraviolet light. Twenty-eight of the 30 tested plants were MRFV-positive, showing a fragment with an expected size of ~633 bp. To confirm our results, all MRFV-positive samples were sent for sequencing (GenBank accession numbers OM763708 - OM763710 and ON730784 - ON730806) and submitted to BLASTn search (https://blast.ncbi.nlm.nih.gov/Blast.cgi), resulting in identities ranging from 96.21% to 99.21% with the isolate "Brazil 26" of MRFV, which was detected in 2005 in São Paulo, Brazil (GenBank accession nº: AF186178) (Hammond and Bedendo 2005). A second set of primers was used to validate the first PCR, confirming MRFV infection (data not shown).Moreover, whitish streaks and leaf reddening were observed on the leaves of some plants; therefore, the identification for phytoplasmas (Candidatus Phytoplasma asteris) and spiroplasmas (Spiroplasma kunkelii) from the corn stunt complex was performed. For this, previously extracted nucleic acids from each sample were used as templates for a multiplex PCR using the primers CSSR6/CSSF2 and R16F2n/R16R2 (Gundersen and Lee 1996; Barros et al. 2001). Two plants were infected with only spiroplasma, 17 samples were infected with Spiroplasma and MRFV, and three samples were infected by these three pathogens. An increasing incidence of corn stunt has been observed in commercial fields in Santa Catarina in recent years. Mollicutes are commonly found and mostly studied as causal agents of corn stunt disease. On the contrary, despite being present in Brazil since the 1970s, the virus is less studied because its contribution to the corn stunt complex is still unknown (Hammond and Bedendo 2001). In this report, indications that the virus is expanding to different regions in southern Brazil were observed, which raises an opportunity for further evaluation and its consideration in monitoring programs. Moreover, to the best of our knowledge, this is the first report of MRFV in Santa Catarina, Brazil.

Warming and soil water availability affect plant-flower visitor interactions for Stylosanthes capitata, a tropical forage legume.

The reproductive success of a zoophilous plant species depends on biological interaction with pollinators, which involves both the provision and exploitation of flower resources. Currently, there is little information about how future climate change scenarios will impact interactions between plants and their flower visitors in the tropics. This study analyzes the effects of warming and two soil water conditions on interactions between the tropical forage legume species Stylosanthes capitata and its floral visitors during the flowering period. We used a temperature-free air-controlled enhancement (T-FACE) facility to simulate future warming scenarios by increasing canopy temperature. The tested treatments were: irrigated and ambient canopy temperature (Control); non-irrigated and ambient canopy temperature (wS); irrigated and elevated canopy temperature (eT, +2 °C above ambient canopy temperature); and non-irrigated and elevated canopy temperature (wSeT). The effects of treatments on the time of flower opening and closing, sugar concentration in the nectar, and plant-flower visitor interactions were assessed. In the warmed treatments, S. capitata flower opening occurred ~45 min earlier compared to non-warmed treatments, and flowers remained opened for only ~3 h. Further, the sugar concentration in the nectar from eT was 39% higher than in the Control. The effects of warming on floral biology and flower resource production in S. capitata had an impact on the plant-floral visitor relationships with the bees Apis mellifera and Paratrigona lineata, the most abundant potential pollinating floral visitors, and the butterfly visitor Hemiargus hanno. Additionally, around noon, the interactive and additive effects of the combined wS and eT treatments decreased insect visiting frequency. These results suggest that warming and soil water deficiency could affect flower-visitor interactions and thus the reproductive success of S. capitata in tropical belts.

Warming and elevated CO2 induces changes in the reproductive dynamics of a tropical plant species.

Tropical plant species are vulnerable to climate change and global warming. Since flowering is a critical factor for plant reproduction and seed-set, warming and elevated atmospheric carbon dioxide concentrations (eCO2) are crucial climate change factors that can affect plant reproductive dynamics and flowering related events in the tropics. Using a combined free-air CO2 enrichment and a free-air temperature-controlled enhancement system, we investigate how warming (+2 °C above ambient, eT) and elevated [CO2] (~600 ppm, eCO2) affect the phenological pattern, plant-insect interactions, and outcrossing rates in the tropical legume forage species Stylosanthes capitata Vogel (Fabaceae). In comparison to the control, a significantly greater number of flowers (NF) per plot (+62%) were observed in eT. Furthermore, in warmed plots flowers began opening approximately 1 h earlier (~09:05), with a canopy temperature of ~23 °C, than the control (~09:59) and eCO2 (~09:55) treatments. Flower closure occurred about 3 h later in eT (~11:57) and control (~13:13), with a canopy temperature of ~27 °C. These changes in flower phenology increased the availability of floral resources and attractiveness for pollinators such as Apis mellifera L. and visitors such as Paratrigona lineata L., with significant interactions between eT treatments and insect visitation per hour/day, especially between 09:00-10:40. In comparison to the control, the additive effects of combined eCO2 + eT enhanced the NF by 137%, while the number of A. mellifera floral visits per plot/week increased by 83% during the period of greatest flower production. Although we found no significant effect of treatments on mating system parameters, the overall mean multilocus outcrossing rate (tm = 0.53 ± 0.03) did confirm that S. capitata has a mixed mating system. The effects of elevated [CO2] and warming on plant-pollinator relationships observed here may have important implications for seed production of tropical forage species in future climate scenarios.

