Pathogen Colletotrichum Research Articles

Cover: Journal of Basic Microbiology. 2/2021

Journal of Basic MicrobiologyVolume 61, Issue 2 p. 75-75 COVER PICTUREFree Access Cover: Journal of Basic Microbiology. 2/2021 First published: 01 February 2021 https://doi.org/10.1002/jobm.202170005AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Cover illustration: Symptoms of wolfberry fruits inoculated with the pathogen Colletotrichum fioriniae LB8. (Photo: Lijun Ling, College of Life Science, Northwest Normal University, Lanzhou, People's Republic of China) Volume61, Issue2February 2021Pages 75-75 RelatedInformation

Anthracnose Disease of <i>Capsicum annuum </i>L. and Its Bio Control Management: A Review

Capsicum annuum L. is an important tropical and subtropical vegetable and spice crop due to its high consumption, nutritional and cash value to farmers and consumers. It has a specific nutritional value due to presence of biochemical compounds such as capsteam; a volatile fatty oil, capsaicinoids, carotenoids, potassium, folic acid, protein, fiber, mineral elements and vitamins etc. Despite serious threats have been posed by many fungal pathogens to the chili crop worldwide; maximum losses occur in capsicum are due to the Anthracnose disease caused by fungal pathogen Colletotrichum sp. The biocontrol management is playing crucial role and promoted widely in control of Anthracnose disease, mainly because of its ability to control variety of fungal diseases and also enhancing the crop production in an environment friendly manner. This review article attempts to highlight an occurrence of Anthracnose disease on an economically important Capsicum annuum L. (chilli) along with its biocontrol management strategies.

Elicitation of fruit defense response by active edible coatings embedded with phenylalanine to improve quality and storability of avocado fruit

Edible coatings attract high research attention as an effective natural approach for maintaining fresh agricultural produce quality and storability. In this study, a series of polysaccharide-based coatings that contain, for the first time, an elicitor of fruit defense response, phenylalanine, were developed and applied on avocado fruit. After an initial screening of a series of polysaccharides coatings, the chitosan and carboxymethyl cellulose with stearic acid (CMC + StA) were chosen, and phenylalanine elicitor was added then to the polysaccharide matrices. These active edible coatings of either chitosan or CMC + StA that contained phenylalanine significantly reduced the fruit's natural decay caused by the fungal pathogens Colletotrichum and Alternaria. The coated avocado fruit has also demonstrated higher resistance to storage at sub-optimal temperature and showed less pitting, decay, and internal browning. The observed cold resistance correlated with a minor transcript upregulation of several genes as lipoxygenase, heat-shock protein, and several transcripts in the phenylpropanoid pathway. Interestingly, the coated fruit had a better flavor than the control fruit. Taken together, the reported results point to the ability of these new edible coatings to significantly increased fruit resistance to fungal pathogens and cold stress while maintaining the fruit quality and storability and improving their taste.

Molecular and pathological characterization of isolates of Colletotrichum falcatum Went. causing red rot in sugarcane

Red rot also known as cancer of sugarcane is caused by a pathogen Colletotrichum falcatum (Went.). The disease has a devastating effect as it hinders sugarcane cultivation worldwide. The major way to manage the disease is to develop the disease resistant varieties which require the study of genetic diversity of the pathogen. The present research aim was to study the pathogenic and molecular diversity among the isolates of red rot pathogen collected during surveys of major sugarcane growing areas of Punjab, Haryana and Uttar Pradesh states. Pathogenic assay of isolates on fourteen host differentials grouped them into eight groups on the basis of reaction expressed and virulence frequency. The molecular variation among the isolates using ISSR marker analysis showed high level of polymorphism, which confirmed the variation in virulence pattern of isolates. Polymorphism information content (PIC) and similarity coefficient values varied in the range of 0.227 to 0.321 and 0.29 to 0.93, respectively. The dendrogram grouped isolates in different clusters which reveal considerable level of molecular diversity among the isolates. However, the genetic diversity estimates based on ISSR markers did not show any correspondence with pathogenic variation of the isolates which could be due to same geographical conditions. Nucleotide sequences analysis of the ribosomal DNA (rDNA) genes using universal ITS primers showed the nucleotide variation in the isolates which could be due to base substitution at one to four sites which suggested its role in the origin of virulence and diversity in Colletotrichum falcatum. The presence of ITS variation in the virulent isolates suggested its role in the origin of virulence and diversity in Colletotrichum falcatum. But this needs further verification using proteomic approach for the identification of proteins expressed in relation to pathogenicity.

