Marker-Assisted Recurrent Selection for Pyramiding Leaf Rust and Coffee Berry Disease Resistance Alleles in Coffea arabica L.

In this study, marker-assisted recurrent selection was evaluated for pyramiding resistance gene alleles against coffee leaf rust (CLR) and coffee berry diseases (CBD) in Coffea arabica. A total of 144 genotypes corresponding to 12 hybrid populations from crosses between eight parent plants with desired morphological and agronomic traits were evaluated. Molecular data were used for cross-certification, diversity study and resistance allele marker-assisted selection (MAS) against the causal agent of coffee leaf rust (Hemileia vastatrix) and coffee berry disease (Colletotrichum kahawae). In addition, nine morphological and agronomic traits were evaluated to determine the components of variance, select superior hybrids, and estimate genetic gain. From the genotypes evaluated, 134 were confirmed as hybrids. The genetic diversity between and within populations was 75.5% and 24.5%, respectively, and the cluster analysis revealed three primary groups. Pyramiding of CLR and CBD resistance genes was conducted in 11 genotypes using MAS. A selection intensity of 30% resulted in a gain of over 50% compared to the original population. Selected hybrids with increased gain also showed greater genetic divergence in addition to the pyramided resistance alleles. The strategies used were, therefore, efficient to select superior coffee hybrids for recurrent selection programs and could be used as a source of resistance in various crosses.

Zinc-dithiocarbimates for the control of Hemileia vastatrix: a versatile alternative.

BACKGROUND: The purpose of this work was to investigate the potential use of zinc-dithiocarbimate salts to control Hemileia vastatrix, the causal agent of the coffee leaf rust disease, and to evaluate their toxicity towards Apis mellifera, one of the most important coffee plant pollinators. RESULTS: Zinc-dithiocarbimate salts were prepared and fully characterized by infrared, proton (1 H) and carbon-13 (13 C) nuclear magnetic resonance and elemental analyses of carbon (C), hydrogen (H), nitrogen (N) and zinc (Zn). X-ray diffraction technique studies confirmed the proposed structures. The salts inhibited the germination of H. vastatrix spores in vitro, with a 50% inhibitory concentration (IC50 ) from 12 to 18 µmol.L-1 and a 90% inhibitory concentration (IC90 ) from 23 to 26 µmol.L-1 . Zinc-dithiocarbimate salts with the best in vitro results were selected for in vivo experiments with Coffea arabica var Caturra and with the pollinator A. mellifera. The results were similar to those of Mancozeb, a broad-spectrum contact fungicide, with a good control of the disease and low toxicity to the honeybee. CONCLUSION: The zinc-dithiocarbimate complex salts have potential to control coffee leaf rust, with low toxicity to the pollinator insect. © 2022 Society of Chemical Industry.

Designing the best breeding strategy for Coffea canephora: Genetic evaluation of pure and hybrid individuals aiming to select for productivity and disease resistance traits.

Breeding programs of the species Coffea canephora rely heavily on the significant genetic variability between and within its two varietal groups (conilon and robusta). The use of hybrid families and individuals has been less common. The objectives of this study were to evaluate parents and families from the populations of conilon, robusta, and its hybrids and to define the best breeding and selection strategies for productivity and disease resistance traits. As such, 71 conilon clones, 56 robusta clones, and 20 hybrid families were evaluated over several years for the following traits: vegetative vigor, incidence of rust and cercosporiosis, fruit ripening time, fruit size, plant height, canopy diameter, and yield per plant. Components of variance and genetic parameters were estimated via residual maximum likelihood (REML) and genotypic values were predicted via best linear unbiased prediction (BLUP). Genetic variability among parents (clones) and hybrid families was detected for most of the evaluated traits. The Mulamba-Rank index suggests potential gains up to 17% for the genotypic aggregate of traits in the hybrid population. An intrapopulation recurrent selection within the hybrid population would be the best breeding strategy because the genetic variability, narrow and broad senses heritabilities and selective accuracies for important traits were maximized in the crossed population. Besides, such strategy is simple, low cost and quicker than the concurrent reciprocal recurrent selection in the two parental populations, and this maximizes the genetic gain for unit of time.