Association Mapping for Flowering Time and Moisture Loss of Grains in Maize Tropical Germplasm.

BACKGROUND AND OBJECTIVE: With the advent of high-scale genotyping platforms, association studies have become important tools for finding genomic regions of interest in breeding programs, due to the fact that their improved more accuracy than the other tools. The aim of this work was to map genomic regions associated with grain maturation in common maize strains. MATERIALS AND METHODS: For linkage disequilibrium mapping, 72 strains were previously genotyped for SNP markers on the 650K platform and their respective genotypic values were predicted for male and female flowering and area below the moisture curve. The analysis of association between the SNPs markers and the characters was performed using mixed linear model and stepwise multiple regression. RESULTS: The significant associations detected for male and female flowering were found to be distributed in all chromosomes, with a higher concentration in genomic regions of chromosomes 1, 2, 3, 5, 9 and 10. For the area below the moisture curve, it was found a smaller number of significant associations, being concentrated in the chromosomes 1, 2, 3, 6, 9 and 10 and absent in chromosomes 4 and 8. By stepwise analysis, it obtained complete models that account for 79, 93 and 56% of the variation for the genotypic values, respectively, with the identification of genomic regions pre-dominantly on chromosomes 1 and 3. CONCLUSION: Thus, the detection of similar and distinct genomic regions for these traits, reveals the potential for the use of significant associations detected in chromosomes 1 and 3 to obtain the germplasm maturity required in breeding programs.

CD 1252: health, quality and tolerance to pre-harvest sprouting / CD 1252: sanidade, qualidade e tolerancia a germinação

Resulting from the search for wheat cultivars with high yield potential, plant health, processing quality and tolerance to pre-harvest sprouting, CD 1252 was developed from the cross between cultivar IPR 85 and line OR1/3/BOW/GLENSON//BAGULA. Cultivar CD 1252 was tested in preliminary grain yield trials in 2005 and 2006, and then tested to determine the Value for Cultivation and Use (VCU) from 2007 to 2014, labelled CD 0711. All tests were arranged in an experimental design of randomized blocks, with three replications. The yield of cultivar CD 1252 was 5%, 4% and 1% higher than the average yield of the two best controls, respectively, in the wheat-growing regions VCU 2, 3 and 4. The wheat quality, potential for grain yield, and tolerance to pre-harvest sprouting of this cultivar are superior and it is tolerant to the main wheat diseases.

Buscando cultivares de potencial produtivo, sanidade, qualidade industrial e tolerância a germinação na espiga, foi desenvolvida a cultivar de trigo CD 1252, obtida do cruzamento entre a cultivar IPR 85 e a linhagem OR 1/3/BOW/GLENSON//BAGULA. A cultivar CD 1252, participou dos Ensaios Preliminares de rendimento de grãos em 2005 e 2006, sendo em seguida testada em Ensaios de Valor de Cultivo e Uso (VCU), nos anos de 2007 a 2014, com a sigla CD 0711. Todos os ensaios foram conduzidos em delineamento experimental de blocos ao acaso, com três repetições. A cultivar CD 1252 apresentou rendimento 5%, 4% e 1% superior à média das duas melhores testemunhas, respectivamente, nas Regiões Tritícolas de VCU 2, 3 e 4. A referida cultivar tem qualidade superior (trigo melhorador), alto potencial de rendimento de grãos, tolerância à germinação na espiga e tolerância às principais doenças.

A Genome-Wide Association Study for Agronomic Traits in Soybean Using SNP Markers and SNP-Based Haplotype Analysis.