Efficacy of fungicides in control of turmeric leaf spot caused by Colletotrichum capsici at Tepi, Southwestern Ethiopia

Turmeric leaf spot, caused by the pathogen Colletotrichum capsici, is the greatest damaging disease that limits the production and productivity of turmeric, and reduces qualitative and quantitative rhizome yields in Southwestern Ethiopia. A field trial was conducted to evaluate the efficacy of different fungicides against a disease epidemic of turmeric leaf spot in Southwestern Ethiopia. The field experiment was performed at Tepi Agricultural Research Center during the 2019 and 2020 main cropping seasons using four fungicides: Ethiozeb 80% WP (mancozeb), Prozole 255 EC (propiconazole), Mancolaxyl 72% WP (mancozeb + metalaxyl) and Ridomil Gold MZ 68 WG (metalaxyl-M), which were applied either as seed rhizome treatments plus foliar spray, or as foliar spray alone for control of leaf spot infection. The field experiment was laid out in a randomized complete block design with nine treatments and three replications. The results of the experiment indicated that both rhizome treatment + foliar spray, and foliar fungicide spray treatments significantly affected the turmeric leaf spot epidemics. The effect of the foliar spray Prozole 255 EC (propiconazole) was significantly higher than the other treatments in reducing disease severity (27.0) and maximizing rhizome fresh yield (34.1 ton/ ha). The maximum cost benefit ratio (1:2.65) was achieved by the foliar spray fungicide Prozole 255 EC (propiconazole). Amongst different fungicides considered, the foliar spray Prozole 255 EC (propiconazole) reduced leaf spot disease incidence up to 47.1% over the control on the last day of disease evaluation. The whole outcome of this experiment showed that foliar Prozole 255 EC (propiconazole) fungicide sprays were effective in alleviating the epidemic of turmeric leaf spot and boosting turmeric production and productivity.

Bet v 1 potential allergens are involved in anthracnose resistance of strawberry varieties

BACKGROUND: Bet v 1 family identified as one major plant food allergen class, is highly homologous to pathogenesis-related protein 10 (PR-10), but its biological function involved in disease resistance is still unclear. OBJECTIVE: This study aims to investigate whether Bet v 1 potential allergens participate in the resistance of berry crops against fungal pathogen. METHODS: Allergenicity of Bet v 1 proteins in strawberry (Fragaria) was evaluated by bioinformatics methods. Their expression in response to anthracnose and between susceptible and resistance varieties was analyzed. RESULTS: 19 Bet v 1 homologous proteins were identified and 15 of them were considered as allergen candidates. RNA-seq analysis indicated most of these Fra a 1s expressed in fruits could be largely induced by the invasion of anthracnose pathogen Colletotrichum. The mRNA level of fruit major allergen Fra a 1.05 in the resistant variety Shenyang (SY) was 20∼50 fold higher compared with those in the susceptible cultivar and two diploid wild species. Immunoblotting using Birch (Betula pendula) Bet v 1 allergen-specific IgG antibody confirmed the large-scale accumulation of potential cross-reactive antigens in SY fruit. CONCLUSIONS: Strawberry Bet v 1 potential allergens exhibit their correspondence with anthracnose resistance that might be instructive to future breeding strategies.

Pemanfaatan Khamir Antagonis untuk Memperpanjang Umur Simpan dan Mengendalikan Penyakit Antraknosa Buah Pepaya

