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R C Ploetz - One of the best experts on this subject based on the ideXlab platform.
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mycosphaerella fijiensis causal agent of Black Sigatoka of musa spp found in puerto rico and identified by polymerase chain reaction
2006Co-Authors: Brian M Irish, R Goenaga, R C PloetzAbstract:Black Sigatoka, also known as Black leaf streak, is caused by Mycosphaerella fijiensis Morelet (anamorph Pseudocercospora fijiensis (Morelet) Deighton). It is the most significant disease of bananas and plantains (Musa spp.) because most of the economically important cultivars of exported and staple commodities are highly susceptible. The Caribbean is one of the few regions of the world where Black Sigatoka is not widespread. Black Sigatoka has been reported in the Bahamas, Cuba, Hispaniola, and Jamaica (2). Yellow Sigatoka, caused by M. musicola Leach (anamorph P. musae (Zimm.) Deighton), has been recognized in Puerto Rico since 1938-1939 (3). In August 2004, symptoms resembling Black Sigatoka were first observed in Anasco, Puerto Rico by extension personnel from the University of Puerto Rico. Since Black and yellow Sigatoka produce similar disease symptoms, a survey was conducted in the western banana- and plantain-production region of Puerto Rico to confirm the presence of Black Sigatoka. Leaf samples were collected from production fields near the towns of Las Marias, Maricao, and Anasco. Single-ascospore isolates were recovered using the discharge technique from moistened pseudothecia in necrotic lesions that were inverted over water agar, and ascospores were transferred to potato dextrose agar. The isolates were subcultured in potato dextrose broth for mycelium production. DNA was isolated from mycelium with the FastDNA kit (Q-Biogen, Irvine, CA) for 19 isolates. Internal transcribed spacer as well as the 5.8s rDNA regions were polymerase chain reaction amplified with primers specific to M. fijiensis or M. musicola (1). Amplification products (˜1,100 bp) were observed for 18 of the 19 isolates, 6 of which were M. fijiensis and the remaining 12 were M. musicola, while the positive controls for both species were also amplified with the respective primer pairs. M. fijiensis was recovered from production fields close to all three towns. The source of M. fijiensis in Puerto Rico is unclear, but it may have originated from introduced leaf material and/or wind dispersed ascospores from neighboring countries. The presence of Black Sigatoka in Puerto Rico will most likely increase production costs where fungicide applications will be needed to maintain yields. The USDA-ARS, Tropical Agriculture Research Station is the official Musa spp. germplasm repository for the National Plant Germplasm System. As such, efforts are underway to introduce and evaluate Black Sigatoka disease-resistant clones that can satisfy local and export market criteria. References: (1) A. Johnasen. Detection of Sigatoka leaf spot pathogens of banana by the polymerase chain reaction. Chatman, UK, Natural Resource Institute, 1997. (2) R. C. Ploetz. Plant Dis. 88:772, 2004. (3) R. H. Stover. Trop. Agric. Trinidad. 39:327, 1962.
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first report of Black Sigatoka of banana caused by mycosphaerella fijiensis on grand bahama island
2004Co-Authors: R C PloetzAbstract:Black Sigatoka, which is also known as Black leaf streak, is caused by Mycosphaerella fijiensis (anamorph Pseudocercospora [formerly Paracercospora) fijiensis]). It is the most important disease of commercially produced banana (Musa spp.) and also has a major impact on production for local consumption. Although the disease occurs throughout the humid tropics, it has been reported in the Caribbean from only Cuba, Hispaniola, and Jamaica (1). In February 2004, Black Sigatoka was observed at two isolated and widely separated sites on Grand Bahama island (26.7°N, 78.5°W and 26.7°N, 78°W) on cvs. Silk AAB and Williams AAA, and a French Horn AAB plantain. Symptoms included wet, dark brown streaks on the adaxial leaf surface, 1 to 2 × 10 mm, with chlorotic haloes. Lesions enlarged to 5 × 20 mm and developed tan, necrotic centers; large, Blackened, water-soaked areas that resulted from the coalescence of streaks were rare. The disease was confirmed by observing the following characteristics of P. fijiensis in necrotic lesions on preserved leaf specimens: simple conidiophores with a broadened base and one to several septa, straight to variously bent cercosporoid conidia as much as 100 μm long with two to several septa, and a conspicuously thickened scar at the base. Both plantings were several years old and new planting material that could have been infested with the pathogen had not been introduced since their establishment. Symptoms were not severe and were distributed sporadically in both locations. The disease was not observed at the only other large planting of banana on the island (26.6°N, 78.6°W). The sporadic and apparently new infestations of two of three banana plantings on the island suggest that the pathogen may have arrived recently via natural means, possibly from neighboring Florida (2). In contrast, Black Sigatoka appears to have spread to other islands in the Caribbean via infested propagation materials (1). To my knowledge, this is the first report of Black Sigatoka in the Bahamas, and with a previous report from Bhutan (1), represents the northernmost spread of this important disease. References: (1) J. Carlier et al. Pages 37-79 in: Diseases of Banana, Abaca and Enset. D. R. Jones, ed. CABI Publishing. Wallingford, UK, 2000. (2) R. C. Ploetz and X. Mourichon. Plant Dis. 83:300, 1999.
