Sigatoka Disease Research Articles

Biomassa cítrica e fungicidas combinados com desfolha no controle da Sigatoka Amarela em banana “Prata”

Yellow sigatoka (Mycosphaerella musicola) is the main disease in banana areas in the Santa Catarina state. The objective of this research was to evaluate the effect of different methods of chemical and cultural control of sigatoka disease on Prata banana in subtropical climate. Six treatments were tested, evaluating three formulations (Tebuconazole 0,5 L ha-1 - Tiofanato metílico 0,6 L ha-1; Citric biomass 1,0 L ha-1; water) with or without leaf removal. The variables evaluated were under the curve of progress (AUDPC) and final gross sum (GSfinal) area. The experimental design was randomized blocks in factorial scheme with five repetitions. Treatments were compared with Duncan´s test (P<0,05). Significant differences were verified for products compared to control, but not for leaf removal. It was found that fungicides and citric biomass resulted in significant reductions in AUDPC and GS final when compared to control. Fungicides and citric biomass reduced area under disease progress curve by 65 and 63%, as well as final gross sum were 87 and 73%, respectively. Results showed small influence of leaf removal, but new studies should evaluate its influence with higher frequency of defoliation. Fungicides and citric biomass are efficient in controlling sigatoka.

Embriogénesis somática en el cultivar de plátano ‘FHIA – 25’ (AAB) a partir de ápices meristemáticos

<p>El cultivar de plátano ‘FHIA – 25’ (AAB), posee excelente rendimiento y alta resistencia a “Sigatoka negra”, pero con la limitante del bajo contenido de azúcar en su fruto, lo cual hace que sea necesario disponer de un método de regeneración de plantas a nivel celular como la embriogénesis somática, que se complemente a técnicas biotecnológicas de transformación genética para mejorar la calidad del fruto. El presente trabajo se realizó con el objetivo de establecer una metodología de regeneración vía embriogénesis somática a partir del explante inicial ápices de brotes axilares establecidos directamente en medio de cultivo líquido. Se obtuvieron suspensiones celulares embriogénicas homogéneas a partir del explante antes mencionado. Se lograron las mayores tasas de multiplicación a la densidad celular de 3,0%. La incubación de los embriones somáticos durante 30 días en el medio de cultivo de maduración permitió incrementar la germinación de los mismos. Durante la fase de aclimatización las plantas provenientes de los embriones somáticos, así como las plantas regeneradas por organogénesis, mostraron un alto porcentaje de supervivencia (98 y 97 %, respectivamente), sin la presencia de variación somaclonal.</p>

Spatial distribution of Yellow Sigatoka Leaf Spot correlated with soil fertility and plant nutrition

This study analyzed the spatial distribution of Yellow Sigatoka Leaf Spot relative to soil fertility and plant nutritional status using geostatistics. The experimental area comprised 1.2 ha, where 27 points were georeferenced and spaced on a regular grid 18 × 18 m. The severity of Yellow Sigatoka, soil fertility and plant nutritional status were evaluated at each point. The spherical model was adjusted for all variables using restricted maximum likelihood. Kriging maps showed the highest infection rate of Sigatoka occurred in high areas of the field which had the highest concentration of sand, while the lowest disease was found in lower areas with lower silt, organic matter, total exchangeable bases, effective cation exchange capacity, base saturation, Ca and Mg in soil, and foliar sulfur (S). These results may help farmers manage Yellow Sigatoka disease more effectively, with balanced fertilization and reduced fungicide application. This practice minimizes the environmental impact and cost of production while contributing to production sustainability.