Pepaya adalah buah klimakterik yang memiliki umur simpan pendek dan potensi gangguan penyakit antraknosa pada saat tahap pascapanen yang disebabkan oleh patogen Colletotrichum gloeosporioides. Tujuan dari penelitian ini adalah mengkaji keefektifan beberapa spesies khamir antagonis untuk memperpanjang umur simpan dan mengendalikan penyakit antraknosa pada pascapanen buah pepaya Callina. Penelitian ini dilaksanakan di kebun pepaya Desa Kanaga, Kabupaten Lebak, Banten pada November 2018 sampai Juli 2019 dan Laboratorium Pascapanen AGH, IPB pada bulan Maret sampai dengan Juli 2019. Penelitian ini menggunakan rancangan kelompok lengkap teracak dengan perlakuan lima jenis khamir yaitu Cryptococcus albidus Yp, Aureobasidium pullulans Dmg 30 DEP, Rhodotorula minuta Dmg 16 BEP, Candida tropicalis Lm 13 BE, dan Pseudozyma hubeiensis Dmg 18 BEP, dan sebagai pembanding perlakuan fungisida berbahan aktif azoksistrobin serta tanpa perlakuan sebagai kontrol. Hasil penelitian menunjukkan penggunaan khamir Candida tropicalis, Aureobasidium pullulans, dan Cryptococcus albidus dapat memperpanjang umur simpan buah pepaya Callina masing-masing 12.6, 12.4, dan 12.2 hari, lebih lama dibandingkan kontrol yang hanya 7 hari, dan efektif mengendalikan penyakit antraknosa dengan tingkat penekanan secara berturut-turut 58.33%, 54.17%, dan 50.00%, selama penyimpanan. Penggunaan khamir antagonis tidak mempengaruhi mutu fisik dan kimia buah pepaya Callina.
 Kata kunci: buah klimakterik, Colletotrichum gloeosporioides, pascapanen

Antifungal Activity of Gelatin-Tapioca Starch Film and Coating Containing Copper Nanoparticles against Colletotrichum gloeosporioides Causing Anthracnose

This study aimed to fabricate a nontoxic coating containing copper nanoparticles (CuNPs) to protect fruits from pathogenic Colletotrichum gloeosporioides causing anthracnose on several tropical fruits. We used a green approach, in which CuNPs were synthesized by reducing CuSO4 with ascorbic acid in the presence of gelatin and glycerol as the capping agents. The formation of CuNPs was confirmed by UV-vis absorption spectra of the reaction mixture, which showed a surface plasmon resonance peak at 578–594 nm. The x-ray diffraction spectrum of the CuNPs indicated the presence of mostly metallic copper with some minor impurities of Cu2O, CuO, and Cu(OH)2. Transmission electron microscopy (TEM) images and dynamic light scattering studies showed that the sizes of 90% of CuNPs were in 100–300 nm range. A 30–50 nm capping layer of gelatin surrounding CuNPs can be observed in the TEM images. Comparing FTIR spectra of the used reagents and CuNPs confirmed the depletion of ascorbic acid, as well as the gelatin layer protecting CuNPs. The synthesized CuNPs showed dose-dependent antifungal activity against C. gloeosporioides with 100% growth inhibition at 200 ppm copper. Gelatinized tapioca starch was then added to the CuNPs solution to obtain a film-forming mixture to produce stand-alone composite films on Petri dishes and coatings on mangoes. C. gloeosporioides could not grow on the surface of nutrient agar in contact with the films containing 245 ppm CuNPs, while they grew normally on control films without CuNPs. For the in vivo antifungal tests on mangoes, both the control and the CuNPs-containing coatings equally inhibit fungal growth, possibly due to the low oxygen permeability of the protein and starch components in the films. This study thus demonstrated the potential applications of composite coatings using biodegradable polymers that contain CuNPs in postharvest protecting fruits from phytopathogenic fungi.

Dry Bean and Anthracnose Development From Seeds With Varying Symptom Severity.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is a damaging seed-transmitted disease of dry beans that causes reduced seed quality and yield. Seed-to-seedling transmission of C. lindemuthianum has been documented as high as 15% in asymptomatic seeds under greenhouse conditions. Increasing pathogen colonization in seeds has been correlated with increasing anthracnose seed symptoms via quantitative PCR (qPCR), but stem colonization has not been quantified. Previous studies also have characterized seed yield and quality losses caused by planting C. lindemuthianum-infected seeds, but none evaluated the effect of growing asymptomatic seeds on disease and plant development under field conditions. A real-time qPCR assay was developed in this study and used to detect C. lindemuthianum in the stems of seedlings as early as 15 days after planting. Field trials measured the seed-to-seedling transmission of C. lindemuthianum across levels of anthracnose symptoms in seeds ranging from healthy to severely discolored. Results from these two field trials indicated that emergence and yield decreased and foliar symptoms, pathogen detection, and incidence of symptoms on progeny seeds increased as the severity of infection in planted seeds increased. In both years, planting asymptomatic seeds resulted in higher anthracnose severity than planting healthy seeds. Yield, seed weight, and incidence of symptoms on progeny seeds were not higher in asymptomatic seeds than in healthy seeds in 2014, when moderate disease pressure was observed. However, these factors were significantly different in 2015, when anthracnose severity was driven up to 75% by conducive weather conditions. This serves as a strong warning to growers that planting seed grown in a field where anthracnose was present, even if those seeds are asymptomatic, can result in yield and quality losses. Planting certified dry bean seed is always recommended.