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first report of Black Sigatoka in florida
1999Co-Authors: R C Ploetz, Xavier MourichonAbstract:Black Sigatoka, caused by Mycosphaerella fijiensis, is widely recognized as the most important disease of banana, Musa spp. It has spread rapidly in the Western Hemisphere since it first appeared in Honduras in 1972, and is now found in the Caribbean basin in Cuba, Jamaica, and the Dominican Republic, and on the mainland from central Mexico south to Bolivia and northwestern Brazil (2). In October 1998, symptoms of Black Sigatoka (2) were observed on several different cultivars in a collection at the University of Florida's Tropical Research and Education Center (TREC) in Homestead (25°30′ N, 80°30′ W). During preliminary surveys, the disease was found at four of eight locations in a 15 km2 area to the north of TREC. Disease severity, rated as the youngest leaf spotted (YLS), averaged 4.8 on the most susceptible cultivar, Rajapuri, at one of the locations. The extent and history of damage at this site indicated that Black Sigatoka had been there for at least 3 to 4 years. The prevailing east to west winds ...
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first report of Black Sigatoka in bolivia
1997Co-Authors: J C Tejerina, R C Ploetz, G Meriles, R H Stover, S RomanoffAbstract:Black Sigatoka, caused by Mycosphaerella fijiensis, is the most important disease of banana worldwide (1). It affects cultivars of the Cavendish subgroup that are used for export and important, locally consumed cooking and dessert bananas and plantains, reducing yields by 50% or more. Black Sigatoka first appeared in the Western Hemisphere in 1972 in Honduras, and has spread to all other countries in Central America (1980), Mexico (1980), and the following islands in the Caribbean: Cuba (1992), Hispanola (Dominican Republic) (1996), and Jamaica (1994). In South America, the disease has spread to Colombia (1981), Ecuador (1986), Venezuela (1992), and Peru (1994) (1). In June 1996, symptoms of the disease were observed in the San Carlos area in the western Chapare region of Bolivia. During surveys conducted in March and June 1997, several Cavendish clones, Dulce Cajita (Pisang mas), Guineo (Silk), Morado (Red), and Platano (French and Horn plantain) were affected. In each of eight major banana-producing are...
Turner B. Sutton - One of the best experts on this subject based on the ideXlab platform.
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research burrowing nematode resistance of Black Sigatoka resistant banana hybrids
1998Co-Authors: D H Marin, Turner B. Sutton, K R Barker, D T Kaplan, Charles H OppermanAbstract:Resistance of Black Sigatoka resistant hybrids FHIA-01, FHIA-02, FHIA-03, and FHIA-21 to the burrowing nematode, Radopholus similis, was assessed under greenhouse conditions. Resistance was evaluated by inoculating the hybrid plants with 200 monoxenically-reared nematodes/plant. Banana plants produced by tissue culture were grown in 0.4-L Styrofoam cups, containing a 1:1 mix of a coarse and a fine sand, at 27 C and 80% RH. Plants were allowed to acclimate and grow for 4 weeks prior to inoculation. Plant height, fresh shoot and root weights, nematode population levels, and root necrosis (0-100%) were determined 8 weeks after inoculation. Pisang Jan Buaya (accession III-106) and Grande Naine (Musa AAA, Cavendish subgroup) were used as resistant and susceptible controls, respectively. Final nematode population numbers and root-necrosis indices did not differ among FHIA-01, FHIA-03 and the susceptible control (Grande Naine). Although R. similis reproduced poorly in Pisang Jari Buaya, ex
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Characterization of Benomyl Resistance in Mycosphaerella fijiensis, Cause of Black Sigatoka of Banana, in Costa Rica.
