Fusarium oxysporum Schlecht. is a cosmopolitan species complex that consists of both pathogenic and non-pathogenic members. The pathogenic members are subdivided into formae speciales, based on virulence to specific host species. More than 150 formae speciales have been described, of which F. oxysporum f.sp. cubense (E.F.Smith) Snyder and Hansen (Foc), causal agent of Fusarium wilt of banana, is regarded as one of the economically most important and destructive. According to phenotypic and genotypic markers, Foc has been classified into three races and 24 vegetative compatibility groups, and can be divided into a number of clonal lineages that roughly correspond with VCG groupings. In this thesis, we investigated the evolutionary relationships among VCGs using multi-gene sequencing and MAT genotyping. A PCR-RFLP fingerprint discriminating the Foc lineages and a PCR primer that identified Foc ‘subtropical’ race 4 isolates, was developed. Nine microsatellite markers (SSRs) were applied to a global population of Foc in order to investigate diversity not always detectable using sequencing data. Phylogenetic analysis of isolates representing Foc, various other formae speciales of F. oxysporum and non-pathogenic F. oxysporum of the genes encoding the translation elongation factor-1á (TEF), the mitochondrial small subunit (MtSSU), ribosomal RNA (rRNA), the repeated region encoded on the mitochondrion (MtR) and the intergenic spacer (IGS) gene regions separated these isolates into four clades, two of which included Foc. Within these two clades, Foc separated into six lineages that broadly corresponded to VCGs, while the non-pathogenic isolates of F. oxysporum grouped together in only one of the two clades, with an unknown Foc VCG isolate. The mating type of all isolates was determined and crosses were attempted between isolates harbouring MAT-1 and MAT-2 genes, without success. Cultural, morphological and pathogenic variation among isolates of Foc was unable to identify lineages as species. The separation of Foc isolates into two clades suggested that the banana pathogen evolved during two unrelated events. Factors such as horizontal gene transfer, however, might also have played a part in the pathogen’s evolution, as was evident from the divergent placement of some VCGs and lineages within the phylogenetic trees constructed. The inclusion of other formae speciales of F. oxysporum and non-pathogenic F. oxysporum isolates illustrated the great diversity that exists within the F. oxysporum complex. The inclusion of the Foc isolate of an unknown VCG suggests that the genetic diversity of Foc might be far greater than what is known and what was revealed in this study. The opposite mating types found in the respective lineages indicate a sexual origin for the Fusarium wilt fungus that could account for its polyphyletic nature. Within South Africa, Foc ‘subtropical’ race 4 is regarded the most important constrain to banana production. Conventional control practices for Fusarium wilt of banana are ineffective, and disease management relies heavily on the use of clean planting material and the early detection and isolation of the pathogen, in order to restrict spread to unaffected areas. Identification of Foc typically involves vegetative compatibility assays and pathogenicity testing using a set of differential host cultivars. The development of a PCR-based method for the rapid and accurate identification of Foc ‘subtropical’ race 4 will, therefore, be of great importance. The lack of morphological variation between lineages of Foc, and between pathogenic and non-pathogenic members, as well as the unreliability in race identification in Foc, makes the use of molecular tools a viable alternative. Following DNA isolation, PCR and sequencing of the MtR, the DNA sequence data revealed an 8-bp insertion that was subsequently targeted for the design of a Foc ‘subtropical’ race 4-specific primer. Isolates were positively identified as Foc ‘subtropical’ race 4 with the amplification of an 800-pb fragment. The development of the Foc ‘subtropical’ race 4 primer will aid in rapid and accurate detection of the Fusarium wilt pathogen of banana. The population structure defined according to SSR data of a global population of 239 Foc isolates resembled the structure defined according to multi-gene phylogeny, with some exceptions. Measures of gene and genotypic diversity unequivocally supported the opinion that Asia is the centre of origin of Foc. The presence of unique genotypes in all geographically-defined Foc populations could potentially indicate their evolution outside the centre of origin, although