Comparative Efficacy of Aloe vera (Linn) and Aloe schweinfurthii (Baker) Powdered Leaf Extracts in the Control of Some Plant Fungal Pathogens

Evaluation of the relative efficacy of powdered leaf extracts of Aloe vera(Linn) and Aloe schweinfurthii(Baker) in the control of some plant pathogens was undertaken in this work. Antimicrobial activities ofthe extracts obtained using cold water, hot water and ethanol were tested against four fungal spp., namely, Alternaria solani,Colletotrichum lindemuthianum, Sclerotium rolfsiiand Trichophyton rubrum. The phytochemical screening of the leaf extracts of the two aloe species revealed the presence of bioactive compounds such as alkaloids, tannins, saponins, flavonoids, cardiac glycosides, phytates and oxalates. The extracts were observed to exhibit varying inhibitory effects on the selected fungi. Ethanolic extract of A. veraat 50mg/ml and 100mg/ml had the greatest impact on A. solaniand C. lindemuthianum respectively.Similarly, cold water extract of A. schweinfurthiiat 100mg/ml was the most effective against S. rolfsiiandT. rubrum.However, hot water extract of A. vera wasleast effective against C. lindemuthianum. Also, the efficacy of cold water extract of A. schweinfurthii at 50mg/mlwas very low against T. rubrumand A. solani. The hot water extract of A. schweinfurthii at 20mg/ml also showed the least effect against S. rolfsii. Consequently, extracts from both Aloe species can be recommended in the management of the four fungal pathogens evaluated in this study. It is hoped that in no distant future, botanical fungicides would be developed from the two Aloe species

Durabilidade da resistência induzida por ulvana e efeito da concentração de inóculo no controle da antracnose do feijão / Persistence of ulvan-induced resistance and effect of inoculum concentration in the control of bean anthracnose

O presente trabalho teve por objetivo avaliar a duração da resistência induzida, a eficiência do número e intervalo de aplicações de ulvana, bem como a influência de diferentes concentrações de inóculo no controle e na severidade da antracnose do feijão. Para tanto, foram realizados três experimentos independentes. Plantas de feijão (P. vulgaris, cv. Uirapuru) foram cultivadas em condições de casa-de-vegetação e, no primeiro experimento, foram pulverizadas com ulvana em uma única aplicação aos: nove dias antes da inoculação (dai) V3(i); seis dai V3(m); três dai V3(f); ou duas aplicações consecutivas realizadas aos nove e seis dai V3(i)/(m); nove e três dai V3(i)/(f) ou seis e três dai V3(m)/(f) e inoculadas em um mesmo momento. No segundo e terceiro experimentos, plantas de feijão foram tratadas duas vezes (seis e três dai) e inoculadas em diferentes momentos ou com diferentes concentrações de inóculo, respectivamente. A pulverização de ulvana reduziu a severidade da antracnose em cerca de 50%. Duas aplicações de ulvana foram mais eficientes em induzir respostas de defesa em feijão contra a antracnose que somente uma. A maior redução (96%) da doença ocorreu com pulverizações sucessivas em V3(m)/(f). O efeito de duas aplicações do polissacarídeo persistiu até nove dias após o tratamento. A redução na severidade da antracnose foi maior quando foram utilizadas concentrações intermediárias de inóculo (105 e 106 conídios por mL).

The present work aimed to evaluate the persistence of the induced resistance, the efficiency of the number and the interval of ulvan applications and the influence of different inoculum concentrations in the control of bean anthracnose. Three independent experiments were carried out. Bean plants (P. vulgaris, cv. Uirapuru) were cultivated under green house conditions and, in the first experiment, they were treated with ulvan once at nine days before inoculation (dbi) V3(i); six dbi V3(m) or three dbi V3(f) or they were treated twice at nine and six dbi V3(i)/(m); nine and three V3(i)/(f) or six and three (dbi) V3(m)/(f), the they were inoculated at the same time. In the second and third experiments, bean plants were treated twice (six and three dbi) then inoculated in different moments or with different inoculums concentrations, respectively. The application of ulvan reduced the anthracnose severity by 50%. Two ulvan applications were more efficient in inducing defense responses in bean plants than a single application. The highest disease reduction (96%) was achieved by spraying ulvan twice at V3(m)/(f). The effect of two applications persists until nine days after the treatment. The reduction on the anthracnose severity was higher when intermediate (105 e 106 conidia per mL) inoculum concentrations were used.