Resistance to Anthracnose (Colletotrichum lentis, Race 0) in Lens spp. Germplasm

Anthracnose, caused by the fungal pathogen Colletotrichum lentis, is a severe disease of lentil (Lens culinaris) causing premature defoliation, necrotic stem lesions that lead to plant wilting and death in susceptible varieties. Two races of C. lentis (0 and 1) have been described so far. Race 0 is the most virulent one and limited genetic resistance is available to date. To address this scarcity of resistance, we screened a germplasm collection covering different Lens spp. originating from different countries for C. lentis race 0 resistance. Leaf and stem damage and plant mortality were assessed on seedlings inoculated under controlled conditions. A significant variability was observed among accession. Most of the collection studied was highly susceptible, but some levels of resistance were identified in about 15% of the accessions. The highest levels of resistance were identified in L. ervoides accessions PI572330, PI572334 and PI572338. Moderate resistance was also identified in 10 L. culinaris ssp. culinaris accessions but not in the remaining species studied. Selected accessions showed potential to integrate several breeding programs.

Molecular characterization of native pink pigmented facultative methylotrophs of chilli and their induced systemic resistance mechanism in management of anthracnose

Aim: This study aimed to assess the plant growth promotional ability and biocontrol efficiency of native pink pigmented facultative methylotrophs (PPFMs) of chilli for management of chilli anthracnose disease through induced systemic resistance mechanism under pot culture experiments. Methodology: The selected native PPFMs were identified by analysis of 16S rRNA gene sequence. These isolates along with reference strain (Methylobacterium extorquens AM1) were inoculated to healthy chilli plants. The pathogen (Colletotrichum capsici) was later inoculated to these chilli plants, and induced systemic resistance (ISR) molecules were estimated at different intervals from one day after challenge inoculation of pathogen (DAI) upto 7 DAI. Influence of PPFM on plant growth parameters, yield, capsaicin content and PPFMs population load on phyllosphere and rhizosphere was studied. Results: The results of 16S rRNA gene sequence analysis revealed selected isolates as Methylobacterium populi (PPFM6) and Methylobacterium radiotolerans (PPFM170). The ISR molecules tested were significantly influenced by PPFM isolates. The peroxidase and phenyl alanine ammonia lyase (PALase) activity increased from 1 DAI to 7 DAI whereas chitinase, polyphenol oxidase (PPO) and phenol contents increased upto 5 DAI, after which gradual decrease was noticed. Inoculation of PPFMs to chilli crop significantly improved plant height, dry matter and chlorophyll content. Significantly lesser disease incidence, more yield and more capsaicin content was observed with application of M. populi as compared to control. Interpretation: The present study highlights native M. populi (PPFM6) of chilli as an effective plant growth promoter, exhibiting significant biocontrol efficiency against C. capsici.

Different wavelengths of visible light influence the conidial production and tolerance to ultra-violet radiation of the plant pathogens Colletotrichum acutatum and Fusarium fujikuroi

The effects of the visible light wavelengths on germination, mycelial radial growth, and conidial production of the plant pathogens Colletotrichum acutatum and Fusarium fujikuroi were studied. Both fungi were grown on potato dextrose agar medium (PDA) in the dark (control) or on PDA under continuous white, blue, green or red light. In addition, the conidia from each treatment were exposed to UV radiation. The germination and growth of both plant pathogenic fungi were not affected by any of the treatments. C. acutatum produced more conidia when the fungus grew under white and red light. F. fujikuroi produced more conidia in the dark. The tolerances to UV radiation of conidia produced on different light and dark treatments differed for both C. acutatum and F. fujikuroi. Conidia of C. acutatum were at least 30% more tolerant to UV radiation when they were produced under white light than under blue and green light and at least 20% more tolerant than conidia produced in the dark. Conidia of C. acutatum produced under red light were the least tolerant. Conidia of F. fujikuroi produced under white and blue light were at least 30% more UV tolerant than conidia produced in the dark, green, and red light. In conclusion, no differences were found for germination and growth for both fungi under different light regimes and dark; however, significant differences occurred both in production and UV radiation of conidia.