this is highly unlikely. The absence of certain genotypes from the Asian population was either due to insufficient and selective sampling, or it demonstrated the effects of clonal selection in combination with adaptation to the forces of geographic isolation and environmental changes over time. The worldwide collection of Foc mostly consisted of six over represented genotypes, thereby providing support for a clonal genetic structure. It was, however, not possible to reject the hypothesis of a recombining population for the populations representing isolates of Lineage V. The implication of recombination within some Foc lineages may be due to unobserved sexual reproduction in nature or the historical association with a sexual ancestor. When one considers diversity within and among genotypes, a specific genotype was mostly associated with only one or two Foc VCGs, therefore indicating that vegetative compatibility determination, in combination with phylogenetic analyses, is a powerful tool for characterizing isolates causing Fusarium wilt of banana. Results from this study, in combination with the multi-gene phylogeny, clearly indicated the presence of unrelated lineages that most probably represent cryptic species. Copyright 2008, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Fourie, G 2008, Evolutionary biology of Fusarium oxysporum f.s.p. cubense, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11192008-094622/> E1216/gm / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Fusarium oxysporum f.sp. cubense Schlecht (Foc), causal agent of Fusarium wilt of banana (Panama disease), is considered to be one of the most serious threats to banana production in the world. There is no effective control measure for Fusarium wilt, except for the replacement of susceptible with resistant banana varieties. However, resistant varieties are not always acceptable to producers and local consumer markets. A greater awareness of the detrimental effect of chemicals on the environment has stimulated research on biological control of plant pathogens. The use of indigenous microorganims, such as non-pathogenic F. oxysporum and the bacterium Pseudomonas fluorescens, therefore, offers not only an environmentally safe but also an economical approach to combat Fusarium wilt of banana as part of an integrated disease management strategy. Non-pathogenic F. oxysporum and P. fluorescens isolates have previously been isolated from the root rhizosphere in disease suppressive soils. These isolates have the ability to reduce the incidence of Fusarium wilt in greenhouse pathogenicity trials. In this study we had hoped to expand on existing knowledge on the biological control of Fusarium wilt of banana with non-pathogenic endophytic F. oxysporum and P. fluorescens. Isolates that significantly suppress disease development in greenhouse trials were tested under field conditions. Physiological and histological studies were also performed to understand the modes of action of putative biological control agents. For the histological investigations, non-pathogenic F. oxysporum isolates were modified with green and red fluorescent proteins. Chapter 1 depicts a general overview of the biological control of Fusarium wilt diseases of agricultural crops. This chapter addresses the biology and pathogenesis of F. oxysporum, before strategies to control Fusarium wilt are discussed. The application of biological control organisms was analysed in terms of potentially useful organisms, where they can be isolated, and their possible modes of action. Finally, factors that influence biological control of Fusarium wilt diseases are discussed. A good source of prospective biocontrol agents is suppressive soils. In Chapter 2, non-pathogenic F. oxysporum isolates were collected from healthy banana roots in disease suppressive soil. Random Fragment Length Polymorphisms of the intergenic spacer region were then applied to group the non-pathogenic F. oxysporum isolates into genotypes, from which candidates were selected for biological control studies. The selected endophytes were then inoculated onto banana roots to determine their ability to act as biocontrol agents against Foc. The isolates that protected banana best against Fusarium wilt in the greenhouse, together with P. fluorescens WCS 417, were tested in the field to determine whether these isolates could effectively reduce disease incidence in an uncontrolled environment. The ability of non-pathogenic F. oxysporum and P. fluorescens WCS 417 to induce systemic resistance in Cavendish banana plants against Foc was investigated in Chapter 3 with the use of a