Screening coffee genotypes for Cercospora coffeicola resistance in Brazil

Several efforts have been made by many researchers worldwide to develop coffee plants resistant to different Cercospora species; however, studies concerning C. coffeicola , specifically, are still incipient. In the present study, a blend of strains from this pathogen was inoculated into 18 Brazilian commercial cultivars, a coffee clone of Arabica, as well as into 41 accessions from the Germplasm Collection of Minas Gerais, to evaluate the genetic resistance ability within the population and select superior genotypes for the breeding program. After predicting genotypic values of the evaluated material, the most efficient way to select genotypes based on the data of severity to brown eye spot (BES) was also examined. Moreover, the action of defense mechanisms against C. coffeicola attacks was investigated by assessing the levels of total soluble phenolic compounds and soluble lignin in contrasting genotypes regarding disease susceptibility. Based on the results, the accession MG 1207 Sumatra demonstrated an intrinsic genetic capacity to maintain low levels of severity to brown eye spot. This genotype can thus substantially contribute to the development of new cultivars, which may lead to reduced use of pesticides. This study also evidenced that four evaluations of severity is enough to reach accuracy and efficiency for the severity of BES, thus providing expressive genetic gains. Finally, it is suggested that the levels of lignin and phenolic compounds are not associated with the resistance of coffee genotypes to brown eye spot.

Condições climáticas na incidência de cercosporiose (Cercospora coffeicola) e bicho-mineiro (Leucoptera coffeella) em cultivares de cafeeiros em Monte Carmelo, Minas Gerais, Brasil

O material genético adaptado às condições do Cerrado Mineiro e o monitoramento pode ser um fator determinante para o manejo eficiente de pragas e doenças do cafeeiro. Neste contexto, objetivou-se avaliar as condições climáticas na incidência de cercosporiose e bicho-mineiro em cultivares de cafeeiros na região de Monte Carmelo, Minas Gerais. O experimento foi conduzido na Universidade Federal de Uberlândia, Campus Monte Carmelo. O delineamento experimental utilizado foi em blocos casualizados, com quatro blocos, e os tratamentos foram constituídos por oito cultivares de Coffea arabica L.: Acaiá Cerrado MG-1474; Mundo Novo IAC 379-19; Bourbon Amarelo IAC J10; Catuaí Vermelho IAC 99; Paraíso MG H 419-1; Topázio MG-1190; Acauã Novo e IAC 125 RN. Cada parcela experimental foi constituída por 10 plantas, sendo avaliadas as cinco plantas centrais. Foi avaliada mensalmente a presença de lesões de cercosporiose no ramo localizado no terço superior pelo método não destrutivo. Foram contabilizadas quinzenalmente o número de folhas com minas intactas de bicho-mineiro no ramo plagiotrópico selecionado no terço médio. A incidência de cercosporiose e bicho-mineiro foi avaliada no período entre dezembro de 2017 a agosto de 2018. As cultivares que apresentaram menor incidência de bicho-mineiro foram Mundo Novo IAC 379-19, Acaiá Cerrado MG-1474, Bourbon Amarelo IAC J10, Paraíso MG H 419-1 e Topázio MG-1190, respectivamente. A maior incidência de bicho-mineiro ocorreu no período de abril até agosto. Os meses que apresentaram maior incidência de cercosporiose foram de dezembro a maio, havendo variabilidade da ocorrência da doença entre as cultivares testadas.

ADUBAÇÃO NITROGENADA E POTÁSSICA E SUA RELAÇÃO COM A INCIDÊNCIA DE CERCOSPORIOSE E FERRUGEM EM CAFEEIRO FERTIRRIGADO

O cafeeiro apresenta suscetibilidade a várias doenças, no entanto, as de maior importância e agressividade são a ferrugem, causada pelo fungo Hemileia vastatrix e a cercosporiose, cujo agente etiológico é o fungo Cercospora coffeicola. Objetivou-se avaliar a incidência de cercosporiose e ferrugem em cafeeiro fertirrigado com doses de nitrogênio e potássio na região de Monte Carmelo-MG. O trabalho foi conduzido na Fazenda Juliana, município de Monte Carmelo-MG. O plantio da lavoura foi realizado em novembro de 2011, utilizando-se mudas da cultivar Topázio MG 1190. Os tratamentos constaram de cinco níveis de N e K2O, correspondentes a 30, 80, 130, 180 e 230% do recomendado para lavouras não irrigadas aplicados via fertirrigação. O parcelamento da adubação foi realizado em doze vezes iguais no ano, referente a uma fertirrigação por mês. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições. Cada parcela foi composta por 10 plantas, consideradas úteis as oito centrais. No período de março de 2015 a fevereiro de 2016, foi mensurado mensalmente a incidência da cercosporiose nas folhas e frutos e a incidência de ferrugem nas oito plantas úteis de cada parcela experimental. O nível de adubação de 30% do recomendado para lavouras cafeeiras favoreceu maior incidência de cercosporiose nos frutos. Os diferentes níveis de adubação não influenciaram na ocorrência da ferrugem ao longo do período avaliado.