Mapping quantitative trait loci through the use of linkage disequilibrium (LD) in populations of unrelated individuals provides a valuable approach for dissecting the genetic basis of complex traits in soybean (Glycine max). The haplotype-based genome-wide association study (GWAS) has now been proposed as a complementary approach to intensify benefits from LD, which enable to assess the genetic determinants of agronomic traits. In this study a GWAS was undertaken to identify genomic regions that control 100-seed weight (SW), plant height (PH) and seed yield (SY) in a soybean association mapping panel using single nucleotide polymorphism (SNP) markers and haplotype information. The soybean cultivars (N = 169) were field-evaluated across four locations of southern Brazil. The genome-wide haplotype association analysis (941 haplotypes) identified eleven, seventeen and fifty-nine SNP-based haplotypes significantly associated with SY, SW and PH, respectively. Although most marker-trait associations were environment and trait specific, stable haplotype associations were identified for SY and SW across environments (i.e., haplotypes Gm12_Hap12). The haplotype block 42 on Chr19 (Gm19_Hap42) was confirmed to be associated with PH in two environments. These findings enable us to refine the breeding strategy for tropical soybean, which confirm that haplotype-based GWAS can provide new insights on the genetic determinants that are not captured by the single-marker approach.

Genome-wide association mapping for flowering and maturity in tropical soybean: implications for breeding strategies.

Knowledge of the genetic architecture of flowering and maturity is needed to develop effective breeding strategies in tropical soybean. The aim of this study was to identify haplotypes across multiple environments that contribute to flowering time and maturity, with the purpose of selecting desired alleles, but maintaining a minimal impact on yield-related traits. For this purpose, a genome-wide association study (GWAS) was undertaken to identify genomic regions that control days to flowering (DTF) and maturity (DTM) using a soybean association mapping panel genotyped for single nucleotide polymorphism (SNP) markers. Complementarily, yield-related traits were also assessed to discuss the implications for breeding strategies. To detect either stable or specific associations, the soybean cultivars (N = 141) were field-evaluated across eight tropical environments of Brazil. Seventy-two and forty associations were significant at the genome-wide level relating respectively to DTM and DTF, in two or more environments. Haplotype-based GWAS identified three haplotypes (Gm12_Hap12; Gm19_Hap42 and Gm20_Hap32) significantly co-associated with DTF, DTM and yield-related traits in single and multiple environments. These results indicate that these genomic regions may contain genes that have pleiotropic effects on time to flowering, maturity and yield-related traits, which are tightly linked with multiple other genes with high rates of linkage disequilibrium.

Molecular marker linked to the rb1 gene and association with pre-harvest sprouting tolerance in wheat / Marcador molecular ligado ao gene rb1 em trigo e associação com a tolerância à germinação pré-colheita

The objective of this study was to identify microsatellites molecular markers linked to R genes, that confer the wheat grain color and evaluate the association with pre-harvest sprouting tolerance. This study was conducted with a F2 population with 203 plants, derived from the cross between PFAU x CD0666 genotypes, which segregates for one grain color gene. Were analyzed 43 molecular markers located in regions that containing R genes on 3B and 3D chromosomes. The Xbarc344 molecular marker was identified as linked to the R gene at a distance of 26.1 cM with 83.25% of selection efficiency. From the phenotypic analysis was confirmed the association between grain color with Xbarc344 molecular marker, however, there was no association between Xbarc344 with pre-harvest sprouting tolerance. Also, there was no association between grain color with pre-harvest sprouting tolerance. Although the grain color in wheat is a trait easy to select, it is known that not all R genes are involved with pre-harvest sprouting tolerance. Therefore, it is important the genetic mapping and specific evaluation of each R gene with pre-harvest sprouting tolerance. Thus, the molecular markers identified as associated with each R gene can be used to select plants that contain such genes, since it is not possible to identify phenotypically which R gene each plant has.

O objetivo deste trabalho foi identificar marcadores moleculares microssatélites ligados aos genes R, que conferem a cor do grão em trigo e avaliar a associação com a tolerância à germinação na espiga. O estudo foi realizado em uma população com 203 plantas F2, derivadas do cruzamento entre os genótipos PFAU x CD0666, que segregam para um gene da cor do grão. Foram analisados 43 marcadores moleculares localizados nas regiões que contêm os genes R nos cromossomos 3B e 3D. Foi identificado que o marcador Xbarc344 está ligado ao gene R a uma distância de 26,1 cM e apresentou eficiência de seleção de 83,25%. A partir da análise fenotípica foi possível confirmar a associação da cor do grão com o marcador Xbarc344, no entanto, não houve associação deste marcador e da cor do grão com a tolerância à germinação na espiga. Embora a cor do grão seja uma característica fácil de selecionar em trigo, é notório que nem todos os genes R estão envolvidos com a tolerância à germinação na espiga. Sendo assim, é importante o mapeamento genético e a avaliação específica da associação de cada gene R com esta característica. Assim, os marcadores moleculares identificados como associados a cada gene R podem ser utilizados para selecionar plantas que contenham tais genes, uma vez que não é possível identificar fenotipicamente qual gene R cada planta possuí.