1998Co-Authors: Ronald A Romero, Turner B. SuttonAbstract:Sixty-eight and eighty-six percent of monoascosporic isolates of Mycosphaerella fijiensis from two banana plantations in Costa Rica, in which benomyl was used for ≈10 years to control Black Sigatoka, were resistant to benomyl in February and November 1994, respectively. No resistance to benomyl was detected in isolates collected during February 1994 from farms with no history of benomyl use that were located ≈50 km from the nearest banana plantations. Only 1% of isolates was resistant to benomyl in a sample taken during November 1994. In three additional banana farms where benomyl had not been used for 3 to 5 years before sampling, ben-omyl resistance persisted at a high frequency. Benomyl-resistant and -sensitive isolates were distributed equally throughout the range of isolate sensitivity to propiconazole, indicating no relationship between resistance to benomyl and lower sensitivity to propiconazole but double resistance to these two compounds. Five benomyl-resistant and five benomyl-sensitive isolates of M. fijiensis were inoculated to banana plants under greenhouse conditions. Benomyl-resistant isolates were more aggressive than benomyl-sensitive isolates, as determined by measures of disease severity, incubation time, and number of lesions at 40 days after inoculation.
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sensitivity of mycosphaerella fijiensis causal agent of Black Sigatoka of banana to propiconazole
1997Co-Authors: Ronald A Romero, Turner B. SuttonAbstract:ABSTRACT One hundred monoascosporic isolates of Mycosphaerella fijiensis were collected in February and November 1994 from each of two banana (Musa spp.) plantations in Costa Rica. Locations at San Pablo and Coopecariari had been sprayed with propiconazole for the past 7 years to control Black Sigatoka. One hundred monoascosporic isolates from a third location, San Carlos, with no history of fungicide use, also were tested for sensitivity to propiconazole. Fifty percent effective concentration (EC(50)) values were calculated for individual isolates by regressing the relative inhibition of colony growth against the natural logarithm of the fungicide concentration. In the February sample, the mean EC(50) values for San Pablo and Coopecariari populations were 0.06 and 0.05 mug a.i. ml(-1), respectively, which were not statistically different (P = 0.05). The mean EC(50) value of the population at San Carlos was 0.008 mug a.i. ml(-1), which was significantly lower (P = 0.001) than the mean EC(50) values obtained at San Pablo and Coopecariari. Frequency distributions of EC(50) values of isolates from the three populations collected in February showed that 80% of isolates from San Pablo and Coopecariari had EC(50) values greater than the highest EC(50) value from San Carlos, indicating a significant shift in reduced sensitivity to propiconazole. Isolates collected in November 1994, after eight treatments of propiconazole at San Pablo and Coopecariari, showed a significant increase in mean EC(50) values compared with the means observed in February. The high proportion of isolates with reduced sensitivity to propiconazole may account for the unsatisfactory control of Black Sigatoka between 1992 and 1993 in the two banana plantations at San Pablo and Coopecariari.
Pablo Chong - One of the best experts on this subject based on the ideXlab platform.