Vegetative compatibility and heterokaryon formation between different isolates of Colletotrichum lindemuthianum by using the nit mutant system

Colletotrichum lindemuthianum, the causative agent of bean anthracnose, is one of the most common pathogens leading to expressive damage to plants beyond presenting noticeable variability. The knowledge on vegetative compatibility groups (VCGs) is of particular interest in asexual fungi as they subdivide the population in groups that can exchange genetic information via heterokaryosis and the parasexual cycle. Among the techniques used in studies about vegetative compatibility groups, the obtainment of nit mutants is apparent. This paper is aimed at obtaining heterokaryons between different isolates of C. lindemuthianum, grouping them in VCGs and evaluating their genetic variability by using the nit mutants system. Nit mutants were obtained from 20 single spore isolates. The mutants were phenotypically classified and paired for complementation and formation of heterokaryons so as to group them in VCGs. Seventeen mutants from the different phenotypic-rates were recovered: nit1, nit2, nit3 and nitM. At the same time, 10 mutants were selected for pairing and division of the anastomosis groups. Nine heterokaryons were obtained and the isolates were divided into 9 vegetative compatibility groups. In the combinations for the formation of anastomosis, 31 compatible combinations and 24 incompatible combinations were observed. It was concluded that the methodology used to select nit mutants in C. lindemuthianum made it possible to determine the vegetative compatibility groups and that such a technique was adequate to prove genetic variability.

Seleção de linhagens de feijoeiro com tipo de grão carioca e com os alelos co-4 e co-5 de resistência à antracnose / Selection of common bean strains with carioca grain type, and with the alleles co-4 and co-5 for anthracnose resistance

Objetivou-se, neste trabalho, identificar linhagens de feijão que reúnam, além da resistência à antracnose, alta produtividade de grãos do tipo carioca e resistência à mancha angular. Foram utilizadas 194 linhagens F5:6 extraídas de sete famílias segregantes, selecionadas do cruzamento entre os genitores H147 e B1. A linhagem H147 possui grãos tipo carioca, portadora do alelo Co-5, que confere resistência a várias raças de Colletotrichum lindemuthianum. A linhagem B1 também possui grãos tipo carioca e é portadora do alelo Co-4, que confere resistência a outro grupo de raças do mesmo patógeno. As linhagens foram avaliadas na safra das águas 2005/2006, em Lavras, com a cultivar Talismã e H147 como testemunhas, com base na produtividade e tipo de grãos. Foram selecionadas 99 linhagens, as quais foram avaliadas na safra da seca/2006, juntamente com a testemunha Talismã, com base na produtividade, tipo de grão e resistência à mancha angular. Dessas 99 linhagens, foram selecionadas 24, as quais foram avaliadas na safra de inverno/2006 em Lavras e Lambari, com base no tipo de grão e produtividade. Essas 24 linhagens foram inoculadas com a raça 321 de C. lindemuthianum, que quebra a resistência conferida pelo alelo Co-4, mas não o Co-5. Para verificar a presença do alelo Co4 foi utilizado um marcador SCAR que amplifica um fragmento de 950 pb por meio do primer SAS 13. Foi possível identificar 14 linhagens que possuem a pirâmide de alelos Co-4/Co-5 e entre elas, quatro destacaram-se em todos os caracteres avaliados.

