Colletotrichum Gloeosporiodes Research Articles

Suppression of anthracnose disease by orsellinaldehyde isolated from the mushroom Coprinus comatus.

Anthracnose caused by Colletotrichum species is one of the most devastating diseases of fruits and crops. We isolated and identified an antifungal compound from the mushroom Coprinus comatus and investigated its inhibitory potential against anthracnose disease-causing fungi with the goal of discovering natural products that can suppress anthracnose-caused plant disease. The culture filtrate of C. comatus was subjected to a bioassay-guided isolation of antifungal compounds. The active compound was identified as orsellinaldehyde (2,4-dihydroxy-6-methylbenzaldehyde) based on mass spectroscopy and nuclear magnetic resonance analyses. Orsellinaldehyde displayed broad-spectrum inhibitory activity against different plant pathogenic fungi. Among the tested Colletotrichum species, it exhibited the lowest IC50 values on conidial germination and germ tube elongation of Colletotrichum orbiculare. The compound also showed remarkable inhibitory activity against Colletotrichum gloeosporiodes. The staining of Colletotrichum conidia with fluorescein diacetate and propidium iodide demonstrated that the compound is fungicidal. The postharvest in-vivo detached fruit assay indicated that orsellinaldehyde suppressed anthracnose lesion symptoms on mango and cucumber fruits caused by C. gloeosporioides and C. orbiculare, respectively. Orsellinaldehyde was identified as a potent antifungal compound from the culture filtrate of C. comatus. The inhibitory and fungicidal activities of orsellinaldehyde against different Colletotrichum species indicate its potential as a fungicide for protecting various fruits against anthracnose disease-causing fungi.

Influence of coloured lights on growth and enzyme production of beneficial endophytic fungi.

The influence of light regulation on fungal growth and enzyme production was tested on endophytic isolates of Fusarium proliferatum (CCH), Colletotrichum boninense (PL1, PL9, OL2), Colletotrichum gloeosporiodes (OL3) and Colletotrichum siamense (PL3). The isolates were treated with blue, red, green, and yellow light, while white fluorescent light (12h light/12h dark photoperiod) and 24h dark conditions were applied as control. Results revealed that coloured light treatments induced formation of circadian rings, while exposure to white light and dark conditions showed less pronounced circadian rings. Growth and sporulation of endophytes were not significantly influenced by light. By contrast, enzyme production was affected by coloured light treatments, notably with red (amylase), blue (cellulase) and yellow (cellulase, xylanase, L-asparaginase) light, resulting in lower enzyme levels for certain isolates. Under control conditions, enzyme production was relatively higher for amylase, cellulase, xylanase (for cultures incubated in the dark), and for L-asparaginase (for cultures incubated in white fluorescent light). Among the endophytic isolates, F. proliferatum (CCH) showed better response to coloured light treatment as higher sporulation and enzyme production was detected, although growth was significantly suppressed. On the contrary, C. gloeosporiodes (OL3) showed better growth but significantly lower enzyme production and sporulation when treated with the various coloured light. This study revealed that coloured light may have the potential to manipulate growth, sporulation and enzyme production in certain fungal species as strategies for fungal control or for harnessing of valuable enzymes.

Consortia of endophytic bacteria for controlling Colletotrichum gloeosporiodes causing anthracnose disease in chili plant

Abstract. Nurbailis, Yanti Y, Resti Z, Djamaan A, Rahayu SD. 2023. Consortia of endophytic bacteria for controlling Colletotrichum gloeosporiodes causing anthracnose disease in chili plant. Biodiversitas 24: 3503-3511. Anthracnose disease caused by Colletotrichum gloeosporioides is the main disease in chili plants, which reduces yields by up to 90%. Using a consortium of endophytic bacteria is an alternative way to control the disease at a low cost and is environmentally friendly. The aim of the study was to obtain the best consortium of endophytic bacteria to control anthracnose caused by C. gloeosporioides and improve the growth and yield of chili plants. This research was arranged in an experimental method consisting of two stages, namely (i) compatibility test between endophytic bacterial consisting of 28 species, and (ii) test of the endophytic bacterial consortium ability to control anthracnose in chili using a Completely Randomized Design (CRD) with 14 treatments and provided with 3 replications. All treatments of endophytic bacterial consortium showed the potential to suppress anthracnose disease caused by C. gloeosporioides and improve the growth and yield of chili plants. The best bacterial consortium treatment in suppressing the development of anthracnose disease by C. gloeosporioides and increasing the growth and yield of chili plants was the consortium B. cereus SNE 2.2 + B. cereus TLE 1.1 with dis-ease severity of 0.00%, plant height of 58.33 cm and fruit weight of 208.97 g.