split-root technique. The putative biocontrol agents were inoculated, separately and in combination, on one half of the roots in a split-root experiment, while the other half was challenged by a pathogenic isolate of Foc. Five different phenolic acids were assayed which included total soluble phenolic acids, non-conjugated (free acids) phenolic acids, ester-bound phenolic acids, glycosidebound phenolic acids and cell wall-bound phenolic acids. The knowledge gained will contribute to the understanding of how the biocontrol agents may induce defense responses in banana roots against Foc. Non-pathogenic isolates of F. oxysporum were transformed with the green fluorescent protein (GFP) and DsRed-Express genes in Chapter 4. These isolates were used to visualise their interactions with a GFP-transformed Foc isolate on the banana root in a non-destructive manner by means of confocal laser scanning microscopy (CLSM) in Chapter 5. The ability of non-pathogenic F. oxysporum and P. fluorescens WCS 417 to induce structural changes was also investigated with a split-root system using the CLSM. Antibioses as a mode of action of the two potential biocontrol agents was tested in vitro. Understanding the modes of action of non-pathogenic F. oxysporum and P. fluorescens WCS 417 are important when considering strategies for the implementation of these isolates in an integrated disease management strategy against Fusarium wilt of banana. / Dissertation (MSc (Plant Pathology))--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most destructive plant diseases in recorded history. The disease was first discovered in Australia in 1874 but became renowned for the severe losses it caused to export banana plantations during the 1960s in Central America. The banana export industry was saved only by replacing Gros Michel bananas, the dessert banana grown for the export market, with highly resistant Cavendish banana cultivars. Despite this apparent solution, the fungus was found to attack Cavendish bananas in the sub-tropics, where plants were believed to be predisposed to the disease by the cool winter climate. Good management practices and conventional disease management strategies have not been sufficient to reduce losses and stop the disease from spreading, and today Fusarium wilt can be found in almost all banana-producing countries of the world. Since 1988, Foc has been responsible for significant losses of Cavendish bananas in tropical Asia. The only sustainable control measure, the use of resistant varieties, is not always popular as people prefer to eat locally adopted varieties that, unfortunately, are susceptible to Foc. Sustainable Fusarium wilt management in banana depends on the improvement of existing banana cultivars or the development of novel disease management strategies. Molecular biology and biotechnology provide opportunities to introduce foreign resistance genes into existing cultivars and to develop new, environmentally friendly products that can protect susceptible bananas from Foc. Better knowledge of the Fusarium wilt pathogen, its diversity, and its mechanisms of pathogenesis will contribute significantly to developing these novel approaches for control of the disease. Molecular information on the pathogenicity of Foc, however, is limited, whereas other formae speciales of F. oxysporum have been better studied. In this thesis, Agrobacterium tumefaciens-mediated transformation of (ATMT) was employed to investigate genes responsible for pathogenicity of Foc to banana. Chapter 1 provides an overview of pathogenicity in F. oxysporum. Pathogenic and non-pathogenic forms of the fungus are first introduced to the reader, and then the biology, epidemiology and etiology of pathogenic forms of F. oxysporum are discussed. The genetic make-up and ability of the Fusarium wilt fungus to cause disease in plants concludes the first part of the review. In recent years, there has been a noted increase in the number of techniques available to study hostpathogen interactions. The second part of the review concentrates on these techniques and their applications in studying pathogenicity of the Fusarium wilt pathogen. In Chapter 2, an ATMT and screening system for Foc was developed. Five A. tumefaciens strains were evaluated for their efficiency to transform Foc with a randomly integrating vector that confers hygromycin B resistance and expression of green fluorescent protein (GFP). A small insertion mutant library of Foc was created, and a subset of transformants was characterized by determining the number of T-DNA inserts present, the location and identity of predicted genes disrupted by T-DNA