The efficacy of washing strategies in the elimination of fungicide residues and the alterations on the quality of bell peppers.

Food safety problems caused by pesticide residues in vegetables have become a top issue to raise public concern. In this study, bell peppers were grown in an experimental field and sprayed with two systemic (azoxystrobin and difenoconazole) and one contact (chlorothalonil) fungicides. Ozone (ozonated water and water continuously bubble with ozone) or conventional domestic (washing with distilled water, detergent, acetic acid, sodium bicarbonate, and sodium hypochlorite solutions) procedures were investigated to identify the most effective way to remove fungicide residues in bell peppers. The residues in the fruits and the washing solutions were determined by solid-liquid extraction with a low-temperature partition (SLE/LTP) and liquid-liquid extraction with a low-temperature partition (LLE/LTP), respectively, and analyzed by gas chromatography. Water continuously bubbled with ozone a concentration of 3 mg L-1 was the most efficient treatment with removal of fungicides residues ranging from 67% to 87%. However, similar treatment at a lower concentration (1 mg L-1) did not only efficiently removed fungicide residues (between 53% and 75%) but also preserving the quality of the fruit along a storage time of 13 days. Among the conventional solutions, sodium bicarbonate at 5% showed good efficiency removing between 60% and 81% of the fungicide residues from bell peppers, affecting the color quality of the fruit. Overall, the most affected physicochemical parameters in bell peppers after the treatments were weight loss, color, and vitamin C content.

In silico guided structural and functional analysis of genes with potential involvement in resistance to coffee leaf rust: A functional marker based approach.

Physiology-based differentiation of SH genes and Hemileia vastatrix races is the principal method employed for the characterization of coffee leaf rust resistance. Based on the gene-for-gene theory, nine major rust resistance genes (SH1-9) have been proposed. However, these genes have not been characterized at the molecular level. Consequently, the lack of molecular data regarding rust resistance genes or candidates is a major bottleneck in coffee breeding. To address this issue, we screened a BAC library with resistance gene analogs (RGAs), identified RGAs, characterized and explored for any SH related candidate genes. Herein, we report the identification and characterization of a gene (gene 11), which shares conserved sequences with other SH genes and displays a characteristic polymorphic allele conferring different resistance phenotypes. Furthermore, comparative analysis of the two RGAs belonging to CC-NBS-LRR revealed more intense diversifying selection in tomato and grape genomes than in coffee. For the first time, the present study has unveiled novel insights into the molecular nature of the SH genes, thereby opening new avenues for coffee rust resistance molecular breeding. The characterized candidate RGA is of particular importance for further biological function analysis in coffee.

Correction to: High throughput transcriptome analysis of coffee reveals prehaustorial resistance in response to Hemileia vastatrix infection.

All the transcriptome sequencing data mentioned in the original article is publicly available at the National Center of Biotechnology Information (NCBI).

Genome sequencing and transcript analysis of Hemileia vastatrix reveal expression dynamics of candidate effectors dependent on host compatibility.

Coffee leaf rust caused by the fungus Hemileia vastatrix is one of the most important leaf diseases of coffee plantations worldwide. Current knowledge of the H. vastatrix genome is limited and only a small fraction of the total fungal secretome has been identified. In order to obtain a more comprehensive understanding of its secretome, we aimed to sequence and assemble the entire H. vastatrix genome using two next-generation sequencing platforms and a hybrid assembly strategy. This resulted in a 547 Mb genome of H. vastatrix race XXXIII (Hv33), with 13,364 predicted genes that encode 13,034 putative proteins with transcriptomic support. Based on this proteome, 615 proteins contain putative secretion peptides, and lack transmembrane domains. From this putative secretome, 111 proteins were identified as candidate effectors (EHv33) unique to H. vastatrix, and a subset consisting of 17 EHv33 genes was selected for a temporal gene expression analysis during infection. Five genes were significantly induced early during an incompatible interaction, indicating their potential role as pre-haustorial effectors possibly recognized by the resistant coffee genotype. Another nine genes were significantly induced after haustorium formation in the compatible interaction. Overall, we suggest that this fungus is able to selectively mount its survival strategy with effectors that depend on the host genotype involved in the infection process.

