Insights into the Isolation, Identification, and Biological Characterization Analysis of and Novel Control Strategies for Diaporthe passiflorae in Postharvest Passion Fruit.

Postharvest diseases seriously restrict developments in the passion fruit industry. In this study, we aimed to identify the postharvest pathogen affecting passion fruit, investigate its pathogenicity, and explore relevant control methods. The pathogen was isolated from rotting passion fruit and identified using morphological characteristics, ITS sequences, and phylogenetic tree analyses. Additionally, preliminary studies were conducted to assess the biological characteristics of the pathogen and evaluate the efficacy of various treatments for disease control. The fungus on the passion fruit called B4 was identified as Diaporthe passiflorae. Optimal conditions for mycelial growth were observed at 25-30 °C and pH 5-6, with starch as the carbon source and peptone as the nitrogen source. Infection by D. passiflorae accelerated fruit decay, reduced the h° value of the peel, and increased the peel cell membrane permeability when compared to the control. Notably, treatments with appropriate concentrations of ɛ-poly-l-lysine, salicylic acid, and melatonin showed inhibitory effects on the pathogen's growth in vitro and may thus be potential postharvest treatments for controlling brown rot caused by D. passiflorae in passion fruit. The results provide a scientific basis for the development of strategies to control postharvest decay and extend the storage period of passion fruit.

Resistance to diseases of sour, sweet and wild passion fruit genotypes

The cultivation of passion fruit is important for Brazil, since the country is currently the largest producer and consumer of fruit in the world. However, the fields of passion fruit still face important problems due to the incidence and severity of diseases in the field. Thus, the present study aimed to assess resistance to bacterial and fungal diseases in 13 genotypes of sour, sweet and wild passion fruit, in field conditions in the Distrito Federal, Brazil. For this, a field experiment was installed in a randomized block design, with four replications and 13 treatments (genotypes). The characteristics of incidence, severity and degree of resistance for bacteriosis, septoriosis, scab and anthracnose diseases were evaluated in 5 fruits per plot of each genotype. Genetic parameters of the evaluated traits were also estimated. High heritability values and CVg/Cve ratio were observed for most of the evaluated characteristics. The genotypes presented mean values of incidence and severity of bacteriosis, septoriosis, scab and anthracnose different among them, and the one that presented the best results in the degree of resistance for all diseases was F1 (MAR20 # 24 x ECL7 P1 R4).

Assessment of resistance of hybrids and lineages of passion fruit to bacteriosis under protected cultivation / Avaliação da resistência de híbridos e linhagens de maracujazeiro à bacteriose sob cultivo protegido

Yield and longevity of yellow passion fruit have been reduced by diseases such as the bacterial spot caused by Xanthomonas axonopodis pv. passiflorae. Genetic resistance has been confirmed as the most efficient and economical correct option to minimize this disease problem. Aiming at it, the objective of this research was to evaluate the incidence, severity and progression of the disease in 12 genotypes of sour passion fruit, in seedling stage in nursery greenhouse after inoculation of Xanthomonas axonopodis pv. passiflorae. The inoculation was performed with an isolate collected in the Pipiripau Rural Nucleus, Brasilia-DF, named UnB-1397 (1x106 CFU/mL), through induction of injuries. There were performed four assessments, with interval of 7 days except the first which was performed 11 days after inoculation. The incidence was estimated by the percentage of plants affected. To evaluate the severity, it was used the diagrammatic scale validated by Costa et al. (2018), with adaptations, using the measurement of the affected area by necrotic lesions on the leaf. All genotypes were susceptible to bacteriosis, 5 being considered moderately susceptible: F1BRS Pérola do Cerrado x Rosa Intenso, Mar20#21, Mar20#15b, Mar20#24xMar20#40 and FB200PL4R2 x Mar20#2005, with a mean of severity ranging from 11 to 25% of injured area in leaves.