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pfcyp51 exclusively determines reduced sensitivity to 14α demethylase inhibitor fungicides in the banana Black Sigatoka pathogen pseudocercospora fijiensis
2019Co-Authors: Rafael Eduardo Arango Isaza, Pablo Chong, Harold J G Meijer, Aikaterini Eleni Vichou, H J Schouten, Gert H J KemaAbstract:The haploid fungus Pseudocercospora fijiensis causes Black Sigatoka in banana and is chiefly controlled by extensive fungicide applications, threatening occupational health and the environment. The 14α-Demethylase Inhibitors (DMIs) are important disease control fungicides, but they lose sensitivity in a rather gradual fashion, suggesting an underlying polygenic genetic mechanism. In spite of this, evidence found thus far suggests that P. fijiensis cyp51 gene mutations are the main responsible factor for sensitivity loss in the field. To better understand the mechanisms involved in DMI resistance, in this study we constructed a genetic map using DArTseq markers on two F1 populations generated by crossing two different DMI resistant strains with a sensitive strain. Analysis of the inheritance of DMI resistance in the F1 populations revealed two major and discrete DMI-sensitivity groups. This is an indicative of a single major responsible gene. Using the DMI-sensitivity scorings of both F1 populations and the generation of genetic linkage maps, the sensitivity causal factor was located in a single genetic region. Full agreement was found for genetic markers in either population, underlining the robustness of the approach. The two maps indicated a similar genetic region where the Pfcyp51 gene is found. Sequence analyses of the Pfcyp51 gene of the F1 populations also revealed a matching bimodal distribution with the DMI resistant. Amino acid substitutions in P. fijiensis CYP51 enzyme of the resistant progeny were previously correlated with the loss of DMI sensitivity. In addition, the resistant progeny inherited a Pfcyp51 gene promoter insertion, composed of a repeat element with a palindromic core, also previously correlated with increased gene expression. This genetic approach confirms that Pfcyp51 is the single explanatory gene for reduced sensitivity to DMI fungicides in the analysed P. fijiensis strains. Our study is the first genetic analysis to map the underlying genetic factors for reduced DMI efficacy.
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a new mechanism for reduced sensitivity to demethylation inhibitor fungicides in the fungal banana Black Sigatoka pathogen pseudocercospora fijiensis
2018Co-Authors: Caucasella Diaztrujillo, Pablo Chong, Ioannis Stergiopoulos, Viviane Cordovez, Mauricio Guzman, Pierre J G M De Wit, Harold J G Meijer, Gabriel Scalliet, Helge SierotzkiAbstract:The Dothideomycete Pseudocercospora fijiensis, previously Mycosphaerella fijiensis, is the causal agent of Black Sigatoka, one of the most destructive diseases of bananas and plantains. Disease management depends on fungicide applications, with a major contribution from sterol demethylation-inhibitors (DMIs). The continued use of DMIs places considerable selection pressure on natural P. fijiensis populations, enabling the selection of novel genotypes with reduced sensitivity. The hitherto explanatory mechanism for this reduced sensitivity was the presence of non-synonymous point mutations in the target gene Pfcyp51, encoding the sterol 14α-demethylase enzyme. Here, we demonstrate a second mechanism involved in DMI sensitivity of P. fijiensis. We identified a 19-bp element in the wild-type (wt) Pfcyp51 promoter that concatenates in strains with reduced DMI sensitivity. A polymerase chain reaction (PCR) assay identified up to six Pfcyp51 promoter repeats in four field populations of P. fijiensis in Costa Rica. We used transformation experiments to swap the wt promoter of a sensitive field isolate with a promoter from a strain with reduced DMI sensitivity that comprised multiple insertions. Comparative in vivo phenotyping showed a functional and proportional up-regulation of Pfcyp51, which consequently decreased DMI sensitivity. Our data demonstrate that point mutations in the Pfcyp51 coding domain, as well as promoter inserts, contribute to the reduced DMI sensitivity of P. fijiensis. These results provide new insights into the importance of the appropriate use of DMIs and the need for the discovery of new molecules for Black Sigatoka management.
Rodomiro Ortiz - One of the best experts on this subject based on the ideXlab platform.