Early Selection Enabled by the Implementation of Genomic Selection in Coffea arabica Breeding.

Genomic Selection (GS) has allowed the maximization of genetic gains per unit time in several annual and perennial plant species. However, no GS studies have addressed Coffea arabica, the most economically important species of the genus Coffea. Therefore, this study aimed (i) to evaluate the applicability and accuracy of GS in the prediction of the genomic estimated breeding value (GEBV); (ii) to estimate the genetic parameters; and (iii) to evaluate the time reduction of the selection cycle by GS in Arabica coffee breeding. A total of 195 Arabica coffee individuals, belonging to 13 families in generation of F2, susceptible backcross and resistant backcross, were phenotyped for 18 agronomic traits, and genotyped with 21,211 SNP molecular markers. Phenotypic data, measured in 2014, 2015, and 2016, were analyzed by mixed models. GS analyses were performed by the G-BLUP method, using the RKHS (Reproducing Kernel Hilbert Spaces) procedure, with a Bayesian algorithm. Heritabilities and selective accuracies were estimated, revealing moderate to high magnitude for most of the traits evaluated. Results of GS analyses showed the possibility of reducing the cycle time by 50%, maximizing selection gains per unit time. The effect of marker density on GS analyses was evaluated. Genomic selection proved to be promising for C. arabica breeding. The agronomic traits presented high complexity for they are controlled by several QTL and showed low genomic heritabilities, evidencing the need to incorporate genomic selection methodologies to the breeding programs of this species.

High throughput transcriptome analysis of coffee reveals prehaustorial resistance in response to Hemileia vastatrix infection.

KEY MESSAGE: We provide a transcriptional profile of coffee rust interaction and identified putative up regulated resistant genes Coffee rust disease, caused by the fungus Hemileia vastatrix, is one of the major diseases in coffee throughout the world. The use of resistant cultivars is considered to be the most effective control strategy for this disease. To identify candidate genes related to different mechanism defense in coffee, we present a time-course comparative gene expression profile of Caturra (susceptible) and Híbrido de Timor (HdT, resistant) in response to H. vastatrix race XXXIII infection. The main objectives were to obtain a global overview of transcriptome in both interaction, compatible and incompatible, and, specially, analyze up-regulated HdT specific genes with inducible resistant and defense signaling pathways. Using both Coffea canephora as a reference genome and de novo assembly, we obtained 43,159 transcripts. At early infection events (12 and 24 h after infection), HdT responded to the attack of H. vastatrix with a larger number of up-regulated genes than Caturra, which was related to prehaustorial resistance. The genes found in HdT at early hours were involved in receptor-like kinases, response ion fluxes, production of reactive oxygen species, protein phosphorylation, ethylene biosynthesis and callose deposition. We selected 13 up-regulated HdT-exclusive genes to validate by real-time qPCR, which most of them confirmed their higher expression in HdT than in Caturra at early stage of infection. These genes have the potential to assist the development of new coffee rust control strategies. Collectively, our results provide understanding of expression profiles in coffee-H. vastatrix interaction over a time course in susceptible and resistant coffee plants.

Pesticide residue removal in classic domestic processing of tomato and its effects on product quality.

This study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, including acidity and chroma, and also caused weight loss. Acetic acid (0.15 and 5%) and hypochlorite (1%) solutions had the greatest effect on these parameters.