Uji Beberapa Jamur Antagonis Terhadap Colletotrichum gloeosporiodes Penyebab Penyakit Busuk Buah Apel Manalagi (Malus sylvestris) Secara In Vitro

Colletotrichum Gloeosporiodes is one of the pathogenic fungi that causes fruit rot disease in apple plants. The control that has been widely used so far is chemical fungicides which cause negative effects, it is necessary to use an alternative control using antagonistic fungi that is safe and environmentally friendly. This study aims to determine the inhibition of several antagonistic fungi against the growth of the pathogen C. gloeosporiodes. The method used was a completely randomized design (CRD) with 4 types of antagonist fungi, 1 control and 5 replications. Antagonism test using dual culture method between antagonistic fungi Trichoderma harzianum, Trichoderma viridae, Trichoderma koningii, and Gliocladium sp. with C. gloeosporiodes. The test results showed that the antagonist fungus that had the highest percentage of inhibition against C. gloeosporiodes was T. harzianum at 87.8% and had a high inhibitory power category with a crude extract chitinase enzyme activity value of 4.30 U/mL and Gliocladium sp. has the lowest percentage of inhibition 64.3%. Based on these results, it can be concluded that T. harzianum has a high potential to control fruit rot disease in apples because it contains the chitinase enzyme which can degrade the cell wall of the pathogenic C. gloeosporiodes.

Management of Postharvest Anthracnose Disease of Papaya (Carica papaya) Using Antagonistic Microorganisms

The antagonistic potential of microbial agents isolated from different sources like compost, rhizosphere soil, healthy fruits surface were investigated against Colletotrichum gloeosporiodes under In vitro and In vivo. The results of In vitro evaluation of 22 isolates of antagonists against Colletotrichum gloeosporiodes by dual-culture test showed Trichoderma harzianum UHSF-15 (with 62.50% inhibition of radial growth), Bacillus amyloliquifaciens UHSB-BCA-15 isolated from banana rhizosphere soil (50.00% inhibition) and Bacillus amyloliquifaciensUHSB-BCA-16 isolated from kiwi fruit surface (47.85% inhibition) to be most effective. In vivo screening of five effective microbial agentsselected from In vitro studies revealed that, Bacillus amyloliquifaciens UHSB-BCA-15to be most effective with lowest per cent disease index of 13.89% followed by Bacillus amyloliquifaciensUHSB-BCA-16 with 16.67% and carbendazium at 0.1% with 20.83% at 9d after storage. The higher per cent disease index of 58.33% was recorded in untreated control fruits. In another experiment where C. gloeosporoidesspore suspension (1x106 CFU mL-1) was challenge inoculated on fruits, the fruits treated with biocontrol agent Bacillus amyloliquifaciens UHSB-BCA-15 at concentrations of 1x108 CFU mL-1 for 5 minutes was found to be effective in reducing postharvest infection to a greater level with 33.33% disease index followed by Bacillus amyloliquifaciens UHSB-BCA-16 with 50.00% disease index and carbendazium at 0.1% with 52.77% disease index compare to control (91.66% disease index) at 9d after storage.

