Black Sigatoka Research Articles

Role of Bacillus tequilensis EA-CB0015 cells and lipopeptides in the biological control of black Sigatoka disease

Black Sigatoka disease is a devastating fungal pathogen that affects banana crops worldwide and is caused by the ascomycete fungus Pseudocercospora fijiensis. In an effort to mitigate the environmental impacts of chemical fungicides, microbial biological control agents (MBCA) have been developed. However, a comprehensive understanding of the modes of action of these products are needed to enhance their efficacy under field conditions. Consequently, the functional role of different components of a Bacillus tequilensis EA-CB0015-based product was studied to understand their role in conferring protection to banana plants against the infection of P. fijiensis. Under this perspective, we evaluated the effect of B. tequilensis EA-CB0015 lipopetides on the severity of black Sigatoka disease, as well as the ability of the bacterial cells to colonize and produce lipopeptides on the leaf surface of banana plants (Musa AAA cv. Williams). Our work provides evidence that lipopetides significantly reduce the disease severity and that the bacterial cells colonize the leaf surface of banana plants inoculated with P. fijiensis during the first 48 h of incubation. Furthermore, we were able to detect an increased production of surfactins during colonization using mass spectrometry analysis. Altogether, our results suggest that the biological control strategies implemented by the MBCA product against P. fijiensis involves a direct interaction via antibiosis, as well as an indirect interaction via competition of nutrients and space.

Is the Covid‐19 Pandemic a Game Changer in GMO Regulation?

SummaryThe Covid‐19 pandemic has the potential to act as a much‐needed trigger for changes to the European Union regulations around genetically modified organisms (GMOs). There are two main reasons for this potential development. Firstly, the majority of vaccines under development would fall under Directive 2001/18 on the release of GMOs into the environment. The European Parliament and Council agreed that, in Recital 17 of Regulation 2020/1043, the current approval procedure for GMOs is not well‐suited to improving public health. This was driven in particular by the need for vaccine approval in the context of the Covid‐19 pandemic; and a more appropriate approval procedure would be applied. Secondly, several studies have shown that the Covid‐19 crisis reduces the purchasing power of households and increases their vulnerability in the case of food shortages; and consequent increases in food prices further exacerbate the nutritional problems of vulnerable groups. Modern plant breeding has the potential to provide less expensive solutions to support vulnerable groups. As the Covid‐19 crisis drains government budgets, views around GMOs in the EU may change in the light of positive experiences from the approval of Covid‐19 vaccines.

Pseudocercospora and allied genera associated with leaf spots of banana (Musa spp.).

The Sigatoka leaf spot complex on Musa spp. includes three major pathogens: Pseudocercospora, namely P. musae (Sigatoka leaf spot or yellow Sigatoka), P. eumusae (eumusae leaf spot disease), and P. fijiensis (black leaf streak disease or black Sigatoka). However, more than 30 species of Mycosphaerellaceae have been associated with Sigatoka leaf spots of banana, and previous reports of P. musae and P. eumusae need to be re-evaluated in light of recently described species. The aim of the present study was thus to investigate a global set of 228 isolates of P. musae, P. eumusae and close relatives on banana using multigene DNA sequence data [internal transcribed spacer regions with intervening 5.8S nrRNA gene (ITS), RNA polymerase II second largest subunit gene (rpb2), translation elongation factor 1-alpha gene (tef1), beta-tubulin gene (tub2), and the actin gene (act)] to confirm if these isolates represent P. musae, or a closely allied species. Based on these data one new species is described, namely P. pseudomusae, which is associated with leaf spot symptoms resembling those of P. musae on Musa in Indonesia. Furthermore, P. eumusae, P. musae and P. fijiensis are shown to be well defined taxa, with some isolates also representing P. longispora. Other genera encountered in the dataset are species of Zasmidium (Taiwan leaf speckle), Metulocladosporiella (Cladosporium leaf speckle) and Scolecobasidium leaf speckle. Citation: Crous P, Carlier J, Roussel V, Groenewald JZ (2020). Pseudocercospora and allied genera associated with leaf spots of banana (Musa spp.). Fungal Systematics and Evolution 7: 1-19. doi: 10.3114/fuse.2021.07.01.