Identification of sources of resistance to anthracnose stalk rot in maize / Identificação de fontes de resistência à antracnose do colmo do milho

ABSTRACT: Adoption of resistant cultivars is the primary measure used to control anthracnose stalk rot. The goal of this study was to identify maize-resistant genotypes to anthracnose stalk rot, which are similar to the hybrid 2B710. Experiments were performed at Embrapa Maize and Sorghum experimental fields in Brazil. The first experimental trial evaluated 234 maize lines as well as two commercials hybrids, BRS1010 (susceptible) and 2B710 (resistant). Artificial inoculations were performed with a strain at the blister (R2) phase, and evaluation of disease severity was performed after 30 days. The second experimental trial evaluated 48 maize lines and hybrids, inoculated with two Colletotrichum graminicola strains. In the first trial, eight resistance groups were formed, and the last lines were more resistant, as was the hybrid 2B710, with values between 11.50% and 23.0% of severity. In the second trial, there was an interaction between the two factors, lines and isolates, and the lines often showed the same reaction features as those obtained in the first trial. However, the disease severity was higher for most lines, even when using other isolates. These lines with effective levels of resistance could be used in future studies of inheritance, in programs to develop hybrids, and to identify molecular markers associated with resistance to anthracnose stalk rot in maize.

RESUMO: O uso de cultivares resistentes é a principal medida para o manejo da antracnose do colmo em milho. Neste trabalho, objetivou-se identificar linhagens com níveis de resistência à antracnose do colmo, similar ao híbrido 2B710, considerado resistente. Dois experimentos foram conduzidos na Embrapa Milho e Sorgo. No primeiro experimento, foram avaliados 234 linhagens e os híbridos BRS1010 (suscetível) e 2B710 (resistente). Foi realizada inoculação artificial com um isolado de C. graminicola , na fase de pré-pendoamento e, após 30 dias, foi realizada a avaliação da severidade da antracnose no colmo. O segundo experimento foi conduzido com 48 linhagens e os híbridos inoculados com dois isolados de C. graminicola . No primeiro experimento, os genótipos formaram oito grupos com base na severidade da doença e as linhagens do último grupo foram consideradas as mais resistentes, incluindo o híbrido 2B710, em que os genótipos apresentaram valores de severidade entre 11,50 a 23%. No segundo experimento, houve interação entre os fatores linhagens e isolados e, de modo geral, as linhagens apresentaram a mesma tendência de reação obtida no primeiro experimento, no entanto, a severidade da doença foi maior para a maioria das linhagens, mesmo quando utilizado o outro isolado. Com isso, foi possível realizar a seleção de linhagens com bons níveis de resistência, as quais podem ser utilizadas em programas de melhoramento, em estudos de herança, desenvolvimento de híbridos e identificação de marcadores moleculares, associados com resistência à antracnose do colmo.

Determination of pesticides in lettuce using solid-liquid extraction with low temperature partitioning.

This work describes the optimization and validation of a method employing solid-liquid extraction with low temperature partitioning (SLE/LTP) together with analysis by gas chromatography with electron capture detection (GC/ECD) for the determination of nine pesticides (chlorothalonil, methyl parathion, procymidone, endosulfan, iprodione, λ-cyhalothrin, permethrin, cypermethrin, and deltamethrin) in lettuce. The method was found to be selective, accurate, and precise, with means recovery values in the range of 72.3-103.2%, coefficients of variation ⩽ 12%, and detection limits in the range 0.4-37 µg kg(-1). The matrix components significantly influence the chromatographic response of the analytes (above 10%). The optimized and validated method was applied to determine the residual concentrations of the fungicides iprodione and procymidone that had been applied to field crops of lettuce. The maximum residual concentrations of the pesticides in the lettuce samples were 13.6 ± 0.4 mg kg(-1) (iprodione) and 1.00 ± 0.01 mg kg(-1) (procymidone), on the day after application of the products.