4‐Phenylphenalenones as a template for new photodynamic compounds against Mycosphaerella fijiensis

Evaluation of 4-phenylphenalenones and structural analogues against the fungal pathogen Mycosphaerella fijiensis (causal agent of black sigatoka disease in bananas) under light-controlled conditions uncovered some key structural features for the design of photodynamic compounds. Structure-activity relationship analysis revealed the importance of a chromophoric aryl-ketone and a steroidomimetic structural motif in the activity of the assayed compounds. The results pointed to 1,2-dihydro-3H-naphtho[2',1':3,4]cyclohepta[1,2-b]furan-3-one, which displayed an activity in the range of propiconazole but with photodynamic behaviour. The present work demonstrates that 1,2-dihydro-3H-naphtho[2',1':3,4]cyclohepta[1,2-b]heterocyclic-3-one derivatives can be used as potential lead compounds for the development of fungicides, relying on a dual mode of action. © 2015 Society of Chemical Industry.

English

The fungus Mycosphaerella fijiensis causes black Sigatoka (BS) disease, a major pathogen in the banana industry worldwide. Numerous molecular and biochemical studies have been done for the M. fijiensis, Musa acuminata interaction, but this is the first study describing the zymographic behavior of β-1,3-glucanase, chitinase and protease in the apoplast and symplast of healthy, BS-infected but asymptomatic and BS diseased banana leaves. In BS-infected tissues, β-1,3-glucanase enzymatic activity was associated with two polypeptides with retention index (R i ) values of 0.43 and 0.56. These were more notable in the apoplast than in the symplast. Chitinase activity in BS-infected tissue in both the apoplast and symplast was mainly associated with a single polypeptide (R i = 0.89). Both β-1,3-glucanase and chitinase activities were apparently more intense in BS-infected leaves than in healthy leaves. Protease activity was associated with two polypeptides (R i = 0.04 and 0.14). In both the apoplast and symplast, the Ri 0.04 polypeptide increased in intensity with disease progression, whereas R i 0.14 polypeptide intensity decreased. Overall protease activity intensity was higher in the symplast. Maximum symplast contamination of the apoplast was 2% as estimated by glucose 6-phosphate dehydrogenase activity, a biochemical marker for symplast. Accumulation of pathogenesis-related enzymatic activities in the apoplast of M. acuminata leaf tissue was caused by hostcontrolled enzyme downloading in response to M. fijiensis infection. Clear differences were identified in the electrophoretic profiles of healthy and diseased banana plants. The results further support a putative role of these enzymes in the extracellular defense repertoire of banana and, more importantly, suggest that M. fijiensis possesses a mechanism for suppression and delay of defense response in M. acuminata . Key words : Black Sigatoka, glucose 6-phosphate dehydrogenase, pathogenesis-related (PR) proteins, polyacrylamide gel electrophoresis (PAGE), retention index (Ri), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

Biological control of banana black Sigatoka disease with Trichoderma

Black Sigatoka disease caused by Mycosphaerella fijiensis is the most severe banana disease worldwide. The pathogen is in an invasive phase in Brazil and is already present in most States of the country. The potential of 29 isolates of Trichoderma spp. was studied for the control of black Sigatoka disease under field conditions. Four isolates were able to significantly reduce disease severity and were further tested in a second field experiment. Isolate 2.047 showed the best results in both field experiments and was selected for fungicide sensitivity tests and mass production. This isolate was identified as Trichoderma atroviride by sequencing fragments of the ITS region of the rDNA and tef-1α of the RNA polymerase. Trichoderma atroviride was as effective as the fungicide Azoxystrobin, which is recommended for controlling black Sigatoka. This biocontrol agent has potential to control the disease and may be scaled-up for field applications on rice-based solid fermentation

Effective control of black Sigatoka disease using a microbial fungicide based on Bacillus subtilis EA-CB0015 culture