insertion, and whether transformants of Foc were altered in their virulence against susceptible banana plants. In Chapter 3, the role of a known pathogenicity gene, Frp1, of the tomato pathogen F. oxysporum f. sp. lycopersici (Fol) was investigated in Foc. The first objective was to isolate and characterize the Frp1 gene in Foc, and to compare it to the homologous gene in Fol. A vector containing a modified Fol Frp1 gene was then obtained and used for targeted disruption of the gene in Foc via ATMT. Mutants in which the Frp1 gene was disrupted were then analyzed for GFP expression, culture morphology, and alterations in pathogenicity to banana. / Dissertation (MSc)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-01-10T09:15:32Z No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-10T10:58:54Z (GMT) No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-10T10:58:54Z (GMT). No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The problems caused by nematodes and by the Panama disease on banana plantations are responsible for production losses and limiting to its cultivation. In the state of Goiás there is few information about the nematode genus that affect this crop, and its relationship with the incidence of the fungus Fusarium oxysporum f. sp. cubense (Foc). This research aimed to survey the occurrence of plant parasitic nematodes, the incidence of Foc and soil attributes, and determine if there is a correlation among these factors. In January 2015, twelve banana producing regions in the state of Goiás were sampled: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara (two areas), Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral and Uruana. All sampled areas, except Morrinhos, revealed contamination with Foc, and all had different genus of nematodes. Meloidogyne sp., Helicotylenchus sp. and Rotylenchus sp. were the main genus of plant parasitic nematodes present in the banana plantations, with Meloidogyne sp. and Rotylenchus sp. the most dominant and abundant genus. We found that Pratylenchus sp. increases the population levels of F. oxysporum and that Helicotylenchus sp. has been affected by the concentration of P, Ca, Mn and the soil pH. / Os problemas fitossanitários causados por nematoides e pela doença mal-do-Panamá, na cultura da banana, são responsáveis por grandes perdas de produção ou são fatores limitantes de seu cultivo. Em Goiás, são escassas as informações sobre os gêneros de nematoides que afetam a bananicultura, bem como sua relação com a incidência do fungo Fusarium oxysporum f. sp. cubense (Foc), agente causal do mal-do-Panamá. Assim, esse trabalho teve por objetivo fazer levantamento da ocorrência de fitonematoides, da incidência de Foc e dos atributos dos solos, e determinar se há correlação entre estes fatores. Em janeiro de 2015, foram amostradas doze regiões produtoras de banana no estado de Goiás, distribuídas em onze municípios: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara, Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral e Uruana. Todas as áreas amostradas, exceto a do município de Morrinhos, apresentaram-se contaminadas com Foc, e todas apresentaram diversos gêneros de fitonematoides. Meloidogyne sp., Helicotylenchus sp. e Rotylenchus sp. foram os principais gêneros de fitonematoides presentes nos bananais no estado de Goiás, sendo Meloidogyne sp. e Rotylenchus sp. os gêneros mais dominantes e abundantes. Foi constatado que a presença de Pratylenchus sp. aumenta o nível populacional de F. oxysporum e que Helicotylenchus sp. é afetado pelos teores de P, Ca, Mn e pelo pH do solo.

To understand the flow of water as a factor that influences aquatic vegetation communities and aquatic plant dispersal, custom-made Global Positioning System (GPS) drones were used to monitor the movement of water in Aliceville Lake, Columbus Lake, and Ross Barnett Reservoir, MS. In each reservoir, the drones drifted in the wind-generated surface current. Analysis of wind speeds suggests that a certain wind speed may be necessary to overcome gradient flow. Wind direction and wind speed should be incorporated in future spatial simulation models for aquatic plant dispersal and distribution. An herbicide evaluation on Cuban bulrush (Oxycaryum cubenese) was conducted to determine what herbicides would effectively control the invasive species. Applications made prelowering were more successful than postlowering applications for all herbicides tested with glyphosate, 2,4-D, triclopyr, diquat, imazamox, and imazapyr resulting in 100% mean biomass reduction. For postlowering applications, glyphosate, triclopyr, and diquat are recommended.