CD 154: strong gluten wheat with high yield potential / CD 154: trigo melhorador e de alto potencial produtivo

Wheat breeding programs focus on potential grain yield, industrial quality, low plant height, and disease resistance. Cultivar CD 154 was a result of the search for cultivars with high yield potential and industrial wheat quality. This cultivar was derived from a cross between CD 104 and CDI 200104, by COODETEC, in 1999. Cultivar CD 154 was included in preliminary grain yield trials in 2005 and 2006, and was then tested to determine the Value of Cultivation and Use (VCU) from 2007 to 2012, with the acronym CD 0705. All trials were arranged in an experimental design of randomized blocks with three replications. The yield of cultivar CD 154 was 16 %, 10 % and 4 % higher than the mean yield of the two best controls, respectively, in the wheat-growing regions VCU 2, 3 and 4. The analysis of industrial quality, resulted in a mean gluten strength of 364 and mean stability of 17.1 min, which allows the inclusion cultivar CD 154 in the cultivar group of strong gluten wheat. The cultivar is classified as strong gluten wheat, has a high yield potential and good lodging resistance, and is therefore another promising alternative for wheat farmers of the hottest regions of Brazil.

Os programas de melhoramento de trigo estão direcionados para potencial de rendimento de grãos, qualidade industrial, baixa estatura de planta e resistência às doenças. Buscando cultivares de potencial produtivo e qualidade industrial foi desenvolvida a cultivar de trigo CD 154. Está cultivar, foi obtida do cruzamento entre as cultivares CD 104 e CDI 200104, pela COODETEC, em 1999. A cultivar CD 154, participou dos Ensaios Preliminares de rendimento de grãos em 2005 e 2006, sendo em seguida testada em Ensaios de Determinação de Valor e Uso (VCU), nos anos de 2007 a 2012, com a sigla CD 0705. Todos os ensaios foram conduzidos em delineamento experimental de blocos ao acaso, com três repetições. A cultivar CD 154 apresentou um rendimento 16%, 10% e 4% superior à média das duas melhores testemunhas, respectivamente, nas Regiões Tritícolas de VCU 2, 3 e 4. Os resultados de análise de qualidade industrial geraram uma média 364 de força geral de glúten e uma estabilidade média de 17,1 minutos, o que permite incluir a cultivar CD 154 no grupo de cultivares de trigo melhorador. A referida cultivar possui qualidade trigo melhorador, alto potencial de rendimento de grãos, boa resistência ao acamamento, sendo assim mais uma opção importante aos triticultores das Regiões mais quentes do Brasil.

Regeneração de plantas a partir de dois tipos de explantes de milho submetidos à transformação genética por biobalística / Regeneration of plants from two types of maize explants submitted to transformation by biolistic

O uso da biobalística na transformação genética de plantas requer a otimização de diversos parâmetros, entre eles, o desenvolvimento de protocolos para regeneração de plantas a partir de células transformadas. Este trabalho teve como objetivo avaliar a eficiência de regeneração de plantas de milho a partir de calos embriogênicos e de explantes sementes divididas, submetidos à transformação por biobalística, utilizando o gene bar como marcador de seleção. Foram submetidos 2000 agrupamentos de calos embriogênicos de milho e 2000 explantes sementes divididas à transformação por biobalística. A seleção dos eventos de transformação foi realizada em meios de cultivo suplementados com glifosinato de amônio. As plântulas selecionadas foram aclimatadas e transplantadas para vasos em casa de vegetação. Com a utilização de embriogênese somática, a eficiência de regeneração foi de 0,2%, enquanto que, com a utilização de sementes divididas, a eficiência de regeneração foi de 1,3%. Embora ambos os protocolos possibilitem a regeneração de plantas de milho submetidas à transformação por biobalística, há a necessidade de aumentar sua eficiência.

The use of biolistic on genetic transformation of plants requires an optimization of several parameters, including the protocol development for plant regeneration from transformed cells. The objective of this research was to evaluate the regeneration efficiency of maize plants from embryogenic callus and explants from split seeds submitted to transformation by biolistic using the gene bar as a selectable marker. It was submitted 2000 clusters of embryogenic callus and 2000 divided maize seeds to transformation by biolistic. The selection of transformation events was in culture medium supplemented with ammonium glifosinate. Selected seedlings were acclimatized and transplanted to pots in a greenhouse. Using somatic embryogenesis, the regeneration efficiency was 0.2%, while using split seeds explants the regeneration efficiency was 1.3%. Although both protocols allow the maize plant regeneration after transformation by biolistic, there is a need to increase its efficiency.