Black Sigatoka disease caused by the fungus Mycosphaerella fijiensis Morelet is the most devastating disease of bananas worldwide. Its management is reliant on protectant and systemic fungicides despite their environmental concerns. This study evaluated the effect of a microbial fungicide (MF) based on Bacillus subtilis EA-CB0015 and its metabolites for the control of black Sigatoka disease on banana plants in greenhouse and field conditions. The MF applied at 1.5L/ha and 3.0L/ha provided control of the disease comparable to the protectant fungicide chlorothalonil in greenhouse. In the field, the MF applied in solution with water at 0.15L/ha and 1.5L/ha every 11days during 10weeks reduced black Sigatoka disease severity in 20.2% and 28.1% respectively; reductions comparable to those obtained with the protectant fungicides chlorothalonil (1.5L/ha) and mancozeb (3.8L/ha). The MF incorporated into different programs with systemic fungicides reduced disease level up to 42.9% with no significant differences with the conventional program. To determine which component of the MF is responsible for the activity against M. fijiensis, greenhouse and in vitro tests were set up to evaluate individually the spores, vegetative cells and secondary metabolites of B. subtilis EA-CB0015. All components reduced the severity of the disease and the germination of ascospores. For both trials the activity of the metabolites was higher and comparable to the activity obtained with the MF, indicating that the efficacy of the MF depends mainly on the metabolites and in lesser extent to B. subtilis EA-CB0015 cells.

Sigatoka Disease Complex of Banana in Brazil: Management Practices and Future Directions

Banana (Musa spp.) is one of the world's most important monocotyledonous crops, cultivated in over 100 tropical and subtropical countries. As the world's most consumed fruit, it can represent a source of livelihood in countries of the African continent, where the annual per capita consumption may reach 400 kg. Brazil is responsible for approximately 10% of global production, placing the country behind only India, China, Philippines and Ecuador. Of all the diseases affecting Musa production in Brazil, the largest impact is attributed to M. Fijiensis. Black Sigatoka can depreciate the physical properties of the fruit and cause premature ripening, as well as reduce functional leaf area, the consequence of which is reduced yield, with production losses of up to 100% in susceptible varieties such as M. Acuminate Cavendish Grande Naine (Musa cv. AAA) and Prata (Musa cv. AAB). Black Sigatoka was first reported in 1998 in the Amazon region, with the pathogen subsequently spreading across seven states in the North of the country and Mato Grosso. In 2005, the pathogen was also reported in the states of Mato Grosso do Sul, Sao Paulo, Minas Gerais, Parana and Santa Catarina. Since then, the pathogen has not been officially reported in any new areas, although it remains a threat to the Northeast region of the country. Although M. Fijiensis is regarded as the major constraint to banana production, M. Musicola is more widespread. Observed for the first time in Brazil in 1944 in the Amazon region, the pathogen now occurs in all growing regions, imposing substantial costs to affected growers. Here, losses of up to 50% of production are commonly reported as a result of Yellow Sigatoka. Genetic resistance is absent or partial in the majority of commercial banana cultivars, with the principal measures employed in integrated disease management based on the use of programmed applications of systemic or protectant fungicides.

Antifungal activity of Serratia marcescens CFFSUR-B2 purified chitinolytic enzymes and prodigiosin against Mycosphaerella fijiensis, causal agent of black Sigatoka in banana (Musa spp.)

The ascomycete fungus Mycosphaerella fijiensis causes black Sigatoka disease of banana. Because Serratia marcescens strain CFFSUR-B2 is an effective agent for the biological control of M. fijiensis, it was important to determine the mechanisms by which this bacterium stops or inhibits infection by this phytopathogen. The individual chitinases were effective in reducing germ tube growth to different degrees. We evaluated also the effect of mixtures of purified chitinases (ChiA, ChiB and ChiC) and prodigiosin on the germination and germ tube growth of M. fijiensis ascospores. None of the combinations inhibited ascospore germination. However, a toxic effect similar to that of benzimidazole was observed on ascospore germination by the synergistic action of chitinases and prodigiosin applied in combination. The maximal effect in inhibiting germ tube development observed with a mixture of the chitinases and prodigiosin suggests that these could be used in the effective biocontrol of black Sigatoka disease.