A produtividade e a longevidade dos pomares de maracujazeiro-azedo têm sido comprometidas em razão de doenças como a bacteriose, causada por Xanthomonas axonopodis pv. passiflorae. A resistência genética tem se confirmado como a opção mais eficiente e econômica para minimizar tal problema. Dessa forma, o objetivo deste trabalho foi avaliar a reação de 12 genótipos de maracujazeiro, em fase de mudas, sob cultivo protegido, à Xanthomonas axonopodis pv. passiflorae. A inoculação com isolado denominado UnB-1397 (1x106 CFU/mL),coletado no Núcleo Rural de Pipiripau, Brasília-DF, se deu pela indução de ferimentos. Foram realizadas 4 avaliações, com intervalo de 7 dias, sendo a primeira avaliação realizada 11 dias após a inoculação. A incidência foi estimada pela porcentagem de plantas afetadas. Para avaliação da severidade, foi utilizada escala diagramática validada por Costa et al. (2018), com adaptações, utilizando-se a mensuração da área foliar atingida por lesões nas folhas. Todos os genótipos se mostraram suscetíveis à bacteriose, sendo 5 considerados moderadamente suscetíveis: F1 BRS Pérola do Cerrado x Rosa Intenso, Mar20#21, Mar20#15b, Mar20#24 x Mar20#40 e FB200PL4R2 x Mar20#2005, apresentando uma média de severidade que variou de 11 a 25% de área ou tecidos foliares lesionados.

Development and validation of a standard area diagram set as assessment aid for estimating the severity of bacterial spot on tri-lobed leaves of yellow passion fruit / Desenvolvimento e validação de escala diagramática como auxílio na avaliação da severidade da bacteriose em folhas trilobadas do maracujazeiro azedo

Bacterial spot (Xanthomonas axonopodis pv. passiflorae) significantly reduces yellow passion fruit (Passiflora edulis Sims) yield and longevity. A standard area diagram set (SADs) for severity assessment of bacterial spot on tri-lobed leaves of yellow passion was developed and validated in this study. The SADs consisted of eight severity levels (2; 4; 9; 18; 35; 58; 80; and 94%). For its validation, 20 raters, who initially estimated the disease severity without the aid of the SADs, were divided into four groups (G1 and G3, inexperienced; G2 and G4, experienced). Subsequently, G1 and G2 performed the second evaluation without the SADs, and G3 and G4 completed the second evaluation with the proposed SADs. The accuracy and precision of the assessments were determined by simple linear regression and by the Lin's concordance correlation coefficient (LCCC). The proposed SADs allowed accurate and precise quantification of bacterial spot severity, increasing the agreement between estimated and actual values. Inexperienced raters benefited the most from the use of the SADs. The increase in accuracy and precision in the non-aided groups, when present, was less pronounced than those increments observed in the SADs-aided groups. The LCCC confirmed the increases in accuracy and precision detected by the linear regression analysis.

A bacteriose (Xanthomonas axonopodis pv. passiflorae) reduz significativamente a produção e longevidade do maracujazeiro azedo (Passiflora edulis Sims). Uma escala diagramática para a avaliação da severidade da bacteriose em folhas trilobadas do maracujazeiro azedo foi desenvolvida e validada neste estudo. A escala diagramática apresentou oito níveis de severidade (2; 4; 9; 18; 35; 58; 80 e 94%). Para a sua validação, os 20 avaliadores foram divididos em quatro grupos (G1 e G3, sem experiência; G2 e G4, com experiência), que inicialmente estimaram a severidade da doença sem auxílio da escala. Posteriormente, G1 e G2 fizeram outra avaliação sem escala, e G3 e G4 realizaram a avaliação com a escala proposta. A acurácia e a precisão das estimativas foram determinadas por regressão linear simples e pelo coeficiente de correlação de concordância de Lin (LCCC). A escala diagramática proposta permitiu quantificar a severidade da bacteriose de forma acurada e precisa, aumentando a concordância entre os valores estimados e os reais. Os avaliadores inexperientes foram os mais beneficiados pelo uso da escala. O aumento da acurácia e precisão nos grupos que realizaram dupla avaliação sem escala, quando ocorreu, foi mais discreto que os incrementos observados nos grupos que utilizaram a escala. O LCCC confirmou os incrementos da acurácia e precisão detectados pela análise de regressão linear.