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diploid banana hybrids tmb2x5105 1 and tmb2x9128 3 with good combining ability resistance to Black Sigatoka and nematodes
2003Co-Authors: A Tenkouano, D Vuylsteke, Rony Swennen, J Okoro, D Makumbi, Rodomiro OrtizAbstract:Diploid Banana Hybrids TMB2x5105-1 and TMB2x9128-3 with Good Combining Ability, Resistance to Black Sigatoka and Nematodes A. Tenkouano, D. Vuylsteke1, J. Okoro, D. Makumbi, R. Swennen2, and R. Ortiz Crop Improvement Division, International Institute of Tropical Agriculture, PMB 5320, Oyo Road, Ibadan, Nigeria (International mailing address: c/o L.W. Lambourn & Co., 26 Dingwall Road, Croydon CR9 3EE, England)
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influence of Black Sigatoka disease on the growth and yield of diploid and tetraploid hybrid plantains
1998Co-Authors: K Craenen, Rodomiro OrtizAbstract:Plantain and banana (Musa spp.) are important staple food crops in the humid forest and mid-altitude agro-ecologies of sub-Saharan Africa. Black Sigatoka, caused by Mycosphaerella fijiensis, is an airborne fungal disease which attacks the leaves of the Musa plant. It is commonly considered the major constraint to plantain production in West Africa. The disease causes severe leaf necrosis and reduces yield by 30 to 50%. Twenty euploid hybrids, derived from interspecific interploidy crosses were selected for a range of host responses to Black Sigatoka. The performance of these hybrids was compared with that of their parents to determine the influence of the disease on growth parameters and components of yield. There were significant differences for all components of Black Sigatoka resistance, growth parameters, and yield components among the hybrids. For diploid hybrids, which often had a short growth cycle, early flowering, or both, the disease incubation time was significantly correlated with days to fruit filling (P<0.05). However, for tetraploid hybrids that had a long growth cycle and delayed flowering, the correlation was not significant (P ≥ 0.05). For diploid and tetraploid hybrids, the disease evolution time and the disease development time were both correlated (P < 0.05) with days to fruit filling. The bunch weight of tetraploid hybrids was correlated (P < 0.05) with the disease development time that was easily scored by the youngest leaf spotted at flowering (ρ = 0.933; P < 0.001). Hence, Black Sigatoka resistant hybrids with potential high yield could be selected efficiently by recording the youngest leaf spotted at flowering.
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effect of the bs1 gene in plantain banana hybrids on response to Black Sigatoka
1997Co-Authors: K Craenen, Rodomiro OrtizAbstract:Use of resistant host genotypes is an important component of an integrated approach to control Black Sigatoka, a disease caused by the fungus Mycosphaerella fijiensis Morelet. The objective of the present research was to determine the role of the major gene for Black Sigatoka resistance (bs1) in the host response to this disease. Euploid hybrids with a known genotype for the bs1 locus were derived from triploid-diploid crosses of two French plantains and a diploid wild banana, and were assessed for their host response to Black Sigatoka in plant and ratoon crops in the humid forest zone of Nigeria. Host response was determined at flowering by recording the number of standing leaves, the youngest leaf with symptoms, the youngest leaf spotted, the total leaf area attacked by Black Sigatoka, and an index of the leaves spotted. An analysis of frequency distribution in each segregating population showed that almost all the traits displayed a normal distribution across ploidy level. This suggests that additive gene action plays an important role in the host-plant response to the fungus. Heritability, repeatibility, and intraclass correlations were calculated. The environment and the genotype-by-environment interaction significantly affected the host response to Black Sigatoka, which explains the low repeatibility of all traits. The intrafamily variation was larger than the interfamily variation, and most of the genetic variation in each family depended on the individual genotypes, regardless of their ploidy. The additive effect of, and the intralocus interaction at, the bs1 locus on host response to Black Sigatoka were established by a one-way analysis of variance and regression analyses. Intralocus interaction in the bs1 locus apparently regulates the appearance of symptoms on the leaf surface, whereas the additive effect and the intralocus interaction of the bs1 locus affect disease development in the host plant. Therefore, the gene action(s) at the bs1 locus may provide durable resistance to Black Sigatoka by slowing down disease development in the host plant.