In silico identification of coffee genome expressed sequences potentially associated with resistance to diseases.

Sequences potentially associated with coffee resistance to diseases were identified by in silico analyses using the database of the Brazilian Coffee Genome Project (BCGP). Keywords corresponding to plant resistance mechanisms to pathogens identified in the literature were used as baits for data mining. Expressed sequence tags (ESTs) related to each of these keywords were identified with tools available in the BCGP bioinformatics platform. A total of 11,300 ESTs were mined. These ESTs were clustered and formed 979 EST-contigs with similarities to chitinases, kinases, cytochrome P450 and nucleotide binding site-leucine rich repeat (NBS-LRR) proteins, as well as with proteins related to disease resistance, pathogenesis, hypersensitivity response (HR) and plant defense responses to diseases. The 140 EST-contigs identified through the keyword NBS-LRR were classified according to function. This classification allowed association of the predicted products of EST-contigs with biological processes, including host defense and apoptosis, and with molecular functions such as nucleotide binding and signal transducer activity. Fisher's exact test was used to examine the significance of differences in contig expression between libraries representing the responses to biotic stress challenges and other libraries from the BCGP. This analysis revealed seven contigs highly similar to catalase, chitinase, protein with a BURP domain and unknown proteins. The involvement of these coffee proteins in plant responses to disease is discussed.

Silicato de potássio, acibenzolar-S-metil e fungicidas no controle da ferrugem da soja / Potassium silicate, acibenzolar-S-methyl and fungicides on the control of soybean rust

A produção da soja pode ser afetada pela ocorrência de várias doenças. Dentre estas, a ferrugem, causada pelo fungo Phakopsora pachyrhizi, tem se destacado. Atualmente, novas estratégias de controle para essa doença devem ser pesquisadas. Assim, este trabalho teve como objetivo avaliar a eficiência do silicato de potássio (KSi), acibenzolar-S-metil e fungicidas no controle da ferrugem da soja. Um experimento foi conduzido em condições de campo, em delineamento em blocos ao acaso, utilizando-se 10 tratamentos, com três repetições. Foi utilizada a cultivar 'Monarca' por ser suscetível à ferrugem. Os tratamentos utilizados foram: T1 - testemunha (pulverização com água); T2 - KSi (1,2kg ha-1); T3 - KSi (2,4kg ha-1); T4 - KSi (3,6kg ha-1); T5 - KSi (4,8kg ha-1); T6 - tebuconazole (125g de i.a. ha-1); T7 - cloreto de potássio (61,72g L-1); T8 - mancozebe (2400g de i.a. ha-1); T9 - mancozebe (2400g de i.a. ha-1) + KSi (1,2kg ha-1) e T10 - acibenzolar-S-metil (125g de i.a. ha-1). As plantas da bordadura foram inoculadas com uma suspensão de 5x10(5) uredosporos mL-1 no estádio V4 para constituírem fonte de inóculo, para as parcelas centrais. As plantas foram pulverizadas com os produtos que constituíram os tratamentos T2, T3, T4, T5, T7, T8 e T9 nos estádios V5, R1, R4 e R5.4 e os tratamentos T6 e T10 nos estádios R1, R4 e R5.4. As plantas foram pulverizadas com atomizador costal manual de bico cônico empregando-se um volume de calda de 200L ha-1. Foram realizadas cinco avaliações da severidade da ferrugem nos terços inferior, médio e superior das plantas utilizando-se uma escala diagramática variando de 0,6 a 78,5 por cento, e os dados obtidos foram utilizados para calcular a área abaixo da curva do progresso da ferrugem (AACPF). Não houve efeito significativo das doses de KSi na AACPF e severidade máxima (Ymax) nos terços inferior, médio e superior das plantas, além da produtividade. Os tratamentos 8, 9 e 10 apresentaram eficiência intermediária ...