English

Pests and diseases greatly contribute to the decline in banana yields, food and income insecurity in the Great Lakes region of Africa. Understanding people’s role in pest and disease spread at landscape level is crucial for effective pest and disease management. To determine this, focus group discussions (FGDs) targeting 10 experienced farmers (50% female and 50% male) were conducted in 27 villages along four banana trade routes in western Burundi and eastern DR Congo. FGDs determined the presence and risk of spread of key banana pests and diseases via the movement of banana bunches, planting material and other products, labourers, traders and farm tools. Black leaf streak (BLS), Fusarium wilt and banana bunchy top disease (BBTD) were reported to have been in the landscape for over 40 years while Xanthomonas wilt (XW) was a more recent introduction (1-7 years). BBTD, XW and weevils were the most prevalent constraints. BBTD was observed at previously unsuitable high-altitude zones, which should be a cause of concern, especially with the current risk of climate change. Climate change, and linked temperature increases, could also worsen the prevalence of XW, weevils, nematodes and BLS. Movement of farming tools by labourers and traders, of planting material/suckers and banana bunches emerged as the most common human practices potentially responsible for the spread and/or build-up of banana pests/diseases. Strengthening farmer’s knowledge and institutional capacities of actors on these different modes of disease spread in banana value chains in the region is recommended. Key words: Black leaf streak, bunchy top disease, Fusarium wilt, nematodes, weevils, Xanthomonas wilt. &nbsp

Climate and the Global Spread and Impact of Bananas’ Black Leaf Sigatoka Disease

While Black Sigatoka Leaf Disease (Mycosphaerella fijiensis) has arguably been the most important pathogen affecting the banana industry over the past 50 years, there are no quantitative estimates of what risk factors determine its spread across the globe, nor how its spread has affected banana producing countries. This study empirically models the disease spread across and its impact within countries using historical spread timelines, biophysical models, local climate data, and country level agricultural data. To model the global spread a empirical hazard model is employed. The results show that the most important factor affecting first time infection of a country is the extent of their agricultural imports, having increased first time disease incidence by 69% points. In contrast, long distance dispersal due to climatic factors only raised this probability by 0.8% points. The impact of disease diffusion within countries once they are infected is modelled using a panel regression estimator. Findings indicate that under the right climate conditions the impact of Black Sigatoka Leaf Disease can be substantial, currently resulting in an average 3% reduction in global annual production, i.e., a loss of yearly revenue of about USD 1.6 billion.

Evaluation of the development of Mycosphaerella Fijiensis Morelet, collected in the centre and linder in planting of Musa sp. AAA

The study evaluated the disinfection medium to obtain in vitro mycelia of M. fijiensis, in samples of banana leaves (Musa sp. AAA) collected in the center (BI) and the border (AI) of the banana, of the Hacienda El Playón, Pasaje canton, El Oro province. In order to unload the ascospores in the laboratory, cuttings of 7 x 7 cm leaves with SN symptoms were made in plastic containers with a capacity of 500 mL and incubated for 72 hours. The samples of the fragments were placed in sterile distilled water on sterile filter paper to remove water residues and with the help of a scalpel, they were sown in potato-dextrose-agar (PDA) culture medium in Petri dishes, sealed with paper. parafilm, then they were placed to incubate for 7, 14 and 21 dds, at an average temperature of 27 ° C ± 2 ° C. The experimental design was completely randomized, with six treatments and three repetitions, each consisting of 30 Petri dishes. Statistical differences were presented due to the effect of the treatments (P <0.01) for the germination and growth of the mycelia. Treatments T5L and T6C (disinfection with sterile distilled water + 1 minute immersion) showed between 93 and 100% germination and mycelia growth at 21 dds between 23 and 24 mm to guarantee an axenic culture.