Identification, Pathogenesis and Virulence Test of Fungus Causes Postharvest Disease of Gedong Gincu Mango from Pal Market, Cimanggis, Depok

Mango is a climacteric fruit that can increase in maturity after harvest. As a result, mangoes will rot more easily because they are infected with pathogens such as fungi. The objectives of the study were to identify, examine the pathogenicity, and virulence of the fungus that causes postharvest disease in mangoes. Sampling of mangoes was carried out at the Pal market, Cimanggis, Depok by selecting fruits that were indicated to be infected with post-harvest diseases. Symptoms that appear are then described visually. Isolation of the fungus was carried out from the part of the mango fruit on Potato Dextrose Agar (PDA) media, then it was identified morphologically both macroscopically and microscopically. The virulence test was carried out by inoculating the fungus at 4 inoculation points of mango fruit. The results showed that the symptoms that appeared were symptoms of anthracnose in the form of blackish brown, sunken, and widespread spots on the mango skin. The results of morphological identification showed that the associated fungus was Colletotrichum gloeosporiodes which was characterized by white fungal colonies and fast growth, while the condia were cylindrical in shape with rounded ends. Confirmation results with Koch's postulates showed that postharvest anthracnose in mangoes was caused by C. gloeosporiodes. Meanwhile, virulence testing showed that C. gloeosporiodes had moderate to high virulence levels with symptomatic lesions ranging from 2,50 to 5,85 cm.

Antagonistic and plant growth promotion effects of Mucor moelleri, a potential biocontrol agent

With the increasing demand for high quality and environmentally safe or green food, Biological Control Agents (BCAs) are playing critical roles in green agriculture, which in turn has paved the way for the requirement of effective, appropriate microbial antagonists. In this study, Mucor moelleri AA1 was isolated and investigated for its growth promotion and antagonism against Athelia rolfsii and Colletotrichum gloeosporiodes. The results showed a high antagonistic activity of M. moelleri against A. rolfsii and C. gloeosporiodes with percentage inhibitions of 73 % and 86 % respectively using the dual plate method, and the same antagonistic activity was also observed in liquid cocultures. A pot study analysis showed significant suppression of the diseases as well as growth promotion on tomato. Scanning electron microscopy (SEM) indicated that M. moelleri inhibited the growth of mycelium and the production of web-like materials. Based on headspace-solid phase microextraction (HS-SPME) analysis, microbial volatile compounds were determined, which were mainly aromatic compounds and alkaloids. Also, several antagonistic enzymes, such as β-1, 3- glucanase, proteases, catalase and ACC deaminase as well as the phytohormone IAA, were found to be produced by M. moelleri. Overall, these results combine to make M. moelleri a good prospective candidate for biological control and as a plant growth-promoting agent. The present study appears to be the first report identifying M. moelleri as a biological control agent.

Sodium silicate and chitosan: an alternative for the in vitro control of Colletotrichum gloeosporioides isolated from papaya (Carica papaya L.)

Colletotrichum gloeosporiodes is one of the main fungi that attacks tropical and subtropical fruits. In this study, sodium silicate and chitosan were applied individually and in conjunction at different concentrations to evaluate their efficacy in vitro on mycelial growth and on conidia sporulation. Besides, morphological changes on treated fungi were determined through scanning electron microscopy (SEM). Sodium silicate alone did not reduce C. gloeosporioides development, only a 9% inhibition was recorded. In contrast, chitosan treatments ranging from 0.1 to 1.5% showed the highest effectiveness and decreased fungal development the most (97 - 99%). However, the combined treatments showed an additive effect, by inhibiting the mycelial development between a 51 - 99%. SEM micrographs showed morphological alterations in the mycelium development, changes in size, and presence of deformations. Therefore, these treatments could be used as eco-friendly alternative in the control of C. gloeosporiodes in fruits.

Effectiveness of Organic Pesticides made from Cigarette Stub to the Attack Pest Intensity of Terminalia cattapa

The high consumption of cigarettes, especially in Indonesia, will produce harmful waste for the environment called cigarette stubs. The waste of cigarette stubs reacts with any kinds of pathogenic fungus such as Fusarium oxysporum, Colletotrichum gloeosporiodes, Rigidoporus lignosus, and Sclerotium rolfsii. The usage of cigarette stubs as an alternative raw material for making organic pesticides can make cigarette stubs considerable as a recycled product that reduces the environment's waste. The results obtained by plants treated with biopesticides effectively resist pest attacks and support plants to naturally develop antibodies. The score of Intensity Attack (IS) from Terminalia cattapa plant applied by the biopesticides for 10 days observation results in the amount of 3.953%, with a total of 34 normal leaves and a total of 12 broken leaves. The other result of the Terminalia cattapa applied with chemical pesticides gives 12.31% of intensity attack and 12.18% of intensity attack without any treatment. This research concluded that tobacco could inhibit the attack pest of the Terminalia cattapa plant.