The objective of the research was to identify bean strains that possess at the same time resistance to anthracnose, high grain yield of Carioca grain type and resistance to angular leaf spot. 194 strains F5:6 were taken from seven segregating families derived from the cross H147 x B1. The H147 line has Carioca grain type and Co-5 resistance allele to several races of C. lindemuthianum. The B1 line also has the Carioca grain type, and the Co-4 resistance allele against others races of the same pathogen. The strains were evaluated in the spring/summer (2005/2006) in the municipality of Lavras, in the Southern of the State of Minas Gerais, with the Talismã cultivar and H147 line as check, based mainly on grain type and grain yield. 99 strains, together with the Talismã check, were selected and evaluated based on grain yield, grain type and angular leaf spot resistance in the summer (2006) in the same place. From these 99 strains, 24 strains were selected and evaluated in the winter/spring (2006) in two places, Lavras and Lambari, based on the type of grain and productivity, and using the same check. Those 24 strains were also inoculated with the race 321 of C. lindemuthianum that break the resistance of the Co-4 allele, but not of the Co-5. The SCAR marker using the SAS13 primer was used to detect the presence of the Co-4 allele. Fourteen strains were identified that have the Co-4/Co-5 allele pyramid, and, among them, four stand out in all evaluated features.

Intensity of angular leaf spot and anthracnose on pods of common beans cultivated in three cropping systems / Intensidade da mancha-angular e da antracnose em vagens de feijão em três sistemas de cultivo

With the purpose to evaluate the intensity of angular leaf spot (ALS) and anthracnose (ANT) on pods, nine genotypes of common bean were planted in three cropping systems: monocrop (MC), monocrop grown on trellises (MCT), and intercrop with maize (ICM). In MC, beans were planted 0.5 m apart. Trelisses were set up with 1.8 m high bamboos and beans were sown 0.65 m apart. In ICM, beans were planted simultaneously with maize and in its rows. This cereal was sown 1.0 m apart with four plants per meter. Each cropping system was an independent trial installed close to each other. Climbing genotypes of beans most susceptible to ALS had less diseased pods in ICM than in both MC and MCT, but the less susceptible genotypes, regardless of their growth type, as well as the susceptible bush and semiclimbing genotypes, were similarly attacked by ALS in the three systems. ANT on pods of the susceptible bean cv. Pérola was less intense in MCT than in MC, and less intense in ICM than in MCT. ANT seed transmission was 11 percent, 9.1 percent, and 4.4 percent when seeds come from MC, MCT, and ICM, respectively.

Com o objetivo de avaliar a intensidade da mancha-angular (MA) e da antracnose (ANT) em vagens, nove genótipos de feijão foram plantados em três sistemas de plantio: monocultivo (MC), monocultivo com tutoragem artificial (MCT) e consórcio com milho (CCM). No MC, o feijão foi semeado no espaçamento entre fileiras de 0,50 m. Para o MCT, utilizaram-se varas de bambu formando "Vs" invertidos com 1,8 m de altura, nos quais foi mantido o espaçamento entre fileiras de 0,65 m na base. No CCM, o feijão foi plantado simultaneamente ao milho e em suas fileiras. Esse cereal foi semeado no espaçamento de 1,0 m, com quatro plantas por metro. Cada sistema de cultivo foi um ensaio independente, todos instalados na mesma área. Os genótipos trepadores mais suscetíveis à MA apresentaram menos vagens doentes no CCM que no MC e MCT, mas os genótipos menos atacados pela MA, independentemente do tipo de crescimento, como também os outros genótipos suscetíveis de porte anão e semitrepador, foram infectados de forma semelhante nos três sistemas de plantio. A ANT nas vagens do cv. Pérola foi menos intensa no MCT que no MC, e menos intensa no CCM que no MCT. A transmissão da ANT pela semente foi de 11 por cento, 9,1 por cento e 4,4 por cento quando as sementes foram colhidas no MC, MCT e CCM, respectivamente.

Seleção de famílias de feijão com resistência à antracnose, produtividade e tipo de grão carioca / Selection of common bean families for resistance to anthracnose, grain yield and carioca grain type