The arbuscular mycorrhiza fungusRhizophagus irregularisMUCL 41833 decreases disease severity of Black Sigatoka on banana c.v. Grande naine, underin vitroculture conditions

Introduction. Mycosphaerella fijiensis, the fungal pathogen causing Black Sigatoka disease, attacks almost all cultivars of bananas and plantains. Currently, the repeated application of fungicides is the most widespread control measure, while the use of bio-control agents remains almost ignored. Here we investigated, under in vitro culture conditions, whether an arbuscular mycorrhizal fungus (AMF – Rhizophagus irregularis MUCL 41833) could reduce the severity of disease caused by M. fijiensis MUCL 47740 on banana. Materials and methods. Prior to their transfer to autotrophic in vitro culture systems and subsequent inoculation by the pathogen, the banana plantlets cultivar Grande Naine (AAA genome Cavendish group) were grown in the extra-radical mycelium network of the AMF, arising from Medicago truncatula plantlets, for fungal root colonization. Results and discussion. At the time of infection with M. fijiensis, the AMF colonization of the banana plantlets was 12%, 56% and 10% for hyphae, arbuscules and spores/vesicles, respectively, and the number of spores produced in the medium was above 200. At day 21 and day 35 following infection by the pathogen, the number of extra-radical spores as well as the abundance of arbuscules in roots, were significantly higher than in the non-infected plantlets. Conversely, the severity index measured in the mycorrhizal plantlets decreased by more than 80% and 60%, respectively, 21 and 35 days after infection by the pathogen. Similarly, the area under disease progress curve, estimated at day 35, was reduced by 59% in the mycorrhizal banana plantlets as compared to the control plantlets. Whatever the treatment (mycorrhizal or non mycorrhizal plantlets in presence/absence of M. fijiensis), no significant differences were observed in plantlet dry weight, pseudostem height and diameter, and leaf area at both observation times. Conclusions. These results emphasize the complex multitrophic interactions between above and below-ground microorganisms mediated via the plant. They further suggest that AMF may decrease, at least at the early stage of infection, M. fijiensis symptoms possibly via the induction of a systemic resistance pathway. The important decrease in symptoms observed in the mycorrhizal banana plantlets suggest that these microorganisms may represent a potentially attractive option to consider in the context of an integrated control of this important disease.

Antifungal activity of fungicides and plant extracts against yellow sigatoka disease causing Mycosphaerella musicola

Mycosphaerella musicola causes yellow sigatoka disease in banana plantations, and affects overall yield and quality of the fruit. Synthetic fungicides are used to control disease. An integrated approach by using plant based extracts and synthetic fungicides can control the disease efficiently by reducing the usage of fungicides. In vitro studies were carried out to test methanolic extracts of ten plants belonging to seven different families having previous reports on antimicrobial activity against Mycosphaerella musicola, methanolic extracts of two plants showed significant antifungal activity as well as significant inhibition of spore germination in spore germination inhibition assay. All eight fungicides exhibited inhibitory action on M. musicola in poison food technique, where as MIC range of each fungicide varied significantly. The results revealed that integrated disease management by using efficient plant extracts and effective fungicides can control the disease and the pathogen in fields efficiently.

Behavior of plantain clones Maricongo and FHIA 21 under the presence of black Sigatoka at the humid uplands of Puerto Rico

Agronomic characteristics and black Sigatoka disease severity of plantain clones Maricongo and FHIA 21 were evaluated in the humid upland region in Corozal, Puerto Rico. A 2x2 factorial experimental design (two clones and two management practices for black Sigatoka) with four replications was used. The management of black Sigatoka consisted of removing (deleafing) the infected leaves starting five months after planting followed by rotational applications of systemic and contact fungicides at 15 days intervals. This treatment was compared with a control treatment where no practices were performed for controlling Sigatoka. The FHIA 21 clone showed higher tolerance to black Sigatoka than the Maricongo clone. The management of black Sigatoka treatment significantly increased the average bunch and fruit weights for both plantain clones. On the other hand, results showed a high incidence (27.5%) of FHIA 21 clone plants with banana streak virus (BSV) symptoms compared with 3.5% in Maricongo. Commercial cultivation of FHIA 21 in Puerto Rico is not recommended at this moment, but further evaluation of the clone in different zones is recommended.