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effect of the Black Sigatoka resistance locus bs1 and ploidy level on fruit and bunch traits of plantain banana hybrids
1996Co-Authors: K Craenen, Rodomiro OrtizAbstract:Plantain (Musa spp., AAB group) cultivation is threatened by Black Sigatoka, an airborne fungal (Mycosphaerella fijiensis Morelet) leaf spot disease. Several traits in plantains and bananas are mainly affected by major genes. The host resistance response to Black Sigatoka is under the control of at least three different genes, one major recessive gene bs1 and two other independent additive alleles. Diploid and tetraploid plantain hybrids were evaluated for bunch weight, fruit weight, fruit length and fruit circumference. The F1 euploid hybrids were derived from interspecific crosses between the resistant diploid wild banana ‘Calcutta 4’ and the susceptible triploid plantain cultivars ‘Obino l'Ewai’ and ‘Bobby Tannap’. Linear and multiple regression models, coefficients of determination, and Durbin-Watson statistics were used to determine the single and combined effects of the major locus for Black Sigatoka resistance and ploidy on the different traits in the progenies. Differences in yield were mainly due to changes in weight and girth of fruit, which are affected by Black Sigatoka disease. The combined effect of ploidy and resistance to Black Sigatoka was partially responsible for the quantitative trait variation in yield. As a result of the gene interaction in the Black Sigatoka resistance locus bs1, the partially resistant and less susceptible phenotypes showed higher yield than their more susceptible full sibs.
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plantain derived diploid hybrids tmp2x with Black Sigatoka resistance
1995Co-Authors: D Vuylsteke, Rodomiro OrtizAbstract:Plantain (Musa spp., AAB group), a triploid (2n = 3x = 33) giant perennial herb of the tropics, is a natural interspecific hybrid between the two wild banana species M. acuminata Colla. and M. balbisiana Colla. These diploid species contributed the A and B genomes, respectively (Simmonds, 1962). Triploidy makes plantain crossbreeding difficult but not impossible (Swennen and Vuylsteke, 1993). As such, plantain progenies were obtained when triploid plantains were crossed with diploid M. acuminata clones (Vuylsteke et al., 1993c). Genetic improvement of plantain is required because its sustainable production is threatened by increasing disease and pest pressure (Vuylsteke et al., 1993b). One of the major constraints is the Black Sigatoka leaf spot disease (Mycosphaerella fijiensis Morelet), which causes yield losses of at least 33% (Mobambo et al., 1993). Production and cultivation of resistant cultivars are generally considered the most appropriate means to control the disease. The International Institute of Tropical Agriculture (IITA) targets the development of improved plantain germplasm. So far, 14 improved plantain-derived tetraploid (4x) hybrids with Black Sigatoka resistance have been selected for multilocational testing and further cultivar release by national agricultural research programs (Vuylsteke et al., 1993d). In addition to the tetraploid hybrids, progenies with other ploidies were also recovered from the 3x x 2x crosses, diploids (2x) being most numerous (Vuylsteke et al., 1993c). Plantainderived diploids play an important role in
Paolo Di Mascio - One of the best experts on this subject based on the ideXlab platform.
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enterobacter cloacae an endophyte that establishes a nutrient transfer symbiosis with banana plants and protects against the Black Sigatoka pathogen
2019Co-Authors: Fernanda M. Prado, Gloria Macedoraygoza, Benjamin Valdezsalas, Katia R Prieto, Lydia F Yamaguchi, Massuo J Kato, Blondy B Cantocanche, Monica Carrillobeltran, Paolo Di MascioAbstract:Banana (Musa spp.) is an important crop worldwide, but Black Sigatoka disease caused by the fungus Pseudocercospora fijiensis threatens fruit production. After exhaustive isolation of endophytic microbes from banana plants, we examined the potential of Enterobacter cloacae and Klebsiella pneumoniae to transfer organic nitrogen and support plant growth in nutrient limited soils. Both bacteria were also found to be antagonistic against P. fijiensis strains. The two bacterial isolates were identified by MALDI-TOF mass spectrometry and corroborated by 16rRNA sequence analysis. Plant growth promotion (PGP) traits, including nitrogen fixation, phosphate solubilization, indole-3-acetic acid (IAA) and siderophore production, and ACC deaminase (ACCd), were evaluated using microbiological approaches. To measure the effects on plant growth, the two plant bacteria and an E. coli as non-endophyte, were inoculated weekly for 60 days as active cells (AC) and heat-killed cells (HKC) into plant microcosms without nutrients and compared to a water only treatment, and a mineral nutrients solution (MMN) treatment. All bacterial treatments stimulated growth parameters and prevented accelerated senescence, which was observed for water and mineral nutrients solution (MMN) treatments (controls). Of the bacterial treatments, only the E. cloacae (AC) treatment resulted in a sustainable symbiosis with banana plants. After 60 days, only those plants inoculated with E. cloacae showed intracellular bacteria within root cells. Plants died after 15 days of being irrigated with water; irrigation with MMN enabled plants to develop some new leaves, but plants lost weight (-30%) during the same period. To evaluate the transference of organic N from bacteria into the plants, bacteria were labeled with 15NH4Cl or Na15NO3. The 15N on plant tissues was measured by pheophytin isotopomers abundance. The relative abundance of the isotopomers m/z 872.57, 873.57, 874.57, 875.57, 876.57 unequivocally demonstrate that plants acquire 15N atoms directly from bacterial cells, using them as a source of N, to favor plant growth in nutrients absence. These results reveal a new alternative to promote growth and health of crops using endophytic bacteria such as E. cloacae as an alternative to agrochemicals for banana cultivation.