First Draft Genome Sequence Resource of a Strain of Pseudocercospora fijiensis Isolated in North America.

Black Sigatoka disease, caused by the fungus Pseudocercospora fijiensis, is one of the most devastating diseases of banana around the world. Fungicide applications are the primary tool used to manage black Sigatoka, but fungicide resistance in P. fijiensis, as in other fungal pathogens, is one of the major limitations in the efficient management and prevention of this disease. In the current study, we present the draft genome of P. fijiensis strain IIL-20, the first genomic sequence published from a strain of this fungus isolated in North America. Bioinformatic analysis showed putative genes involved in fungus virulence and fungicide resistance. These findings may lead us to a better understanding of the molecular pathogenesis of this fungal pathogen and also to the discovery of the mechanisms conferring fungicide resistance.

Agro-morphological diversity of plantain accessions from different part of the world

The objective of this study was to characterize the agro-morphological diversity of plantain accessions. 18 quantitative variables and 20 qualitative variables were measured. The results of the analysis of the qualitative variables revealed important traits such as black Sigatoka resistance of FHIA 21, Pita 3, M53, Calculta 4 and Banskii accessions and the firm fruit texture of Galeo, Kokor, French sombre and Corne 1 accessions. A Principal Component Analysis (PCA) performed with the quantitative variables separated the 9 accessions into 4 groups with particular and important characteristics which can be exploited differently in genetic improvement programme according to the breeding objective. From these results, it appears clearly that the objective is achieved.Keywords: Sigatoka, qualitative variables, quantitative variables, genetic improvement.

Essential Tea Tree Oil As a Tool to Combat Black Sigatoka in Banana

Black Sigatoka disease, caused by Mycosphaerella fijiensis, is considered the most damaging and costly disease of commercial banana and plantain and is mainly controlled by intensive sprays of synthetic fungicides. Essential tea tree oil derived from Melaleuca alternifolia plant was found to be effective against a wide range of plant pathogenic fungi including black Sigatoka in conventional production systems and was as effective as synthetic fungicides such as tridemorph, difenoconazole, trifloxystrobin and azoxystrobin. This paper provides evidence that tea tree oil offers an attractive alternative for controlling black Sigatoka in banana plantations.

Early detection of black Sigatoka in banana leaves using hyperspectral images.

PremiseBlack Sigatoka is one of the most severe banana (Musa spp.) diseases worldwide, but no methods for the rapid early detection of this disease have been reported. This paper assesses the use of hyperspectral images for the development of a partial‐least‐squares penalized‐logistic‐regression (PLS–PLR) model and a hyperspectral biplot (HS biplot) as a visual tool for detecting the early stages of black Sigatoka disease.MethodsYoung (three‐month‐old) banana plants were inoculated with a conidia suspension of the black Sigatoka fungus (Pseudocercospora fijiensis). Selected infected and control plants were evaluated using a hyperspectral imaging system at wavelengths in the range of 386–1019 nm. PLS–PLR models were run on the hyperspectral data set. The prediction power was assessed using leave‐one‐out cross‐validation as well as external validation.ResultsThe PLS–PLR model was able to predict the presence of the disease with a 98% accuracy. The wavelengths with the highest contribution to the classification ranged from 577 to 651 nm and from 700 to 1019 nm.DiscussionPLS–PLR and HS biplot effectively estimated the presence of black Sigatoka disease at the early stages and can be used to graphically represent the relationship between groups of leaves and both visible and near‐infrared wavelengths.