Reaction of yellow passion fruit to passion fruit woodiness disease and to bacterial spot / Reação de maracujazeiro azedo à virose do endurecimento dos frutos e à bacteriose

The use of resistant varieties is a promising strategy for passion fruit woodiness disease (PWD) (Cowpea aphid-borne mosaic virus - CABMV) and bacterial spot (Xanthomonas axonopodis pv. passiflorae - Xap) control in yellow passion fruit (Passiflora edulis Sims). This study aimed at evaluating the reaction of nine genotypes of yellow passion fruit to both mechanically inoculated CABMV and Xap, under protected cultivation. The experiment was conducted using a randomized block design with subdivided parcels comprised of nine treatments, four repetitions, six replications per genotype, and five evaluations. Disease incidence (% plants infected) and severity (% of total leaf area with necrotic lesions or leaf symptoms) were calculated at 7-day intervals. All genotypes evaluated were classified as moderately susceptible to PWD. MAR20#10, MAR20#41, and Rosa Intenso were classified as moderately resistant to bacterial spot whereas the remaining genotypes were classified as moderately susceptible. Genotypes Rosa Intenso, MAR20#41, MAR20#15, and MSCA stood out for presenting the lowest PWD mean severity scores as well as the greatest numbers of plants presenting resistance to PWD after five evaluations. MAR20#10, MAR20#41, and Rosa Intenso demonstrated the lowest bacterial spot mean severity scores. Among the genotypes selected, Rosa Intenso and MAR20#41 were the most promising genotypes for presenting the lowest severity scores for both PWD and bacterial spot disease.

O uso de variedades resistentes é uma estratégia promissora para o controle da virose do endurecimento dos frutos (VEF) (Cowpea aphid-borne mosaic virus - CABMV) e da bacteriose (Xanthomonas axonopodis pv. passiflorae - Xap) no maracujazeiro amarelo (Passiflora edulis Sims). Este estudo objetivou avaliar a reação de nove genótipos de maracujazeiro amarelo à CABMV e Xap, ambos inoculados mecanicamente, sob cultivo protegido. O experimento foi conduzido em delineamento de blocos casualizados com parcelas subdivididas, composto por nove tratamentos, quatro repetições, seis plantas por genótipo e cinco avaliações. A incidência (% plantas infectadas) e a severidade (% da área foliar total com lesões necróticas ou sintomas foliares) das doenças foram calculadas em intervalos de sete dias. Todos os genótipos avaliados foram classificados como moderadamente suscetíveis à VEF. MAR20#10, MAR20#41 e Rosa Intenso foram classificados como moderadamente resistente à bacteriose enquanto os demais genótipos foram classificados como moderadamente suscetíveis. Os genótipos Rosa Intenso, MAR20#41, MAR20#15 e MSCA se destacaram por apresentarem menores severidades médias da VEF bem como pelo maior número de plantas apresentando resistência à virose após as cinco avaliações. MAR20#10, MAR20#41 e Rosa Intenso demonstraram as menores severidades médias de bacteriose. Entre os genótipos selecionados, Rosa Intenso e MAR20#41 foram os mais promissores por apresentarem os menores valores de severidade para a VEF e para a bacteriose.

Genótipos de maracujazeiro-azedo com resistência à bacteriose / Genotypes of passionfruit to resistance to the bacteriose

Este trabalho teve como objetivo avaliar e selecionar genótipos de maracujazeiro-azedo com resistência à bactéria Xanthomonas axonopodis pv. passiflorae. Para a inoculação da bactéria, nas folhas das plantas, foi empregado o método da agulha utilizando-se o delineamento de blocos casualizados, com 4 repetições e 12 plantas por parcela, em esquema de parcela subdividida, com quatro épocas de avaliação na parcela e 18 genótipos na subparcela. Foi avaliada a incidência e a severidade da bacteriose, com base em escala de notas variando de 0 a 4, onde foram classificadas como Resistentes, Medianamente Resistentes, Medianamente Suscetíveis, Suscetíveis e Altamente Suscetíveis. Os genótipos apresentaram variabilidade com relação à resistência, sendo que os genótipos Maracujá Moranga, RC-0-3, Vermelhinho e PES-7 foram selecionados, pois apresentaram mais de 30% de plantas medianamente resistentes na última avaliação. O genótipo MSCA foi considerado resistente com base na severidade. As plantas individuais dos diferentes genótipos que permaneceram resistentes até a última avaliação foram selecionadas e deverão ser novamente avaliadas para a confirmação da resistência à bactéria Xanthomonas axonopodis pv. passiflorae, incluindo diferentes isolados desta bactéria.