Na obtenção de cultivares de feijão com resistência à antracnose, outros atributos agronômicos também devem ser considerados para atender a preferência do consumidor e do produtor. Neste trabalho, objetivou-se identificar famílias de feijão que reúnam, além da resistência à antracnose, alta produtividade, grãos tipo Carioca e porte ereto. Foram cruzados os genitores CNFC 10706, B1 portador do alelo de resistência à antracnose Co-4 e H147 portador do alelo de resistência Co-5. Os três possuem grãos semelhantes ao Carioca. Inicialmente foram avaliadas 224 famílias F2:3, derivadas dos três cruzamentos, mais a cultivar Talismã como testemunha, no inverno/primavera de 2004, em Lavras, com base no tipo de grão. Foram selecionadas 99 famílias F2:4 e avaliadas com a testemunha Talismã, na seca de 2005 em Lavras e Lambari. Essas 99 famílias foram também inoculadas com as raças 593 e 337 de C. lindemuthianum, para auxiliar na seleção daquelas portadoras dos alelos de resistência Co-4 e Co-5. As 35 famílias F2:5 remanescentes, foram avaliadas no inverno/primavera de 2005, em Ijaci, MG. Em todos os experimentos foi utilizado, o delineamento látice quadrado. As 35 famílias foram novamente inoculadas com as raças 65 e 321. Por meio das inoculações e também com o uso de um marcador molecular SCAR ligado ao alelo Co-4, foi possível identificar a constituição genética da maioria das 35 famílias quanto à reação antracnose e selecionar quatro que reúnem, simultaneamente, tipo de grãos semelhante ao Carioca, porte ereto e boa produtividade, além de serem portadoras dos alelos Co-4 e Co-5 de resistência à antracnose.

In the common bean breeding, besides anthracnose resistance other agronomical traits need to be considered for achieving the producer and consumer requirements. So the aims of this research were to select common bean families resistant to anthracnose, high grain yield, Carioca grain type and upright plant type. The lines CNFC 10706, B1 and H147 were crossed. All of them have Carioca grain type. The B1 line is resistant to anthracnose due to the Co-4 allele, and the H147 due to the Co-5 allele. From the CNFC 10706 x H147, CNFC 10706 x B1 and H147x B1, 224 F2:3 families plus the check Talismã were evaluated in the winter/spring of 2004, in Lavras county, based on grain type. Ninety nine families were selected and evaluated, plus the check, in the "seca" of 2005 at Lavras and Lambari county. The families were also inoculated with the 337 and 593 races of C. lindemunthianum for selecting those with the Co-4 and Co-5 resistant alleles. The 35 selected families (F2:5) were evaluated in the winter/spring of 2005, in Ijaci county. The square lattice design was used in all experiments. Those 35 families were also inoculated with the 65 and 321 races of C. lindemunthianum. Through the inoculations and the Co-4 SCAR marker the genetic constitutions of most of the 35 families were identified. Four families were selected with Carioca grain type, upright plant type, high grain yield and besides bearing the Co-4 and Co-5 alleles for anthracnose resistance.

Melhoramento do feijoeiro comum com grão tipo carioca, visando resistência à antracnose e à mancha angular / Breeding of common bean with carioca type grain for the resistance to anthracnose and angular leaf spot

Objetivou-se no trabalho, selecionar linhagens de feijoeiro comum que reunissem, além da alta produtividade, porte ereto e grãos do tipo Carioca, também a resistência à antracnose e à mancha angular. O material experimental constituiu-se de 143 linhagens oriundas de três famílias segregantes F1:4RC2 {[(G2333 X ESAL 696) X ESAL 696] X CI 140}. Foram conduzidos quatro experimentos em três localidades da região sul de Minas Gerais, avaliando-se a produção, o tipo de grão, o porte e a reação à mancha angular. A reação à antracnose foi determinada a partir de inoculações de plantas jovens de cada linhagem, com as raças 2047 e 1545, mantidas em câmara de nevoeiro por três dias e transferidas para casa de vegetação com irrigação por aspersão, a cada quatro horas. Selecionaram-se quatro linhagens com alta produtividade, porte mais arbustivo, grãos tipo carioca e com resistência à mancha angular (nota até 4). Uma das linhagens selecionada possui o alelo Co-4², outras duas possuem o alelo Co-7 de resistência à antracnose e a última, embora seja suscetível à antracnose, possui resistência à mancha angular (nota 3,97) e maior produtividade de grãos.