Performance of Plantain (Musa Paradisiaca L) Fruit Yield and Quality under Different Planting Densities and Water Application

The performance of plantain fruit yield and quality under different planting densities under an influence of irrigation system was investigated at International Institute of Tropical Agriculture, Ibadan, Oyo State, Nigeria. Experiments were set up as a split plot fitted into randomized complete block design (RCBD) with three replications. Main plots are irrigation system while sub-plots are plant densities. Treatments included four plant densities (1 x 2, 2 x 2, 2 x 3, and 3 x 3 m), two irrigation systems and their combination where irrigation system was the main plot and plant density the sub-plot. Over 2,000 agbagba suckers were pared and hot–water treated, and planted during the first week of the experiment. Manure was applied at the rate of three spades full per plant for nutrient supplement; and mulching was done. Weeds were manually controlled as at when due. Plantain diseases like yellow sigatoka and black sigatoka were also controlled manually by de-leafing infected leaves to prevent disease spread. Data were collected and analyzed using ANOVA. Duncan multiple range test (DMRT) was used for mean separation at 5% level of significance. The results of ANOVA showed that there were significant effects (P < 0.05) due to irrigation application for all measured parameters whereas effects due to plant densities were significant for only these parameters; number of suckers (NOS), sucker height (SUHT), number of leaves on sucker (NLSC), bunch weight (BWT), number of hand (NHND), total number of finger (TFNG) and number of sucker at flowering (NSCK). Therefore, it can be concluded that plant spacing, and regular water supply plays a significant role in obtaining good yield in plantain production

Boragen, Dole seek banana fungicide

The boron chemical discovery firm Boragen will collaborate with Dole Food Co. to find fungicides to combat the banana fungal disease Black Sigatoka. The prevalent and damaging disease is caused by ...

Application of phosphate fertilization on banana hybrid ‘FHIA 18’and its impact on production performance

FHIA 18 is a hybrid banana that could replace cultivar Prata, which is highly affected by Black Sigatoka and Panama disease. Still, there is a paucity of literature on FHIA 18 nutrient requirements, especially phosphorus. Nevertheless, we aimed to estimate the best phosphorus levels and its effect on the productive characteristics of FHIA 18 during three crop cycles in the city of São Manuel, state of São Paulo. Triple superphosphate has been given at recommended rates of 0, 20, 30, 40, 50 and 60 kg P2O5 ha-1 year-1 for three crop cycles that occurred in January 2014 (first cycle), August 2014 (second cycle) and June 2015 (third cycle). Results indicated that maximum fruit number per bunch was achieved at 30 and 26 kg P2O5 ha-1, corresponding to second and third cycle, respectively. Moreover, there was an increase in bunch mass, fruit mass, number of hands per bunch, mass and length of the fruit in the second hand, when P2O5 reached its maximum values from 20 to 34 kg P2O5 ha-1 year-1, but fruits diameter decreased. Results also showed that FHIA 18 required lower level of P2O5 to achieve maximum yield than the recommended doses for other banana cultivars in the state of São Paulo. Therefore, this current study recommends a rate of 22 kg P2O5 ha-1 year-1 for FHIA 18 to reach its maximum production.

Impact of arbuscular mycorrhizal fungus (<i>Rhizophagus irregularis</i>) on disease symptoms caused by the ascomycete fungus (<i>Mycosphaerella fijiensis M.</i>) in Black Sigatoka-resistant banana plantain

Banana (Musa spp.) is grown throughout the tropical and subtropical areas. The Black Sigatoka, however, represents a major threat to world production. This study evaluates the effect of the arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis MUCL 41833 on four plantain cultivars with different resistance against Mycosphaerella fijiensis. The mycorrhized banana plantlets of four cultivars were grown under greenhouse and the effect of AMF on micropropagated banana plantlets was evaluated. After 35 days, the height and the diameter of the pseudostem, then the leaf area were measured. The significant effect of the cultivar on the height of the pseudostem and the leaf area and significant effect of M. fijiensis on the diameter of the pseudostem, the height of the pseudostem and the leaf area were obtained. Plants infected with M. fijiensis show more symptoms of the disease than healthy plants. Symptoms were delayed in bananas inoculated with AMF compared to bananas not inoculated with AMF. The disease progressed more rapidly in cultivars Bâtard and C292 than in cultivars CRBP39 and F568. These results suggest that AMF may decrease symptoms of Sigatoka, at the early stage of infection with M. fijiensis. AMF may be a promising tool for the pre-adaptation of micropropagated banana plantlets.
 Keywords: Plantain, Rhizophagus irregularis, arbuscular mycorrhiza fungi, Mycosphaerella fijiensis, disease control method.