Banana is the most important fruit crop in the world but ironically one of the crops least studied. This fruit constitutes a major staple food for millions of people in developing countries and also it is considered the highest selling fruit in the world market making this crop a very important export commodity for the producing countries. At the present time, one of the most significant constraints of banana production that causes significant economical losses are fungal diseases. Among these, Panama disease, also known as Fusarium wilt has been the most catastrophic. Panama disease is caused by the soil-borne fungus Fusarium oxysporum formae specialis (f.sp) cubense (FOC), which infects susceptible bananas through the roots causing a lethal vascular wilt. To date, the race 4 of this pathogen represents the most serious threat to banana production worldwide since most of the commercial cultivars are highly susceptible to this pathogen. Introduction of FOC resistance into commercial cultivars by conventional breeding has been difficult because edible bananas are sterile polyploids without seeds. Genetic transformation of banana, which has already been established in various laboratories around the world has the potential to solve this problem by transferring a FOC race 4 resistance gene into susceptible banana cultivars (eg. Cavendish cultivars). However, a FOC resistant (R) gene has not been isolated. Genes that confer resistance to Fusarium oxysporum have been isolated from tomato and melon using a map-based positional cloning approach. The tomato I2 and melon Fom-2 genes belong to the non-Toll/interleukin like receptors (TIR) subclass of nucleotide-binding site and leucine-rich repeat (NBS-LRR) R genes. These genes confer resistance only to certain races of F. oxysporum in their corresponding plant families limiting their use in other plant families. The fact that these two Fusarium resistance genes share the same basic non-TIR-NBS-LRR structure suggests a similar Fusarium resistance mechanism is shared between the families Solanaceae and Cucurbitaceae. This observation opens the possibility to find similar Fusarium resistance genes in other plant families including the Musaceae. A remarkable discovery of a population of the wild banana Musa acuminata subspecies (ssp.) malaccensis segregating for FOC race 4 resistance was made by Dr. Ivan Buddenhagen (University of California, Davis) in Southeast Asia. Research carried out at Queensland Department of Primary Industries (Australia) using this plant material has demonstrated that a single dominant gene is involved in FOC race 4 resistance (Dr. Mike Smith, unpublished results). Tissue-culture plantlets of this FOC race 4 segregating population were kindly provided to the Plant Biotechnology Program (Queensland University of Technology) by Dr. Mike Smith to be used in our research. This population holds the potential to assist in the isolation of a FOC race 4 resistance gene and other potential Fusarium resistance genes. The overall aims of this research were to isolate and characterise resistance gene candidates of the NBS-type from M. acuminata ssp. malaccensis and to identify and characterise potential Fusarium resistance genes using a combination of bioinformatics and gene expression analysis. Chapter 4 describes the isolation by degenerate PCR of five different classes of NBS sequences from banana (Musa acuminata ssp malaccensis) designated as resistance gene candidates (RGCs). Deduced amino acid sequences of the RGCs revealed the typical motifs present in the majority of known plant NBS-LRR resistance genes. Structural and phylogenetic analyses showed that the banana RGCs are related to non-TIR subclass of NBS sequences. The copy number of each class was estimated by Southern hybridisation and each RGC was found to be in low copy number. The expression of the RGCs was assessed by RT-PCR in leaf and root tissues of plants resistant or susceptible to Fusarium oxysporum f. sp. cubense (FOC) race 4. Four classes showed a constitutive expression profile whereas no expression was detected for one class in either tissue. Interestingly, a transcriptional polymorphism was found for RGC2 whose expression correlated with resistance to FOC race 4 suggesting a possible role of this gene in resistance to this devastating FOC race. Moreover, RGC2 along with RGC5 showed significant sequence similarity to the Fusarium resistance gene I2 from tomato and were chosen for further characterisation. The NBS sequences isolated in this study represent a valuable source of information that could be used to assist the cloning of functional R genes in banana. Chapter 5 describes the isolation and characterisation of the full open reading frame (ORF) of RGC2 and RGC5 cDNAs. The ORFs of these two banana RGCs were predicted to encode proteins that showed the typical structure of non-TIR-NBS-LRR resistance proteins. Homology searches using the entire ORF of RGC2 and RGC5 revealed significant sequence similarity to the Fusarium resistance gene I2 from tomato. Interestingly, the phylogenetic analysis showed that RGC2 and RGC5 were grouped within the same phylogenetic clade, along with the Fusarium resistance genes l2 and Fom-2. These findings suggest that the banana RGC2 and RGC5 are potential resistance gene candidates that could be associated with Fusarium resistance. The case of RGC2 is more remarkable because its expression was correlated to FOC race 4 resistance (Chapter 4). As a first step to test whether RGC2 has a role in FOC race 4 resistance, different expression constructs were made with the ORF of this sequence. One of the constructs contains a RGC2 putative promoter region that was successfully cloned in this work. These constructs will be used to transform susceptible banana plants that can then be challenged with FOC race 4 to assess whether resistance has been acquired by genetic complementation. The results of this thesis provide interesting insights about the structure, expression and phylogeny of two potential Fusarium resistance genes in banana, and provide a rational starting point for their functional characterisation. The information generated in this thesis may lead to the identification of a Fusarium resistance gene in banana in further studies and may also assist the cloning of Fusarium resistance genes in other plant species.