Soybean production can be affected by the occurrence of several diseases. Among them, the rust, caused by the fungus Phakopsora pachyrhizi, has been outstanding. Nowadays, new strategies to control soybean rust need to be searched. Therefore, this study aimed to evaluate the efficiency of potassium silicate (KSi), acibenzolar-S-methyl and some fungicides on the control of soybean rust. An experiment was carried out under field conditions in a randomized complete block design with 10 treatments and three replications. The cultivar 'Monarca' was used because it is susceptible to rust. The treatments used were: T1 - control (plants sprayed with water); T2 - KSi (1.2kg ha-1); T3 - KSi (2.4kg ha-1); T4 - KSi (3.6kg ha-1); T5 - KSi (4.8kg ha-1); T6 - tebuconazol (125g de a.i. ha-1); T7 - potassium cloride (61.72g L-1); T8 - mancozeb (2400g de a.i. ha-1); T9 - mancozeb (2400g de a.i. ha-1) + KSi (1.2kg ha-1) and T10 - acibenzolar-S-methyl (125g de a.i. ha-1). Plants from the two lateral lines were inoculated with a suspension of 5x10(5) uredospores/mL at the V4 growth stage to produce inoculum to infect plants at the two central lines. Plants were sprayed with the products that constituted the treatments T2, T3, T4, T5, T7, T8, and T9 at V5, R1, R4, and R5.4 growth stages; and the treatments T6 and T10 at R1, R4, and R5.4 growth stages. Plants were sprayed using a costal sprayer in a volume of 200L ha-1. A total of five disease severity evaluations at the low, medium and high part of the plant canopy were done using a diagrammatic scale ranging from 0.6 to 78.5 percent. Data were used to calculate the area under rust progress curve (AURPC). There was no effect of the KSi rates on AURPC and final disease severity (Ymax) at the low, medium and high part of the plant canopy. Yield was also unaffected. The treatments 8, 9, and 10 had an intermediary efficiency on rust control. The treatment 6 was the most efficient on rust control giving the lowest ...

Syntheses, crystal structure, spectroscopic characterization and antifungal activity of new N-R-sulfonyldithiocarbimate metal complexes.

Five new compounds with the general formula of (Bu(4)N)(2)[M(RSO(2)NCS(2))(2)], where Bu(4)N=tetrabutylammonium cation, (M=Ni, R=4-FC(6)H(4)) (1), (M=Zn, R=4-FC(6)H(4), 4-ClC(6)H(4), 4-BrC(6)H(4), 4-IC(6)H(4)), (2), (3), (4) and (5), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO(2)N=CS(2)K(2)) with nickel(II) chloride hexahydrate or zinc(II) acetate dihydrate in metanol:water 1:1. The elemental analyses and the IR data are consistent with the formation of the expected bis(dithiocarbimato)metal(II) complexes. The (1)H and (13)C NMR spectra showed the signals for the tetrabutylammonium cation and the dithiocarbimate moieties. The compounds 1, 2 and 5 were also characterized by X-ray diffraction techniques. The nickel(II) is coordinated by two N-4-fluorophenylsulphonyldithiocarbimato(2-) ligands forming a planar coordination. The zinc(II) exhibits distorted tetrahedral configuration in compounds 2 and 5 due to the chelation effect of two sulfur atoms of the N-R-sulfonyldithiocarbimate ligands. The antifungal activities of the compounds were tested in vitro against Colletotrichum gloeosporioides, an important fungus that causes the plant disease known as anthracnose in fruit trees. All the complexes were active.

Synthesis, characterization, absolute structural determination and antifungal activity of a new chlorinated aromatic avenaciolide analogue.