This work had as objective to evaluate and to select the reaction of passionfruit genotypes to Xanthomonas axonopodis pv. passiflorae. For the inoculation of the bacterium had been used of the needle. Twelve plants of each of 18 genotypes were evaluated in a randomized block experiment with 4 replicates and four different times of evaluation. It was evaluated the incidence and the severity of bacteriose, on the basis of a note scale of 0 the 4 which were classified as Resistant, Medium Resistant, Medium Susceptible, Susceptible and Highly Susceptible. The genotypes had presented variability with regard to the resistance, being that the genotypes Maracujá Moranga, RC-0-3, Vermelhinho and PES-7 had been selected, since they had more than presented 30% of medium resistant plants in the last evaluation. Only one genotype was considered resistant, on the basis of severity. The individual plants of the different genotypes that had remained resistant until the last evaluation will have to be selected and evaluated for the confirmation of the Xanthomonas axonopodis pv. passiflorae.

Incidência e severidade de septoriose (septoria passiflorae sydow) em mudas de 48 genótipos de maracujazeiro azedo, sob casa de vegetação no distrito federal / Incidence and severity of septoriosis (septoria passiflorae) in seedling of 48 genotypes of passionfruit (passiflora edulis f. flavicarpa) growing in greenhouse at distrito federal

O maracujazeiro é atacado por diversos patógenos, entre eles o fungo Septoria passiflorae, causador da septoriose. Objetivando-se analisar a reação de genótipos de maracujá azedo a septoriose, foi conduzido um experimento com mudas, em casa de vegetação, na Estação Biológica da Universidade de Brasília, em blocos casualizados com quatro repetições e 6 plantas por parcela, testando-se 48 genótipos. A inoculação do patógeno foi feita por aspersão na planta com, suspensão contendo concentração de 5,0 x 106 esporos/ml, produzidos em meio de cultura. Foram feitas duas avaliações, com intervalos de 25 dias. As plantas foram avaliadas de acordo com a escala de notas de 1 a 4, sendo 1 para Plantas sem sintomas; 2 ? Lesões esparsas nas folhas; 3 ? Lesões coalescendo tomando mais de 25 % do limbo foliar; 4 ? Planta com desfolha. Houve diferenças significativas entre os genótipos para todos os parâmetros avaliados. Destacaramse os genótipos MAR 20-09, MAR 20-53 e MAR 20-60, como mais resistentes a septoriose em condições de cultivo protegido, enquanto os genótipos MAR 20-43, MAR 20-39 e MAR 20-01 foram os mais suscetíveis. (AU)

Passionfruit is affected by many diseases caused by pathogenic fungi. One of them is Septoria passiflorae, causing septoriosis. In order to evaluate the reaction of Passionfruit genotypes to septoriosis, an essay was carried out in greenhouse conditions in the experimental station of Universidade de Brasília. It was designed by randomized blocks with four replications and six plants per plot. A number of 48 genotypes were tested. The inoculation was done by spraying a suspension of conidia at 5,0 x106 spores/ml. Six evaluations were done, at 7 days intervals. The scores were done using a lesion scale graded from 1 to 4, 1- no visual disease, 2-spread lesions on the leaves, 3- coalescent lesions with more than 25% of leaf surface, 4-falling leaves. The plants had small significant differences between the averages of grades, so there was little reduction of grades from first to second evaluation time (50 days), probably by theincrease of leaf area. The genotypes MAR 20-09, MAR 20-53 and MAR 20-60, were considered resistant to septoriosis at greenhouse conditions, and the MAR 20-43, MAR 20-39 e MAR 20-01 were more susceptible. (AU)