Curative and Suppressive Activities of Essential Tea Tree Oil against Fungal Plant Pathogens

Timorex Gold based on the essential tea tree oil (TTO) derived from the Australian tea tree oil (Melaleuca alternifolia) plant has demonstrated high efficacy and a strong curative activity against black Sigatoka in banana and controlled it in stages 1, 2, 3, and 4 of disease development. Transmission electron microscope (TEM) examination of infected leaf sections treated with Timorex Gold revealed disruption of the fungal cell membrane and destruction of the fungal cell wall in disease development stages 4 and 5. Mineral oil and the fungicide difenoconazole, when applied alone, had no curative effect and did not disrupt the fungal cell wall or membrane, similar to the untreated control tissue. A single spray of Timorex Gold effectively controlled and suppressed powdery mildew in cucumber by causing the disappearance of 99% of established colonies recorded 1 or 2 days after the application and was effective for up to 8 days after application. Scanning electron microscope (SEM) examination of infected and Timorex Gold-treated leaves indicated strong shrinkage and disruption of fungal hyphae and conidial cells. The curative and suppressive modes of action of the Timorex Gold may explain its success in controlling both diseases.

Detection of foliar diseases using image processing techniques

ABSTRACT This paper presents the development of a methodology to detect the percentage of affected area of Phytophthora infestans disease in tomato plants, using digital image processing techniques to extract the regions of interest with color analysis, where the YIQ and TSL models for the detection of the disease. The method consists of solving one of the most common problems in images that is segmentation, in this case the background and the disease with the Plant Village database, which was captured under uncontrolled lighting conditions. In the experiments conducted, it is observed that our method achieved a performance of 98.60% for the detection of healthy pixels and 98.17% in detection of sick pixels. This process was subjected to comparison against other alternatives of the state of the art like K-means with HSV and LAB, showing a referred error regarding the leaf size of 4.32 ± 5.44% in the detection of the disease and a computational time of 0.03 ± 0.01 [s] in comparison with the other procedures, in addition, this methodology was implemented to detect the foliar diseases black Sigatoka and yellow Sigatoka in banana leaves obtaining satisfactory results.

English

Plantain prices in sub-Saharan markets are very high due to the fact that the supply does not cover the large demand. The main constraint of plantain cultivation is the seedlings unavailability in quantity and quality, which is essential to boost the creation of new plantations. The PIF technique could solve this problem if its substrate of production is amended with natural products for quality enhancement. This study aims to assess clam shells and Tithonia diversifolia effects on the growth of PIF plantain seedlings and their sensitivity to Mycosphaerella fijiensis. Plantain PIF seedlings were grown in an amended substrate. The treatment influences the seedlings germination rate, number of shoots, height, diameter, area of leaves and favours a less sensitivity to M. fijiensis compared to the controls. The presence of clam shells and T. diversifolia in the treatment especially enhanced the (1) vegetative growth and (2) less sensitivity as well as accumulation of proteins and polyphenols respectively. This combination shows a synergic action with dual role both as a biofertilizer and as a biopesticide. This work valorises the use of by-fishing products and bad herbs that are environmentally benign and affordable to poor smallholders’ farmers, leading to a sustainable and responsible agriculture, as well as poor peasants’ empowerment. Key words: Plantain (Musa spp.), PIF seedlings, Tithonia diversifolia, clam shells, biofertilizer, biopesticide, Mycosphaerella fijiensis.   &nbsp

Differential regulation of jasmonic acid pathways in resistant (Calcutta 4) and susceptible (Williams) banana genotypes during the interaction with Pseudocercospora fijiensis