BACKGROUND: Avenaciolide, a natural product isolated from Aspergillus avenaceus H. Smith, possesses several interesting biological properties, such as antifungal and antibacterial activities and inhibition of glutamate transport in mitochondria. In a study aiming to discover new compounds with antifungal activity, a bis-gamma-lactone analogous to avenaciolide was prepared and characterized by elemental analysis, mass spectrometry, and infrared and NMR spectroscopy. RESULTS: The absolute structures of this compound and of the synthetic precursor (also a bis-gamma-lactone) were determined by X-ray diffraction analysis. The bis-gamma-lactones synthesized crystallize in the orthorhombic space group P2(1)2(1)2(1), and the crystal packings are supported by C--H...O hydrogen bonds. The compound showed antifungal activity against Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., while the synthetic precursor was inactive under the in vitro test conditions employed. CONCLUSION: The results indicate that it is not only the bis-gamma-lactone skeleton that is important to antifungal activity. The latter also depends on the presence of the exocyclic double bond possibly due to a Michael addition type reaction with the fungal enzymes.

Diferenças genéticas na eficiência de absorção, na translocação e na utilização de K, Ca e Mg em mudas enxertadas de cafeeiro / Genetics differences in the efficiency of absorption, translocation and use of K, Ca and Mg in grafted seedlings of coffee

O estudo da eficiência nutricional de plantas enxertadas de cafeeiro é importante para a seleção de combinações enxerto/porta-enxerto visando desenvolvimento e produção máximos. O presente trabalho teve como objetivo avaliar as diferenças genéticas na eficiência de absorção, no transporte e na utilização de Potássio, Cálcio e Magnésio em mudas enxertadas de cafeeiro. O plantio foi realizado em vasos de 20L contendo como substrato terra, areia e esterco na proporção de 3:1:1, em que as plantas permaneceram por 18 meses até a coleta do experimento. Utilizaram-se como enxertos quatro genótipos de Coffea. arabica L.: as variedades Catuaí Vermelho IAC 15 e Oeiras MG 6851 e os híbridos H419-10-3-4-4 e H514-5-5-3 do programa de melhoramento da EPAMIG/UFV. Como porta-enxerto, foram empregados cinco progênies famílias de meios-irmãos de clones de Coffea canephora Pierre cv. Conilon: "ES 21", "ES 36", "ES 26", "ES 23" e "ES 38" do programa de melhoramento de café robusta do INCAPER. Houve variação da eficiência nutricional de K, Ca e Mg das plantas de cafeeiro em função da combinação enxerto/porta-enxerto. Na maioria das vezes, as plantas enxertadas tiveram desempenho inferior ao do pé-franco quanto à eficiência de absorção, translocação e utilização do K, Ca e Mg, bem como na produção de matéria seca. As combinações da variedade Catuaí Vermelho IAC 15 com os porta-enxertos ES 26 e ES 23 foram eficientes quanto à utilização de Mg e à produção de matéria seca. A baixa eficiência de absorção de K e Mg das combinações de enxertia com a cultivar Oeiras MG 6851 podem ter contribuído para a redução de produção de matéria seca total das mesmas.

Studies on the nutritional efficiency of grafted coffee trees are important for the selection of the rootstocks/grafts combinations that aim at for a good development and maximum yield. This study aimed to evaluate the genetic differences in the efficiency of K, Ca and Mg uptake, transport and use in grafted coffee seedlings. Trees were planted in 20-L pots containing soil, sand and manure (3:1:1) to grow for 18 months, until harvest. As grafts, four genotypes of Coffea arabica L were used: varieties Catuaí Vermelho IAC 15 and Oeiras MG 6851 and hybrids H419-10-3-4-4 and H514-5-5-3, of the breeding program of EPAMIG/UFV. As rootstocks, five half-sib progenies of Coffea canephora Pierre cv. Conilon clones were used: 'ES 21', 'ES 36', 'ES 26', 'ES 23' and 'ES 38', of the robust coffee breeding program of INCAPER. The nutritional efficiency of the coffee trees regarding K, Ca and Mg varied with the graft/ rootstock combination. The performance of the grafted coffee plants was inferior to the control varieties, with regard to the nutritional efficiency and dry matter yield. Catuaí Vermelho IAC 15 combined with the rootstocks ES 26 and ES 23 was highly effective regarding Mg utilization and dry matter yield. The dry weight reduction in the cv. Oeiras MG 6851 combinations may be explained by the low potassium and magnesium uptake efficiency.