Genomic regions associated with resistance to anthracnose in the Guatemalan climbing bean (Phaseolus vulgaris L.) germplasm collection

The anthracnose disease caused by the fungal pathogen Colletotrichum lindemuthianum (Sacc & Magnus) Briosi & Cavara, is a disease that causes significant seed yield losses in common bean (Phaseolus vulgaris L.) worldwide. A germplasm collection of climbing beans from Guatemala was evaluated in the greenhouse for their reaction to race 73 of C. lindemuthianum that occurs in many growing areas worldwide. This germplasm mostly represents the so-called race Guatemala. Approximately 10% of 369 climbing bean accessions showed no symptoms (score of 1 on a 1–9 anthracnose severity visual score scale). Genome wide association study (GWAS) results using 78,754 SNP markers indicated that genomic regions with resistance to race 73 of C. lindemuthianum exist in Pv04 and Pv07, which have been previously reported. We also report four candidate genes located on Pv04 and Pv07 suspected to be responsible for anthracnose resistance, based on their proximity to significantly associated SNP markers.

Elucidating Anthracnose Resistance Mechanisms in Sorghum-A Review.

Sorghum (Sorghum bicolor) is the fifth most cultivated cereal crop in the world, traditionally providing food, feed, and fodder, but more recently also fermentable sugars for the production of renewable fuels and chemicals. The hemibiotrophic fungal pathogen Colletotrichum sublineola, the causal agent of anthracnose disease in sorghum, is prevalent in the warm and humid climates where much of the sorghum is cultivated and poses a serious threat to sorghum production. The use of anthracnose-resistant sorghum germplasm is the most environmentally and economically sustainable way to protect sorghum against this pathogen. Even though multiple anthracnose resistance loci have been mapped in diverse sorghum germplasm in recent years, the diversity in C. sublineola pathotypes at the local and regional levels means that these resistance genes are not equally effective in different areas of cultivation. This review summarizes the genetic and cytological data underlying sorghum's defense response and describes recent developments that will enable a better understanding of the interactions between sorghum and C. sublineola at the molecular level. This includes releases of the sorghum genome and the draft genome of C. sublineola, the use of next-generation sequencing technologies to identify gene expression networks activated in response to infection, and improvements in methodologies to validate resistance genes, notably virus-induced and transgenic gene silencing approaches.

Global mRNA and microRNA expression dynamics in response to anthracnose infection in sorghum

BackgroundAnthracnose is a damaging disease of sorghum caused by the fungal pathogen Colletotrichum sublineolum. Genome-wide mRNA and microRNA (miRNA) profiles of resistant and susceptible sorghum genotypes were studied to understand components of immune responses, and fungal induced miRNA and target gene networks.ResultsA total of 18 mRNA and 12 miRNA libraries from resistant and susceptible sorghum lines were sequenced prior to and after inoculation with C. sublineolum. Significant differences in transcriptomes of the susceptible and resistant genotypes were observed with dispersion distance and hierarchical cluster tree analyses. Of the total 33,032 genes predicted in the sorghum genome, 19,593 were induced by C. sublineolum, and 15,512 were differentially expressed (DEGs) between the two genotypes. The resistant line was marked by significant reprogramming of the transcriptome at 24 h post inoculation (hpi), and a decrease at 48 hpi, whereas the susceptible line displayed continued changes in gene expression concordant with elevated fungal growth in the susceptible genotype. DEGs encode proteins implicated in diverse functions including photosynthesis, synthesis of tetrapyrrole, carbohydrate and secondary metabolism, immune signaling, and chitin binding. Genes encoding immune receptors, MAPKs, pentatricopeptide repeat proteins, and WRKY transcription factors were induced in the resistant genotype. In a parallel miRNA profiling, the susceptible line displayed greater number of differentially expressed miRNAs than the resistant line indicative of a widespread suppression of gene expression. Interestingly, we found 75 miRNAs, including 36 novel miRNAs, which were differentially expressed in response to fungal inoculation. The expression of 50 miRNAs was significantly different between resistant and susceptible lines. Subsequently, for 35 differentially expressed miRNAs, the corresponding 149 target genes were identified. Expression of 56 target genes were significantly altered after inoculation, showing inverse expression with the corresponding miRNAs.ConclusionsWe provide insights into genome wide dynamics of mRNA and miRNA profiles, biological and cellular processes underlying host responses to fungal infection in sorghum. Resistance is correlated with early transcriptional reprogramming of genes in various pathways. Fungal induced genes, miRNAs and their targets with a potential function in host responses to anthracnose were identified, opening avenues for genetic dissection of resistance mechanisms.