AbstractOne of the main biosecurity problems facing banana crops is black Sigatoka disease, caused by the fungus Pseudocercospora fijiensis. Disease control is achieved mainly by chemical sprays and generates more than 50% of the costs of production, with a trend to increase due to the rapid resistance that the fungus acquires to the main fungicide molecules. Thus, it is very important to acquire information on the molecular mechanisms of the plant–pathogen interactions in this pathosystem as a way to help design future control strategies. Hormonal plant responses of banana genotypes susceptible and resistant to P. fijiensis were identified and analysed in this work by transcriptomic (RNA‐Seq and RT‐qPCR) and metabolomic studies (ultraperformance liquid chromatography‐mass spectroscopy). Differentially expressed genes related to signal transduction and biosynthesis pathways of jasmonic acid (JA) and ethylene (ET) were identified in the resistant variety Calcutta 4 during the early stage of interaction with P. fijiensis. Metabolomic analysis corroborated the induction of metabolites related to JA and ET pathways during the first 72 hr post‐inoculation. Observed results are evidence that signalling via JA/ET could be key in the activation of defence response signals in the resistant variety Calcutta 4.

Antifungal protein determination for submerged cultures of the medicinal mushroom <i>Ganoderma lucidum</i> (Ganodermataceae) with activity over the phytopathogen fungus Mycosphaerella fijiensis (Mycosphaerellaceae)

Banana is one of the most important edible crops in the world, however, it’s attacked by different pathogens, one of the most prominent of these is the fungus Mycosphaerella fijiensis, causal agent of Black Sigatoka. The environmental and economic issues related to the pesticides used for its control have encouraged the search for cleaner alternative biomolecules. Previous studies were made by the Biotechnology group from the Universidad de Antioquia searching for a biological alternative for the control of M. fijiensis; in these the antifungal capacity of the fungus Ganoderma lucidum was determined as an antagonist and then as a source of protein extracts with inhibitory activity in vitro and in greenhouse plants; these findings were the foundation of this work, which focuses in the study of the enzymatic capacity of the proteins present in the protein extracts, due to their potential ability to degrade different compounds, including polysaccharides, lipids, peptides and nucleic acids, constituents of essential parts of a living cell; therefore these extracts can act as possible antifungal agents. In this study, protein extracts of G. lucidum obtained from bioreactor cultures (BIOFLO 110 ®) were characterized in terms of their deoxyribonuclease, ribonuclease, protease, glucanase and chitinase enzymatic activities. The extracts were also fractionated and each fraction obtained was evaluated for its inhibitory capacity against the phytopathogen fungus M. fijiensis, and through mass spectrometry analysis the presence of different enzymes with antifungal potential was confirmed.

Yield and nutritional evaluation of the banana hybrid ‘FHIA-18’ as influenced by phosphate fertilization

The ‘FHIA-18’ hybrid banana is an alternative for producers as it is resistant to Black Sigatoka and Panama disease. However, few studies report the nutritional requirement of this hybrid, especially phosphorus. It is known that the efficiency of phosphorus use can be improved, reducing the need for application, depending on the genotype cultivated. Therefore, this study aimed to evaluate the yield and mineral nutrition of ‘FHIA-18’ hybrid banana on phosphate fertilization. A banana orchard with the cultivar ‘FHIA-18’ was conducted on a Typical Red Latosol. Then, triple superphosphate fertilizer was applied on plants at 0, 20, 30, 40, 50, and 60 kg ha−1 year−1, over three productive seasons. At the time of flowering the macro and micronutrient contents of the leaves were evaluated. Subsequently, the nutrient contents of the fruits were evaluated. For this, fruit pulp samples from the third and fourth hands were collected. In addition, yield was estimated considering cluster mass and plant density. The following dose 36 kg ha−1 of P2O5 year−1 increased the content of phosphorus in the leaf, despite that banana hybrid cultivar FHIA 18 demanded 50% of the recommended fertilizer to achieve its maximum yield (29.4 t ha−1 year−1). Phosphate fertilization promoted significant changes in P, Ca, Cu, and Zn contents of leaves and fruits. Therefore, it is concluded that the mineral nutrition of banana ‘FHIA-18’ is affected by phosphate fertilization, as well as requiring less P than recommended to achieve higher yield.