Aiming to select common bean lines with high grain yield, Carioca grain type, upright plant habit and resistant to anthracnose and angular leaf spot, 143 lines were selected from three families of the cross F1:4RC2 {[(G2333 X ESAL 696) X ESAL 696] X CI 140}. The promising lines were selected based on the agronomical traits in four field experiments, set up in three places in Southern MG State using the square lattice design. The reaction of each line to the anthracnose was evaluated by inoculating the seedlings using the races 1545 and 2047, and kept in humid chamber during three days, and then moved to greenhouse with sprinkle irrigation every four hours. Four lines with high grain yield, upright plant habit, Carioca grain type, and resistance to angular leaf spot (score up to 4) were selected. Among them one of the lines has the Co-4² allele for anthracnose resistance, two lines have the Co-7 allele, and the last one, although susceptible do anthracnose, presented the highest grain yield and angular leaf spot resistance (score 3,97).

Influência das variáveis ambientais no progresso da antracnose do feijoeiro e eficiência de tiofanato metílico + clorotalonil no controle da doença / Influence of the environmental variables in the progress of anthracnose of bean and efficiency of thiophanate methyl + chlorothalonil in the control of the disease

Em Minas Gerais a antracnose destaca-se como uma das principais doenças foliares do feijoeiro comum, pela sua ocorrência em diversas épocas de plantio e redução na produção. No presente trabalho avaliou-se a ocorrência, o progresso da doença e a eficiência do controle químico da antracnose. Foram avaliadas parcelas com e sem tratamento fungicida (Tiofanato metílico + Clorotalonil, 240 + 600g i.a./ha) em cinco épocas de avaliação da doença em 24 plantios da cultivar carioca, de 04/96 à 03/97. Não se constatou a ocorrência da antracnose no período de fevereiro a março de 1997. O tratamento com fungicida resultou em menor severidade da doença e maior produção, principalmente nos meses de maior severidade dela. A severidade da doença correlacionou-se com as variáveis ambientais de temperatura máxima e mínima e umidade relativa aos 43, 57 e 71 dias após a emergência. Houve correlação negativa entre severidade da doença e produtividade do feijoeiro.

In Minas Gerais the anthracnose is one of the most important leaf diseases of the common bean due to occur at various planting time and to reduce the production. The present experiment was performed aiming to evaluate occurrence, progress of the disease and the efficiency of fungicide on the control of bean anthracnose. Plots with and without fungicide treatment (Thiophanate methyl + Chlorothalonil, 240 + 600g a. i./ha) were evaluated in five times of evaluation during 24 sowing times of bean cultivar Carioca, between April/96 and March/97. The occurrence of the anthracnose was not verified during february and march of 1997. Treatment with fungicide resulted in the lower disease severity and higher yield, mainly in the months of higher severity of the disease. There was significant correlation between the severity and the maximum and minimum temperature and relative humidity 43, 57 and 71 days after emergency. There was a negative correlation between severity of the disease and yelds.

Allelic relationships of anthracnose (Colletotrichum lindemuthianum) resistance in the common bean (Phaseolus vulgaris L.) cultivar Michelite and the proposal of a new anthracnose resistance gene, Co-11

The genetic resistance of Phaseolus vulgaris L. cultivar Michelite to races 8 and 64 of Colletotrichum lindemuthianum, causal agent of bean anthracnose, was characterized. Crosses were made between Michelite and Mexico 222 cultivars and the F2 population was inoculated with race 64 in order to study the inheritance of resistance to anthracnose in Michelite. The segregation of F2 population fitted in a ratio of 3R:1S, showing the presence of a dominant gene in Michelite gene conditioning resistance to race 64. Allelism tests were conducted with F2 populations derived from crosses between Michelite and AB 136, AND 277, BAT 93, Cornell 49-242, G 2333, Kaboon, Mexico 222, Michigan Dark Red Kidney (MRDK), Ouro Negro, Perry Marrow, PI 207262, TO, TU, and Widusa. All the cultivars (except Mexico 222) were resistant to race 64. While F2 derived from the Michelite x Mexico 222 was inoculated with race 8. Additionally, allelism tests indicated that the gene present in Michelite is independent from Co-1, Co-2, Co-3, Co-4, Co-5, Co-6, Co-7, Co-9 and Co-10 genes. The monogenic inheritance observed in Michelite and the independence of this gene from those previously characterized allow the authors to propose that the anthracnose resistant gene in Michelite should be named Co-11.