A 3D Printed Device for Easy and Reliable Quantification of Fungal Chemotropic Growth.

Chemical gradients are surrounding living organisms in all habitats of life. Microorganisms, plants and animals have developed specific mechanisms to sense such gradients. Upon perception, chemical gradients can be categorized either as favorable, like nutrients or hormones, or as disadvantageous, resulting in a clear orientation toward the gradient and avoiding strategies, respectively. Being sessile organisms, fungi use chemical gradients for their orientation in the environment. Integration of this data enables them to successfully explore nutrient sources, identify probable plant or animal hosts, and to communicate during sexual reproduction or early colony development. We have developed a 3D printed device allowing a highly standardized, rapid and low-cost investigation of chemotropic growth processes in fungi. Since the 3D printed device is placed on a microscope slide, detailed microscopic investigations and documentation of the chemotropic process is possible. Using this device, we provide evidence that germlings derived from oval conidia of the hemibiotrophic plant pathogen Colletotrichum graminicola can sense gradients of glucose and reorient their growth toward the nutrient source. We describe in detail the method establishment, probable pitfalls, and provide the original program files for 3D printing to enable broad application of the 3D device in basic, agricultural, medical, and applied fungal science.

Fine mapping of an anthracnose-resistance locus in Andean common bean cultivar Amendoim Cavalo.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is one of the world’s most destructive diseases of common bean. The use of resistant cultivars is the most cost-effective strategy to manage this disease; however, durable resistance is difficult to achieve due to the vast virulence diversity of the anthracnose pathogen. Finding new genes with broad-spectrum resistance increases the prospect of designing an effective anthracnose-management strategy. Genetic analysis confirmed the presence of a single, dominant anthracnose-resistance locus in AC, which we provisionally named Co-AC. Bulk segregant analysis and genetic mapping of two F2 populations from the crosses AC × PI207262 and AC × G 2333 were used to determine the position of the Co-AC locus in a 631 Kbp genomic region flanked by the SNP markers SS56 and SS92 on the lower arm of chromosome Pv01. By genotyping 77 F3 plants from the AC × PI207262 cross using nine additional markers, we fine-mapped the Co-AC locus to a significantly smaller genomic region (9.4 Kbp) flanked by the SNP markers SS102 and SS165. This 9.4 Kbp region harbors three predicted genes based on the common bean reference genome, notably including the gene model Phvul.001G244300, which encodes Clathrin heavy chain 1, a protein that supports specific stomatal regulation functions and might play a role in plant defense signaling. Because the Co-AC resistance locus is linked in cis, it can be selected with great efficiency using molecular markers. These results will be very useful for breeding programs aimed at developing bean cultivars with anthracnose resistance using marker-assisted selection. This study revealed the broad-spectrum resistance of AC to C. lindemuthianum and the existence of the Co-AC anthracnose-resistance locus. Fine mapping positioned this locus in a small genomic region on the lower end of chromosome Pv01 that contained three candidate genes for the Co-AC locus.

Metabolites with phytopathogenic fungi inhibitory activities from the mangrove endophytic fungus Botryosphaeria ramose

To check whether the endophytic fungus from the host plant could produce novel bioactive metabolites induced by the host-derived chemical components, a strategy called “Induction of Endophyte Metabolism by Adding Host Components” (IEMAHC) was put up and applied. Cultivation of the endophytic fungus Botryosphaeria ramosa L29 derived from Myoporum bontioides after adding (2R, 3R)-3, 5, 7-trihydroxyflavanone 3-acetate, a constituent of the same plant, into the culture medium, led to the separation of three new chromones, 5-hydroxy-2, 3-dihydroxymethyl-7-methoxychromone (1), 5-hydroxy-3-acetoxymethyl-2-methyl-7- methoxychromone (2), 5, 7-dihydroxy-3-hydroxymethyl-2-methylchromone (3), one new isocoumarin, 8-hydroxy-3-hydroxymethyl-6-methoxy-7-methylisocoumarin (4), two new δ-lactones, botryopyrone (8) and (5S, 8R)-simplicilopyrone (9), one new naturally rare 2 (7H)-oxepinone, botroxepinone (10), and three known compounds (5–7). They were identified through comprehensive analysis of spectroscopic data. HPLC comparative analysis indicated that compounds 8–10 were induced products after adding (2R, 3R)-3, 5, 7-trihydroxyflavanone 3-acetate as an inducer. Compound 3 exhibited more potent inhibitory activities on Fusarium oxysporum, Fusarium graminearum, Penicillium italicum, and Colletotrichum musae than triadimefon. Compounds 1, 2, 4–7 and 9 displayed potent antifungal activities towards two or three tested fungi with MIC values equal or superior to triadimefon. The induced products 9 and 10 both showing strong inhibitory activity against C. musae, might play a role in strengthening the host defense against the common mangrove invasive pathogenic fungal genera Colletotrichum.