The Toxin Cercosporin is a Virulence Factor for Infection of Coffee by Cercospora coffeicola

ABSTRACTBrown eye spot, caused by Cercospora coffeicola, causes significant losses in both quality and quantity of coffee production. As many Cercospora spp. produce the photoactivated toxin cercosporin, this study aimed to determine the role of cercosporin in C. coffeicola pathogenesis by creating disruption mutants unable to produce the toxin. Six C. coffeicola isolates from Brazilian fields, representing organic and conventional production systems in the Minas Gerais state, were evaluated for their ability to produce cercosporin in vitro. Toxin production varied among isolates, ranging from 3.5 – 25.3 µM/ 5 mm mycelial plug; production was undetectable in one isolate. The C. coffeicola homolog of the polyketide synthase gene (CTB1) involved in cercosporin production was amplified using a degenerate primer strategy. The 7044 nt ccCTB1 gene sequence was 90.3% identical to the cnCTB1 gene in Cercospora nicotianae and encoded a putative protein of 2196 amino acids with 98.2% similarity and 97.5% identity to its counterpart in C. nicotianae. Transformation of two isolates of C. coffeicola with a CTB1 disruption construct resulted in the recovery of six ctb1 disruption mutants. All of the ctb1 disruptants were deficient in cercosporin production. Disruption mutants did not differ significantly from the wild type for either growth or sporulation, but were significantly altered in virulence on coffee. As compared to wild type, time to lesion development was significantly increased and numbers of lesions were significantly decreased in coffee plants inoculated with ctb1 disruption mutants. These results show that cercosporin toxin is a virulence factor for C. coffeicola infection of coffee.

PHIALOMYCES MACROSPORUS REDUCES CERCOSPORA COFFEICOLA SURVIVAL ON SYMPTOMATIC COFFEE LEAVES

<p>Saprobe fungi and necrotrophic pathogens share the same niche within crop stubble and the search for fungi non-pathogenic to plants that are able to displace the plant pathogens from its overwintering substrate contributes to the disease management. Brown eye spot (<em>Cercospora coffeicola</em>) is among the most important coffee diseases, it is caused by a necrotrophic pathogen that has decaying leaves as its major source of inoculum. We have screened saprobe fungi for the ability to reduce <em>C. coffeicola</em> sporulation and viability and determined the possible mechanisms involved in the observed biocontrol. A selected saprobe fungus, <em>Phialomyces macrosporus</em>, reduced the pathogen’s viability by 40% both <em>in vitro</em> and <em>in vivo</em>. The fungus acts through antibiosis and competition for nutrients. It produced both volatile and non-volatile compounds that inhibited <em>C. coffeicola</em> growth, sporulation, and viability. It also produced the tissue maceration enzyme (polygalacturonase), which reduces the pathogen both in detached leaves or in planta. The reduction in the fungal viability either by the saprobe fungus or its polygalacturonase-fraction supernatant resulted in the reduction of the disease rate. Therefore, <em>P. macrosporus </em>is a potential microbial agent that can be used in an integrated management of brown eye spot through the reduction of the initial inoculum of the pathogen that survives and builds up in infected leaves.</p><p> </p>

IDENTIFIKASI HAMA DAN PENYAKIT PADA TANAMAN KOPI DI KEBUN PERCOBAAN FAKULTAS PERTANIAN UNIVERSITAS WINAYA MUKTI

Kopi merupakan komoditas andalan ekspor bagi Indonesia. Akan tetapi dari segi mutu, masih jauh tertinggal dengan negara lain. Salah satu penyebab rendahnya mutu kopi adalah banyaknya serangan hama dan penyakit di lapangan sehingga menurunkan produksi dan kualitas biji kopi yang dihasilkan. Tujuan dari penelitian ini adalah untuk mengidentifikasi hama dan penyakit yang menyerang tanaman kopi, sehingga dapat dikendalikan secara tepat. Penelitian ini dilaksanakan di Kebun Percobaan Fakultas Pertanian Universitas Winaya Mukti dari bulan April – Juni 2018. Pengambilan sampel tanaman secara acak dengan Metode Random Sampling. Hasil penelitian menunjukkan bahwa hama yang banyak menyerang tanaman kopi adalah kutu daun hijau (Coccus viridis) dan kutu dompolan (Planococus sp), penyakit yang banyak meyerang adalah penyakit karat daun (Hemileia vastatrix), penyakit embun jelaga (Capnodium sp) dan penyakit bercak daun (Cercospora coffeicola), kebersihan areal perkebunan sangat mempengaruhi perkembangan populasi hama dan penyakit tersebut.