Phenolic profiling in the pulp and peel of nine plantain cultivars (Musa sp.)

The present study investigated the phenolic profiles of the pulp and peel of nine plantain cultivars and compared them to those of two dessert bananas of commercial interest (Grand Nain and Gros Michel), alongside a newly created hybrid, resistant to black sigatoka disease (F568). Identification and quantification of phenolic compounds were performed by means of HPLC–ESI-HR-MS and HPLC-DAD. Hydroxycinnamic acids, particularly ferulic acid-hexoside with 4.4–85.1μg/g of dry weight, dominated in the plantain pulp and showed a large diversity among cultivars. Flavonol glycosides were predominant in plantain peels, rutin (242.2–618.7μg/g of dry weight) being the most abundant. A principal component analysis on the whole data revealed that the phenolic profiles of the hybrid, the dessert bananas and the pure plantains differed from each other. Plantain pulps and peels appeared as good sources of phenolics, which could be involved in the health benefits associated with their current applications.

Singlet molecular oxygen generation by light-activated DHN-melanin of the fungal pathogen Mycosphaerella fijiensis in black Sigatoka disease of bananas.

In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis.

Effect of different levels of Sigatoka disease severity on banana pulp colour and early ripening

Bananas are usually harvested at a green preclimacteric stage prior to sale. The preclimacteric phase is called green life (GL), which is defined as the number of days between harvesting and initiation of the natural ripening process. Sigatoka disease (SD) has previously been shown to influence the postharvest behaviour of banana fruit. This work was set out to determine whether there is a relationship between the level of SD severity and the extent of the effects on banana quality as characterized by several pomological traits, especially pulp colour. In an experiment conducted with fruits harvested at a constant physiological age, our results showed that SD had a major effect on the percentage of fruit ripening in the field and on fruit weight, but not on fruit diameter. We showed too that pulp colour was greatly affected by SD; when severity increased, pulp colour parameters were modified – L* (lightness) decreased, a* (axis red to green) and b* (axis yellow to blue) increased, giving a more greyish pulp colour, with less green and more yellow and red. These results may enable the development of a method for controlling fruit quality, by measuring pulp colour in the field, in order to reduce post-harvest losses.

Genetic diversity of Mycosphaerella fijiensis in Brazil analyzed using an ERIC-PCR marker

The Enterobacterial repetitive intergenic consensus (ERIC) marker was used to analyze the genetic variability of Mycosphaerella fijiensis, the causative agent of Black Sigatoka disease in banana plants. A total of 123 isolates were used, which were divided into populations based on their original hosts and collection sites in Brazil. A total of 9 loci were amplified, 77.8% of which were found to be polymorphic. The genetic diversity found in the population was 0.20. Analysis of molecular variance (AMOVA) demonstrated that the highest level of genetic variation is within populations. Cluster analysis revealed three main groups in Brazil, with no correlation between geographic and genetic distance.

Mycosphaerella musicola Identified as the Only Pathogen of the Sigatoka Disease Complex Present in Minas Gerais State, Brazil.

A thorough assessment of the distribution of Mycosphaerella spp. associated with banana in Minas Gerais State, Brazil, was conducted after Mycosphaerella fijiensis was first reported to occur in this region in 2005. From 2009 to 2011, 80 fields located in 20 municipalities including the same fields where the disease was first reported were sampled. A total of 800 samples of leaf tissue with symptoms similar to those of yellow or black Sigatoka diseases were examined, and 239 isolates were obtained. The identification of the fungi was based on morphological characters combined with DNA sequences obtained after amplification with species-specific primers and phylogeny inferred from the internal transcribed spacer region of Mycosphaerella strains from banana. All 239 isolates were identified as Mycosphaerella musicola. The absence of M. fijiensis in the samples may have been due to misidentification of M. fijiensis or the displacement of M. fijiensis by M. musicola. It is now apparent that yellow Sigatoka caused by M. musicola is the prevailing leaf spot disease of bananas in Minas Gerais State and that regulatory/legislative control measures need to be revised based on our findings.