CD 151: cultivar de trigo de ampla adaptação / CD 151: wheat cultivar for wide adaptation

Potencial produtivo e qualidade industrial são objetivos dos programas de melhoramento de trigo, neste sentido foi desenvolvida a cultivar CD 151. Esta cultivar foi obtida do cruzamento entre as cultivares BRS 120 e ORL 95282, pela COODETEC, em 1999. A cultivar CD 151, participou dos Ensaios Preliminares de rendimento de grãos em 2006 e 2007, sendo em seguida testada em Ensaios de Determinação de Valor e Uso (VCU), nos anos de 2008, 2009 e 2010, com a sigla CD 0818. Todos os ensaios foram conduzidos em delineamento experimental de blocos ao acaso, com três repetições. A cultivar CD 151, apresentou um rendimento 12%, 7% e 9% superior à média das duas melhores testemunhas, respectivamente, nas Regiões Tritícolas de VCU 2, 3 e 4. A referida cultivar possui qualidade trigo melhorador, alto potencial de rendimento de grãos, boa resistência à ferrugem da folha, oídio, brusone e acamamento, sendo assim mais uma opção importante aos triticultores do Brasil.

Grain yield potential and industrial quality are objectives of breeding programs, in this sense was developed the wheat cultivar CD 151. This cultivar was obtained from the cross between the cultivars BRS 120 and ORL 95282, by COODETEC in 1999. Cultivar CD 151, participated in the Preliminary Tests of grain yield in 2006 and 2007, and after that in trials for Determination of Value and Use (VCU) in the years 2008, 2009 and 2010, with the acronym CD 0818. All tests were conducted in randomized blocks, with three replications. The CD 151 cultivar showed a grain yield 12%, 7% and 9% higher than the average of the best two check cultivars, respectively, in wheat growing regions of VCU 2, 3 and 4. This cultivar has strong gluten wheat, high yield potential, and good resistance to leaf rust, powdery mildew, rice blast and lodging, resulting so in another important option for wheat growers in Brazil.

Transcriptomics and systems biology analysis in identification of specific pathways involved in cacao resistance and susceptibility to witches' broom disease.

This study reports on expression analysis associated with molecular systems biology of cacao-Moniliophthora perniciosa interaction. Gene expression data were obtained for two cacao genotypes (TSH1188, resistant; Catongo, susceptible) challenged or not with the fungus M. perniciosa and collected at three time points through disease. Using expression analysis, we identified 154 and 227 genes that are differentially expressed in TSH1188 and Catongo, respectively. The expression of some of these genes was confirmed by RT-qPCR. Physical protein-protein interaction (PPPI) networks of Arabidopsis thaliana orthologous proteins corresponding to resistant and susceptible interactions were obtained followed by cluster and gene ontology analyses. The integrated analysis of gene expression and systems biology allowed designing a general scheme of major mechanisms associated with witches' broom disease resistance/susceptibility. In this sense, the TSH1188 cultivar shows strong production of ROS and elicitors at the beginning of the interaction with M. perniciosa followed by resistance signal propagation and ROS detoxification. On the other hand, the Catongo genotype displays defense mechanisms that include the synthesis of some defense molecules but without success in regards to elimination of the fungus. This phase is followed by the activation of protein metabolism which is achieved with the production of proteasome associated with autophagy as a precursor mechanism of PCD. This work also identifies candidate genes for further functional studies and for genetic mapping and marker assisted selection.

Análise dialélica e uso de marcadores microssatélites na avaliação de cultivares de trigo / Diallel analysis and use of microsatellite markers for the evaluation of wheat cultivars