A Natural Antifungal from Cassava Starch Fermentation Wastewater

Sour cassava starch production process, during the fermentation step, an acidic wastewater is generated, in this study named wastewater of cassava starch fermentation (WCSF). It has been studied the effect of WCSFs (from three industrial source: WCSF 1, 2 and 3) and patterns of organic acids (lactic, acetic, propionic and butyric acids, which were the main organic acids present in the WCSFs) singly or together on the development and growing of Botrytis cinerea, Monilinia fructicola and Colletotrichum gloeosporiodes. WCSFs showed antimicrobial effect on the three fungi studied. WCSF2 inhibited the germination of conidia from the three fungi, while WCSFs 1 and 3 inhibited conidia germination of B. cinerea and C. gloeosporiodes. The acetic, propionic, butyric and the mix acids were also effective in the reduction of conidial germination. In the analysis of mycelia growth, it has been observed that the growing was statically smaller, in relation to negative control, for all fungi in the treatments with the WCSFs and with the pattern solution of butyric acid. Which suggest that the WCSFs compounds and butyric acid are effective inhibitor for fungi and justify future studies using this wastewater.

Over expression of a Chitinase 2 gene from Chinese Wild Strawberry improves resistance to anthracnose disease in transgenic Arabidopsis thaliana

Strawberry (Fragaria × ananassa Duch.) is one of the most widely cultivated fruit crop. Anthracnose caused by Colletotrichum spp. is a devastating disease of strawberry, causing large-scale strawberry losses worldwide. Chitinases act as defence proteins and are crucial for plant response to pathogens. Here, we isolated a class V Chitinase gene (designed as FnCHIT2, GenBank accession number MN709779) from Chinese wild diploid strawberry Fragaria nilgerrensis Schlecht (F. nilgerrensis), a species that exhibits high tolerance to anthracnose. Gene expression analysis showed that FnCHIT2 expression was highly induced after Colletotrichum gloeosporiodes inoculation and salicylic acid (SA) treatment. Subcellular localization analysis revealed the presence of FnCHIT2 in the plasma membrane. Recombinant FnCHIT2 protein was successfully expressed in E. coli Rosetta (DE3). Furthermore, we transformed FnCHIT2 into Col-0 wild type A. thaliana to perform functional analysis and evaluated the functions of Colletotrichum higginsianum and Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). FnCHIT2 overexpression in A. thaliana showed enhanced resistance to C. higginsianum and Pst DC3000. Enhanced disease resistance of FnCHIT2 transgenic plants to C. higginsianum was correlated with pathogenesis-related gene 1 (AtPR1) and plant defensin 1.2 (AtPDF1.2) gene expression levels. These results provide evidence that FnCHIT2 may play an important role in response to fungal pathogens in strawberry. Our study provides an important theoretical reference for future strawberry resistance breeding.

Antagonistic Activity of Fungal Endophytes Isolated from Garcinia atroviridis against Colletotrichum gloeosporioides

The extensive use of synthetic fungicides in controlling plant disease generates detrimental impacts on the environment and human health. In response to this problem, an alternative method was developed, known as biological control using antagonistic microorganisms. Since investigation on fungal endophytes of Garcinia atroviridis is still unclear, it was chosen for the study. The aim of the present work was to evaluate biocontrol potential of endophytic fungi against Colletotrichum gloeosporiodes, a phytopathogen that caused anthracnose disease. A total of 92 endophytic fungi were isolated from different tissue parts of Garcinia atroviridis including leaves, petioles, branches, and fruits. Results demonstrated that, most of endophytic fungal isolates showed some inhibitory action over the growth of C. gloeosporiodes during dual culture growth. Endophyte isolate F14 showed the highest antagonistic activity against Colletotrichum gloeosporiodes with 67.38% percentage inhibition radial growth (PIRG). However, 7 out of 92 isolates showed no inhibitory effect against Colletotrichum gloeosporiodes. In conclusion, endophytic fungi isolated from G. atroviridis indicate the potential as biocontrol agents. It is hoped that the finding of isolated endophytic fungi in this study with antagonistic activity against anthracnose pathogen may be used in biocontrol programmes of plant disease in the region.