Sustainable Sugarcane Cultivation in India Through Threats of Red Rot by Varietal Management

Sugarcane is traditionally cultivated in India since time immemorial to extract gur and Khandsari sugar. In the country, white sugar manufacturing started ~ 300 years ago the with imported Saccharum officinarum genotypes. After 1850s, sugar industry expanded rapidly and such expansion also led to emergence of new threats in the form of red rot caused by the dreaded fungal pathogen Colletotrichum falcatum. The new threat caused production losses in the then Presidencies of Madras, Bombay and Bengal. Sugarcane Breeding Institute (SBI) was established in 1912 to breed sugarcane varieties for red rot resistance with other desirable agronomical traits. The institute achieved commercial success by releasing the first interspecific hybrid variety Co 205 during 1918 and release of many such varieties to the subtropical region revolutionized sugarcane cultivation by improved cane yield leading to attaining self-sufficiency in sugar requirement. Although the new varieties sustained the boom, red rot started attacking the elite varieties in different decades through a series of epidemics. These epidemics hindered sugarcane cultivation for a while in different states; however after each epidemic, new varieties were deployed to counter the disease onslaught and saved sugar industry from the brink. Many superior varieties with red rot resistance have benefitted the industry, but evolution of new C. falcatum pathotypes caused breakdown of resistance and made the life of many elite varieties short-lived. In the recent decades, variation in C. falcatum was characterized, designated into new pathotypes, and new pathotypes were used for red rot screening. The historical red rot epidemics in the country over the decades resembled to ‘boom and bust cycle’ reported in cereal rust diseases. Domination of single variety combined with flood during monsoon seasons/waterlogging favoured red rot epidemics. Notwithstanding red rot epidemics, red rot-resistant varieties played a vital role to manage the disease and to sustain sugarcane cultivation in India for more than 100 years.

Biocontrol potential of Streptomyces sp. CACIS-1.5CA against phytopathogenic fungi causing postharvest fruit diseases

BackgroundFungi are one of the microorganisms that cause most damage to fruits worldwide, affecting their quality and consumption. Chemical controls with pesticides are used to diminish postharvest losses of fruits. However, biological control with microorganisms or natural compounds is an increasing alternative to protect fruits and vegetables. In this study, the antifungal effect of Streptomyces sp. CACIS-1.5CA on phytopathogenic fungi that cause postharvest tropical fruit rot was investigated.Main bodyAntagonistic activity was evaluated in vitro by the dual confrontation over fungal isolates obtained from grape, mango, tomato, habanero pepper, papaya, sweet orange, and banana. The results showed that antagonistic activity of the isolate CACIS-1.5CA was similar to the commercial strain Streptomyces lydicus WYEC 108 against the pathogenic fungi Colletotrichum sp., Alternaria sp., Aspergillus sp., Botrytis sp., Rhizoctonia sp., and Rhizopus sp. with percentages ranging from 30 to 63%. The bioactive extract obtained from CACIS-1.5 showed a strong inhibition of fungal spore germination, with percentages ranging from 92 to 100%. Morphological effects as irregular membrane border, deformation, shrinkage, and collapsed conidia were observed on the conidia. Molecularly, the biosynthetic clusters of genes for the polyketide synthase (PKS) type I, PKS type II, and NRPS were detected in the genome of Streptomyces sp. CACIS-1.5CA.ConclusionsThis study presented a novel Streptomyces strain as a natural alternative to the use of synthetic fungicides or other commercial products having antagonistic microorganisms that were used in the postharvest control of phytopathogenic fungi affecting fruits.