Foi avaliada a capacidade combinatória de oito cultivares de trigo, por meio de um esquema dialélico analisado segundo o modelo quatro da metodologia de Griffing. Paralelamente, foi realizada uma análise de dissimilaridade com marcadores SSR, a partir de estimativas de distância genética baseadas em pedigree. Oito características foram avaliadas num experimento delineado em blocos ao acaso, com duas repetições. O agrupamento das cultivares a partir das distâncias genéticas foi efetuado com os métodos UPGMA e Tocher. Ficou evidenciada a variabilidade entre os genótipos de trigo. As cultivares 'CD 108', 'CD 0542' e 'CD 104' apresentaram grande capacidade geral de combinação para vários caracteres. Os maiores valores de capacidade específica de combinação foram detectados nos híbridos mais heterozigotos, formados pelo cruzamento de parentais integrantes de grupos diferentes. Os agrupamentos indicados pelo pedigree não coincidiram com os indicados a partir dos marcadores moleculares. As distâncias dos marcadores SSR provavelmente refletem melhor as relações entre as cultivares de trigo do que as distâncias medidas com base na genealogia. A falta de associação entre os padrões de agrupamento foi provavelmente devida às propriedades intrínsecas de cada forma de estimação das distâncias genéticas, as quais podem modificar a interpretação e a distribuição da variabilidade genética entre os genótipos avaliados.

The combining ability of eight wheat varieties was evaluated according to the fourth model of the Griffing's diallelic methodology. Studies on genetic dissimilarity based on microsatellite markers and genetic distance among genotypes from pedigree data were also performed. The experiment was carried out in a randomized block design with two replications. Eight traits were evaluated in the diallel. Genotypes were grouped according to the UPGMA and Tocher methods. Genetic variability among genotypes was evident. Varieties 'CD 108', 'CD 0542' and 'CD 104' were those who showed high values for general combining ability in several traits. Since the effects of specific combining ability were more important in those particularly heterozygous combinations obtained from varieties allocated in different clusters, field and molecular results coincided in a certain way. There was no a good coincidence between the dendrogram based on parentage coefficient and the one based on microssatellite markers. The very small association between standards of grouping was probably related to the intrinsic properties of each way of estimating the genetic distance, which can modify the interpretation and the distribution of the genetic variability in the evaluated genotypes.

Efeito de anos e épocas de semeadura sobre o desempenho agronômico e rendimento de cultivares de trigo em Palotina, PR / Effect of sowing dates and years on agronomic performance and yield of wheat cultivars in Palotina, state of Parana, Brazil

O objetivo do trabalho foi avaliar o desempenho agronômico e rendimento de grãos de cultivares de trigo em função de anos e épocas de semeadura. Os experimentos de campo foram instalados na Fazenda Experimental da Cooperativa Central de Pesquisa Agrícola (Coodetec), em Palotina, Estado do PR, Brasil, durante os anos agrícolas de 2006 e 2007. O delineamento utilizado foi em blocos completos com os tratamentos ao acaso, com quatro repetições. Foram avaliadas seis cultivares de trigo (CD 104, CD 105, CD 108, CD 110, CD 111 e CD 114), e cinco épocas de semeadura (22/03, 07/04, 20/04, 04/05 e 18/05). Realizou-se a análise estatística conjunta para anos, cultivares e épocas de semeadura, em todas as combinações. As características avaliadas foram: ciclo até o espigamento e até a maturação, e rendimento de grãos. A maturação foi a característica mais afetada durante os dois anos avaliados. De maneira geral, em ambos os anos, o maior rendimento de grãos, para as seis cultivares de trigo, foi obtido em semeaduras realizadas no mês de abril.

The objective of this work was to evaluate the agronomic performance and yield of wheat cultivars in response to different sowing dates and years. Field experiments were carried out on the Experimental Farm of the Central Cooperative Unit in Agricultural Research (Coodetec) in Palotina, state of Paraná, Brazil, during the agricultural years of 2006 and 2007. There was used the randomized block design with four replications. There were evaluated six wheat cultivars (CD 104, CD 105, CD 108, CD 110, CD 111 and CD 114), and five sowing dates (03/22, 04/07, 04/20, 05/04 and 05/18). The statistical analysis was carried out jointly for the years, cultivars, and sowing dates, in all combinations. Days until both emergency to flowering and emergency to maturation, and yield grain, were evaluated. Maturation was the characteristic more affected during the two years of study. In general, for both years, the highest grain yield, for the six wheat cultivars, was obtained in April sowing dates.

Tolerância à germinação na espiga em cultivares de trigo colhido na maturação fisiológica / Sprouting tolerance on spikes in wheat cultivars harvested in the physiological ripening

O objetivo deste trabalho foi identificar as diferenças de tolerância à germinação na pré-colheita em espigas de cultivares de trigo, submetidas a um sistema de chuva artificial. Foram realizados experimentos em duas localidades do Paraná (Palotina e Cascavel) com 12 cultivares. Quando as cultivares atingiram a maturidade fisiológica, as espigas foram colhidas e secadas em temperatura ambiente por um período de 20 dias. Foram analisadas 10 espigas por cultivar e submetidas a um sistema de chuva artificial. Após o período de molhamento, foram realizadas leituras pela escala de notas de 1 a 11. As espigas foram então debulhadas e submetidas à contagem de grãos germinados e não germinados. Esses resultados possibilitaram identificar as cultivares 'Frontana', 'IAPAR 53', 'ONIX', 'CD 108' e 'IPR 85' como as de maior nível de tolerância. Considerando todas as características avaliadas, 'Frontana' foi a cultivar com maior potencial de utilização no melhoramento genético. O emprego de notas visuais de germinação na espiga foi vantajoso porque permitiu a realização de avaliações rápidas e precisas em um grande número de cultivares, sem comprometer os resultados de seleção dos genótipos tolerantes.