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Data_Sheet_1_Enterobacter cloacae, an Endophyte That Establishes a Nutrient-Transfer Symbiosis With Banana Plants and Protects Against the Black Sigatoka Pathogen.docx
2019Co-Authors: Gloria M. Macedo-raygoza, Fernanda M. Prado, Paolo Di Mascio, Katia R Prieto, Lydia F Yamaguchi, Massuo J Kato, Benjamín Valdez-salas, Blondy B. Canto-canché, Monica Carrillo-beltrán, James F. WhiteAbstract:Banana (Musa spp.) is an important crop worldwide, but Black Sigatoka disease caused by the fungus Pseudocercospora fijiensis threatens fruit production. In this work, we examined the potential of the endophytes of banana plants Enterobacter cloacae and Klebsiella pneumoniae, as antagonists of P. fijiensis and support plant growth in nutrient limited soils by N-transfer. The two bacterial isolates were identified by MALDI-TOF mass spectrometry and corroborated by 16S rRNA sequence analysis. Both bacteria were positive for beneficial traits such as N-fixation, indole acetic acid production, phosphate solubilization, negative for 1-aminocyclopropane 1-carboxylic acid deaminase and were antagonistic to P. fijiensis. To measure the effects on plant growth, the two plant bacteria and an E. coli strain (as non-endophyte), were inoculated weekly for 60 days as active cells (AC) and heat-killed cells (HKC) into plant microcosms without nutrients and compared to a water only treatment, and a mineral nutrients solution (MMN) treatment. Bacterial treatments increased growth parameters and prevented accelerated senescence, which was observed for water and mineral nutrients solution (MMN) treatments used as controls. Plants died after the first 20 days of being irrigated with water; irrigation with MMN enabled plants to develop some new leaves, but plants lost weight (−30%) during the same period. Plants treated with bacteria showed good growth, but E. cloacae AC treated plants had significantly greater biomass than the E. cloacae HKC. After 60 days, plants inoculated with E. cloacae AC showed intracellular bacteria within root cells, suggesting that a stable symbiosis was established. To evaluate the transference of organic N from bacteria into the plants, the 3 bacteria were grown with 15NH4Cl or Na15NO3 as the nitrogen source. The 15N transferred from bacteria to plant tissues was measured by pheophytin isotopomer abundance. The relative abundance of the isotopomers m/z 872.57, 873.57, 874.57, 875.57, 876.57 unequivocally demonstrated that plants acquired 15N atoms directly from bacterial cells, using them as a source of N, to support plant growth in restricted nutrient soils. E. cloacae might be a new alternative to promote growth and health of banana crops.
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Singlet molecular oxygen generation by light-activated DHN-melanin of the fungal pathogen Mycosphaerella fijiensis in Black Sigatoka disease of bananas.
2014Co-Authors: Miguel J. Beltran-garcia, Fernanda M. Prado, Marilene Silva Oliveira, David Ortiz-mendoza, Alexsandra Cristina Scalfo, Adalberto Pessoa, Marisa H. G. Medeiros, James F. White, Paolo Di MascioAbstract: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.