Synthesis and antifungal activity of aromatic bis-gamma-lactones analogous to avenaciolide.

Avenaciolide is a bis-gamma-lactone isolated from Aspergillus avenaceus and possesses antifungal activity. Here, we describe the total syntheses and characterization by elemental analyses, and IR and NMR spectroscopy of three new bis-gamma-lactones analogous to avenaciolide, where the octyl group of the natural product was replaced by aromatic groups. The effects of the avenaciolide, the novel compounds, and their synthetic precursors on the mycelia development and conidia germination of Colletotrichum gloeosporioides were evaluated in vitro. The new compounds were as active as avenaciolide in the tested conditions, while the synthetic precursors were inactive. The preparation and characterization of 15 new synthetic intermediates are also described.

Seletividade de defensivos agrícolas ao fungo entomopatogênico Beauveria bassiana / Selectivity of insecticides and fungicides to the entomopathogenic fungus Beauveria bassiana

A toxicidade relativa dos inseticidas organofosforados clorpirifós-metílico, dissulfotom, etiom, paratiom-metílico, do organoclorado endosulfam, da mistura do fungicida triadimenol e do inseticida dissulfotom e dos fungicidas inibidores da demetilação de esteróis triadimenol e tebuconazole ao fungo Beauveria bassiana (Balsamo) Vuillemin foi estudada em laboratório. As concentrações dos pesticidas que inibiram 99 por cento do crescimento micelial desse fungo, em miligramas de ingrediente ativo por ml foram: tebuconazole = 0,42; paration-metílico = 1,69; triadimenol = 6,53; triadimenol + dissulfotom = 14,42; clorpirifós-metílico = 31,75; etiom = 7.028,96; endosulfam = 10.326,76 e dissulfotom = 763.959,86. As equações de regressão da inibição do crescimento micelial ( por cento), em função da concentração obtida por ensaio in vitro em meio batata-destrose-ágar (BDA) impregnado com os ingredientes ativos desses compostos, foram usadas para se estimar a seletividade das concentrações prescritas para cafezais, pelos seus respectivos fabricantes. Tebuconazole, paratiom-metílico e clorpirifós-metílico foram altamente tóxicos ao fungo B. bassiana; endosulfam e triadimenol + dissulfotom apresentaram seletividade moderada e triadimenol, etiom e dissulfotom foram seletivos para esse fungo.

The relative toxicity of the insecticides organophosphates methyl-chlorpyrifos, disulfoton, ethion, methyl-parathion, the organochlorinate endosulfan and the mixture of the fungicide triadimenol and the insecticide disulfoton and the sterol demethylation inhibiter fungicide (triadimenol and tebuconazole) to the fungus Beauveria bassiana (Balsamo) Vuillemin was evaluated. Concentrations which inhibited radial mycelium growth (99 percent) of B. bassiana were 0.42; 1.69; 6.53; 14.42; 31.75; 7,028.96; 10,326.76 e 763,959.86 mg i.a/ml of tebuconazole, methyl-parathion, triadimenol, triadimenol + disulfoton, methyl-chlorpyrifos, ethion, endosulfan and disulfoton, respectively. The effects of these products were evaluated based on percentage of inhibition of radial mycelium growth of B. bassiana on potato dextrose-agar impregnated with them, after seven days. Tebuconazole, methyl-parathion and methyl-chlorpyrifos were highly toxic to B. bassiana; endosulfan and triadimenol + disulfoton were moderated toxic; while triadimenol, ethion, and disulfoton were selective to this fungi.