The objective of the study was to identify the differences in pre-harvest sprouting tolerance in wheat spikes cultivars analyzed in artificial rain. Experiments were carried out in two locations of Paraná, Brazil (Palotina and Cascavel) with 12 cultivars. Spikes from plants in physiological maturation were harvested and dried at room temperature for 20 days. Ten spikes per cultivar were used and subjected to artificial rain. After the wetness duration were recorded notes from scale 1 to 11. In the next step, spikes were threshed and subjected to counting of sprouted and nonsprouted seeds. This results made possible to identify 'Frontana', 'IAPAR 53', 'ONIX', 'CD 108' and 'IPR 85' as the cultivars with the best level of tolerance. In general, Frontana was the most promising cultivar to be used in breeding programs. The use of visual grades as criteria of sprouting in the ears permitted a prompt and accurate evaluation of great number of cultivars without affecting the results of tolerant genotypes selection.

Desempenho agronômico de três cultivares de soja em diferentes épocas de semeadura em duas safras / Agronomic performance of three soybean cultivars at different sowing times in two agriculture years

O cultivo da soja, com cultivares precoces, em semeadura antecipada, é uma prática comum no oeste do Estado do Paraná, visando à safrinha do milho, no entanto, pouca pesquisa é relatada sobre esse fato. Portanto, neste trabalho,objetivou-se avaliar a influência da antecipação da semeadura da soja, no desempenho agronômico de três cultivares precoces de soja, semeadas em diferentes épocas, em dois anos agrícolas. Para tanto, foram instalados ensaios de competição na unidade da COODETEC, em Palotina - Paraná. O delineamento utilizado foi o em blocos casualizados, com quatro repetições, conduzido em dois anos agrícolas (2003/2004 e 2004/2005), com três cultivares precoces de soja (CD 202, CD 215 e CD 216), semeadas em cinco épocas (15/09, 30/09, 15/10, 30/10 e 15/11). As variáveis avaliadas foram: altura de inserção de primeira vagem, altura de planta, número de vagens e produtividade. Os dados coletados foram submetidos à análise de variância conjunta e realizados os desdobramentos das interações, quando necessário. Constatou-se que: a época preferencial de semeadura foi desfavorável à produção de grãos, especialmente no segundo ano agrícola; a maior produtividade de sementes para as três cultivares de soja foi obtida na semeadura realizada no mês de outubro; a antecipação na semeadura pode ser uma alternativa viável para a região oeste do Estado do Paraná.

Growing soybean by using early maturing soybean cultivars in anticipated sowing has been a common practice in the west of Paraná State aiming at the safrinha corn (fall cropping), however, there has not been enough research reported about this fact. Therefore, the objective of this study was to evaluate the influence of sowing anticipation of three early maturing soybean cultivars during two agriculture years. For this purpose, competition experiments were installed at COODETEC, in Palotina, Paraná State. A randomized complete block design with four replications was carried out within two agriculture years (2003/2004 and 2004/2005) by using three early maturing soybean cultivars (CD 202, CD 215, and CD 216) sowed on five different days (09/15, 09/30, 10/15, 10/30, and 11/15). Data were collected and submitted to variance analysis and the interaction design was accomplished whenever necessary. It was verified that the preferable period for sowing was unfavorable to the seed production, especially in the second agriculture year. The highest seed yield for the three soybean cultivars was obtained from the sowing accomplished in October. Potentially, sowing anticipation might be a viable alternative to the west region of Paraná State.

Genetic variability in Brazilian wheat cultivars assessed by microsatellite markers.

Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs.