Antagonistic potential of soil fungi against Colletotrichum gloeosporiodes (Penz.) Sacc., the causal agent of anthracnose of Rauwolfia serpentina (L.) Benth. ex Kurz

Four antagonistic fungi Aspergillus flavus Link, A. fumigatus Fresenius, A. niger van Tiegh. and Trichoderma viride Pers. were isolated from field soil of Rauwolfia serpentina by serial dilution method and selected to evaluate their antagonistic potentiality against Colletotrichum gloeosporiodes (Penz.) Sacc, the causal agent of anthracnose of Rauwolfia serpentina (L.) Benth. ex Kurz following dual culture colony interaction, volatile and non-volatile metabolites. In dual culture method Trichoderma viride showed maximum (84.28%) inhibition of test fungi followed by Aspergillus niger (77.39%), A. fumigatus (43.71%) and A. flavus (29.32%). Volatile metabolites of T. viride showed higher (77.64%) inhibition of test fungi followed by A. flavus (75.58%), A. fumigatus (60.88%) and A. niger (58.23%). Non-volatile metabolites of antagonistic fungi showed that A. flavus showed (94.42%) inhibition of test fungus followed by T. viride (90.90%), A. niger (86.13%) and A. fumigatus (73.73%). Aspergillus flavus, A. niger and T. viride may be exploited commercially as a biocontrol agent against anthracnose disease of R. serpentina.
 Dhaka Univ. J. Biol. Sci. 28(2): 219-226, 2019 (July)

Efficacy of fungicides, bioagents and organic manure against Colletotrichum gloeosporiodes on Growth and Yield of Turmeric (Curcuma longa Linn.)

The field trials were conducted during 2015–2017, to determined individual and additive effect of two fungicides viz. Propiconazole and Carbendazim 12% and Manzozeb 63%, three bioagents viz. Trichoderma viride, T. harzianum & T. virens) and one organic manure i.e. neem cake on the growth, yield, leaf and rhizome pigments of turmeric against Colletotrichum gloeosporiodes causing leaf spot disease. Among all the foliar treatments, significant result (P  0.05) was recorded with propiconazole + Trichoderma viride + neem cake with growth parameters viz., plant height and rhizome girth (81.03 cm & 19.87 cm) and yield viz. fresh rhizome weight kg/plot and dry rhizome weight kg/plot (4.18 & 2.27) and chlorophyll 26.67mg/g of fresh leaf, carotenoid 0.850 mg/g of fresh leaf and % of curcumin 0.158 mg/g of fresh rhizome and with lower leaf spot incidence. The average of disease severity (17.65) over control (29.30). Neem cake gave least significant result at same parameters over the control. The results showed the significant increase in growth and yield with reduction of both leaf spot severity and incidence of turmeric over the control.

The Mitogen-Activated Protein Kinase CgMK1 Governs Appressorium Formation, Melanin Synthesis, and Plant Infection of Colletotrichum gloeosporioides.

The fungus Colletotrichum gloeosporiodes infects plant hosts with a specialized cell called an appressorium, which is melanized and required for plant cell wall penetration. Here, we show that the mitogen-activated protein kinase CgMK1 governs appressorium formation and virulence in the poplar anthracnose fungus C. gloeosporioides. Deletion of CgMK1 impairs aerial hyphal growth and biomass accumulation, and CgMK1 is responsible for the expression of melanin biosynthesis-associated genes. CgMK1 deletion mutants are unable to form appressorium and lose the capacity to colonize either wounded or unwounded poplar leaves, leading to loss of virulence. We demonstrate that the exogenous application of cAMP fails to restore defective appressorium formation in the CgMK1 deletion mutants, suggesting that CgMK1 may function downstream or independent of a cAMP-dependent signal for appressorium formation. Moreover, CgMK1 mutants were sensitive to high osmosis, indicating that CgMK1 plays an important role in stress response. We conclude that CgMK1 plays a vital role in regulating appressorium formation, melanin biosynthesis, and virulence in C. gloeosporiodes.

Thailandins A and B, New Polyene Macrolactone Compounds Isolated from Actinokineospora bangkokensis Strain 44EHW(T), Possessing Antifungal Activity against Anthracnose Fungi and Pathogenic Yeasts.