El objetivo de esta Tesis Doctoral es estudiar diferentes herramientas para el manejo de plagas y enfermedades del cultivo de la platanera. Entre las herramientas que vamos a desarrollar, se van a analizar los compuestos orgánicos volátiles (COVs) fúngicos derivados de hongos entomopatógenos (HE) y nematófagos, como fuente de metabolitos con actividad antagónica contra el picudo negro (PN) de la platanera, Cosmopolites sordidus, para su control y manejo en el campo. Así mismo, vamos a estudiar las respuestas de cultivares de plataneras a quitosano, un polisacárido biodegradable, para evaluar su posible uso en el campo como estimulante y protector de las plantas frente a plagas y patógenos, como Fusarium oxysporum f. sp. cubense. El conjunto de capítulos de esta tesis pretende sentar las bases de una estrategia de manejo sostenible de plagas y enfermedades del cultivo de la platanera, basada en el uso de COVs derivados de hongos presentes de forma natural en los cultivos, en combinación con la suplementación de quitosano en el riego, para un efecto de protección y activación de las defensas de las plataneras antes de cualquier infección de plagas y/o enfermedades. El objetivo principal de esta Tesis Doctoral es encontrar nuevas fórmulas para la gestión integrada de plagas como Cosmopolites sordidus y enfermedades de la platanera en condiciones de campo. En esta Tesis Doctoral hemos ideado enfoques sostenibles para la gestión de las plagas y enfermedades de las plataneras. Nuestros objetivos son: a) Cosmopolites sordidus (picudo negro de la platanera, PN), la principal plaga de los cultivos de plátano y, b) el hongo del marchitamiento Fusarium oxysporum f. sp. cubense Raza Tropical 4 (FocTR4), agente causante de una nueva variante extremadamente virulenta de la enfermedad del “Mal de Panamá”, que se está extendiendo rápidamente por todo el mundo. Nuestras herramientas de gestión sostenible son: a) los hongos entomopatógenos (HE, conocidos por su uso como agentes de control biológico, ACBs) aislados de campos comerciales de plátanos, b) sus compuestos orgánicos volátiles (COVs) y, c) el quitosano, un compuesto biodegradable y elicitor de la inmunidad de las plantas con actividad antimicrobiana. Damos evidencia de que los COVs de los hongos agentes de control biológico son repelentes del PN. Pueden utilizarse en los cultivos de platanera mediante estrategias de push and pull para gestionar la plaga de forma sostenible. El quitosano puede utilizarse en el riego para prevenir las defensas de la platanera local y sistémicamente. Por lo tanto, este polímero, con probada actividad antimicrobiana frente a otros patógenos de marchitamiento de Fusarium spp., podría utilizarse contra la actual pandemia en las plataneras causada por FocTR4. La capacidad de inducir reguladores del crecimiento de las plantas sostiene también el papel fertilizante del quitosano. La inducción de compuestos relacionados con la respuesta sistémica adquirida (RSA) hace que el riego con quitosano sea una herramienta para manejar también las plagas de las plataneras sobre el suelo (PN) y las enfermedades (Sigatoka). De esta manera, los COVs y el quitosano podrían ayudar a reducir el uso de agroquímicos tóxicos en los cultivos de platanera en todo el mundo.