Genetic variability in Brazilian wheat cultivars assessed by microsatellite markers

Wheat (Triticum aestivum) is one of the most important food staples in the south of Brazil. Understanding genetic variability among the assortment of Brazilian wheat is important for breeding. The aim of this work was to molecularly characterize the thirty-six wheat cultivars recommended for various regions of Brazil, and to assess mutual genetic distances, through the use of microsatellite markers. Twenty three polymorphic microsatellite markers (PMM) delineated all 36 of the samples, revealing a total of 74 simple sequence repeat (SSR) alleles, i.e. an average of 3.2 alleles per locus. Polymorphic information content (PIC value) calculated to assess the informativeness of each marker ranged from 0.20 to 0.79, with a mean of 0.49. Genetic distances among the 36 cultivars ranged from 0.10 (between cultivars Ocepar 18 and BRS 207) to 0.88 (between cultivars CD 101 and Fudancep 46), the mean distance being 0.48. Twelve groups were obtained by using the unweighted pair-group method with arithmetic means analysis (UPGMA), and thirteen through the Tocher method. Both methods produced similar clusters, with one to thirteen cultivars per group. The results indicate that these tools may be used to protect intellectual property and for breeding and selection programs.

Evolutionary history of Phakopsora pachyrhizi (the Asian soybean rust) in Brazil based on nucleotide sequences of the internal transcribed spacer region of the nuclear ribosomal DNA

Phakopsora pachyrhizi has dispersed globally and brought severe economic losses to soybean growers. The fungus has been established in Brazil since 2002 and is found nationwide. To gather information on the temporal and spatial patterns of genetic variation in P. pachyrhizi, we sequenced the nuclear internal transcribed spacer regions (ITS1 and ITS2). Total genomic DNA was extracted using either lyophilized urediniospores or lesions removed from infected leaves sampled from 26 soybean fields in Brazil and one field in South Africa. Cloning prior to sequencing was necessary because direct sequencing of PCR amplicons gave partially unreadable electrophoretograms with peak displacements suggestive of multiple sequences with length polymorphism. Sequences were determined from four clones per field. ITS sequences from African or Asian isolates available from the GenBank were included in the analyses. Independent sequence alignments of the ITS1 and ITS2 datasets identified 27 and 19 ribotypes, respectively. Molecular phylogeographic analyses revealed that ribotypes of widespread distribution in Brazil displayed characteristics of ancestrality and were shared with Africa and Asia, while ribotypes of rare occurrence in Brazil were indigenous. The results suggest P. pachyrhizi found in Brazil as originating from multiple, independent long-distance dispersal events.

Embriogênese somática a partir de embriões imaturos em genótipos de milho / Somatic embryogenesis from immature embryos in maize genotypes

A primeira etapa de um programa de transformação genética de plantas é o estabelecimento de um protocolo de regeneração de plantas, a partir de cultura de tecidos. A regeneração de plantas pode ser conseguida por meio de organogênese ou embriogênese. A embriogênese somática é dependente do genótipo das plantas utilizadas e a identificação de genótipos mais responsivos a este método de regeneração resulta em maior eficiência da técnica. O trabalho teve como objetivo identificar genótipos de milho com maior capacidade de produção de embriões somáticos e regeneração de plantas. Foram investigados 11 genótipos (linhagens e híbridos). As culturas foram obtidas a partir de embriões imaturos, inoculados em meio N6, suplementado com 690mg L-1 de prolina e 10mM de 2,4-D, com subcultivos quinzenais. Nos genótipos LD82025, CD308 e CML314, foram observados calos do tipo II, friáveis e embriogênicos. Esses genótipos foram submetidos ao processo de regeneração, destacando-se a linhagem LD82025. Os genótipos CD307, CD304, OC-705, 105-B e o GU04328 não apresentaram indução de calos embriogênicos. Os resultados indicam que a linhagem LD82025 é a mais promissora para utilização em um programa de transformação genética de plantas.

The establishment of a protocol for regenerating plants by tissue culture is the first step in breeding programs which have the objective of using genetic transformation on plants. The plant regeneration can be achieved either by organogenesis or embryogenesis. In the second case, the somatic embryogenesis depends on the identification of responsive genotypes which enhance the efficiency of the program. The aim of the present study was to identify maize genotypes with high capacity to produce somatic embryos and consequently regenerate maize plants. Eleven genotypes (inbreds and hybrids) were investigated in the present experiment. Under two-week periods, the cultures were obtained from immature embryos which were inoculated into growing medium N6 with 690mg L-1 of proline and 10mM of 2,4-D. Callis of type II, friable and embryogenic, were observed in the LD82025, CD308, and CML314 genotypes. After, they were submitted to the regeneration process and the best performance was achieved by the LD82025. No embryogenic callus was developed from CD307, CD304, OC-705, 105-B, and GU04328. In the present case, the inbred LD82025 is the most promising maize genotype for participating in a breeding program that will use the genetic transformation of maize plants.