Impact of the extension of black leaf streak disease on banana susceptibility to post-harvest diseases

Impact of the extension of black leaf streak disease on banana susceptibility to post-harvest diseases. Abstract - Introduction. The susceptibility of banana fruit to crown rot and anthracnose, the two main banana post-harvest diseases, is influenced by many pre-harvest abiotic factors. Mycosphaerella leaf spot diseases (MLSD) of bananas are biotic pre-harvest factors, which have an influence on fruit physiology. The fruit's susceptibility to post-harvest diseases may also be influenced by foliar diseases caused by M. fijiensis, responsible for black leaf streak disease (BLSD), and M. musicola, which causes sigatoka disease (SD). The aim of our study was to determine the influence of these biotic pre-harvest factors on banana fruit's susceptibility to crown rot and anthracnose. Materials and methods. A disease severity gradient was established in two experimental fields (Cameroon for BLSD and Guadeloupe for SD) where, at the flowering stage, six different levels of MLSD severity were selected. Fruit susceptibility was determined through necrotic surface assessments after artificial inoculation by Colletotrichum musae on the 3rd hand of harvested bunches. Results and discussion. BLSD significantly influenced banana sensitivity to crown rot (P 0.05) on banana susceptibility to either post-harvest disease. These results are discussed with emphasis on the influence of variations in the source-sink ratio on fruit physiology. The influence of BLSD on crown rot disease suggests the need to take into account the management of these foliar diseases for an alternative control method of post-harvest diseases through integrated pest management programs. Cameroon / Guadeloupe / Musa / fruits / Mycosphaerella fijiensis / Mycosphaerella musicola / black sigatoka / black leaf streak disease / anthracnoses / crown rots Impact de l'extension de la maladie des raies noires sur la sensibilite des bananes aux maladies post-recolte.

Necrotic leaf removal, a key component of integrated management ofMycospaerellaleaf spot diseases to improve the quality of banana: the case of Sigatoka disease

Introduction. Bananas are harvested at the green preclimacteric stage prior to sale. The time between harvest and the initiation of the natural ripening process is called green life. Black Leaf Streak Disease and Sigatoka Disease are the main foliar diseases affecting banana production. Sigatoka Disease (SD) is due to Mycosphaerella musicola , which frequently causes early ripening in commercial banana plantations, considered as an important source of damage. Our work aimed at determining the effectiveness of the removal of necrotic leaves, one month before harvest, on recovering banana quality arising from SD-infested plants. Materials and methods. Banana plants (totaling 80) at the flowering stage were selected in an experimental plot. These plants were divided into two groups of SD infestation levels: level 1 (Severity Index at flowering 25%). We divided each group into two treatments: a treatment with no necrotic leaf removal and a treatment with necrotic leaf removal. Fruits were harvested at the same physiological age, at 900 degree-days. Fruit quality was characterized by weight, diameter, % of ripe fruit in the field and fruit green life. Results. Our results showed that the removal of necrotic leaves causes a reduction in size parameters but leads to a strong reduction in SD effects on the fruit maturity, thereby preventing premature ripening. Banana plants whose necrotic leaves were removed produced fruit with a very long green life. Discussion. Removal of necrotic leaves allows thwarting the negative effect of SD on fruit physiology. This shows that the presence of necrosis during the last month of fruit growth is responsible for this fruit physiological modification characterized by early ripening. Conclusion. Removal of necrotic leaves one month before the date of harvest may be a technique that can limit production losses when the infestation level by SD is high. (Resume d'auteur)

On-Farm Evaluation of Deleafing Frequency on the Severity of Black Sigatoka Disease (Mycosphaerella fijiensis Morelet) and Yield of Banana (Musa spp)

On-Farm Evaluation of Deleafing Frequency on the Severity of Black Sigatoka Disease (Mycosphaerella fijiensis Morelet) and Yield of Banana (Musa spp)