Two new polyene macrolactone antibiotics, thailandins A, 1, and B, 2, were isolated from the fermentation broth of rhizosphere soil-associated Actinokineospora bangkokensis strain 44EHW(T). The new compounds from this strain were purified using semipreparative HPLC and Sephadex LH-20 gel filtration while following an antifungal activity guided fractionation. Their structures were elucidated through spectroscopic techniques including UV, HR-ESI-MS, and NMR. These compounds demonstrated broad spectrum antifungal activity against fungi causing anthracnose disease (Colletotrichum gloeosporioides DoA d0762, Colletotrichum gloeosporiodes DoA c1060, and Colletotrichum capsici DoA c1511) as well as pathogenic yeasts (Candida albicans MT 2013/1, Candida parasilopsis DKMU 434, and Cryptococcus neoformans MT 2013/2) with minimum inhibitory concentrations ranging between 16 and 32 μg/mL. This is the first report of polyene antibiotics produced by Actinokineospora species as bioactive compounds against anthracnose fungi and pathogenic yeast strains.

English

The study aimed to evaluate the chemical composition and the fungitoxicity of Cymbopogon citratus (DC) Staf essential oil, obtained in different seasons of the year. Therefore, C. citratus leaves were harvest at four seasons (summer, fall, winter and spring) and essential oil extracted by hydrodistillation of freshly harvested and dried leaves, with a total of eight samples. Yield was expressed in percentage and the fungitoxicity was evaluated in vitro on Colletotrichum gloeosporiodes (Penz.) Penz. & Sacc the causal agent of anthracnose at different concentrations (0, 0.25, 0.5, 0.75 and 1 µL mL-1, respectively). The qualitative analysis of essential oil samples was made using gas chromatography coupled to mass spectrometry (GC-MS). The essential oil of freshly harvested leaves had a higher yield (0.25%) in the summer, whereas the essential oil of dried leaves had a better yield (0.48%) in the fall. In in vitro tests, concentrations of 0.75 and 1 µL mL-1 significantly inhibited mycelial growth and sporulation, in all samples. In the quantitative analysis, there was a variation in the levels of oil compounds observed in the different seasons. The most abundant compound in essential oil was citral (neral and geranial mixture) and myrcene. However, the variation in the compounds’ levels had no influence on the fungitoxicity of C. gloeosporiodes (Penz.) Penz. & Sacc. Key words: Lemongrass, citral, anthracnose, seasons, yield.

Metabolomics Analysis on Antifungal Activities Produced by Penicillium oxalicum T3.3 Grown on Different Types of Carbon Sources

Anthracnose is a disease caused by a fungal Colletotrichum gleosporioides. It is a common disease to dragon fruit plant and has caused a great loss to this industry. This pathogenic fungus can cause damage to most parts of plants including roots, stems, leaves, flowers and fruits. One of the potential microorganisms that able to produce antimicrobial activity against this plant pathogen is the endophytic fungus. However, research carried out on metabolomics of cellular metabolites produced by endophytic Penicillium oxalicum against C. gleosporioides is very limited. Thus, this study was conducted with the aims to evaluate the antifungal activities produced by Penicillium oxalicum T3.3 against Colletotrichum gloeosporiodes by using different types of carbon sources in fermentation medium and to identify the possible compounds produced by this strain through metabolomics approach. Preliminary study on locally isolated; P. oxalicum T3.3 had shown a promising antagonism through antifungal secondary metabolites which suppressed the growth of C. gloeosporioides. Disc diffusion test was conducted in order to determine the inhibition zone on the growth of C. gloeosproides. Among the six carbon sources tested, glucose exhibited the highest percent inhibition of radial growth (PIRG) of 75% and producing inhibition zone ranges from 4 to 7 mm. The minimum inhibition concentration (MIC) and minimum fungicidal concentration (MFC) of the glucose crude extract was the highest with 78 μg/mL and 2500 μg/mL, respectively. Meanwhile, starch and xylitol crude extracts gave the lowest MIC value of 1250 μg/mL and no MFC can be recorded. The compounds were extracted with ethyl acetate and 1H NMR analysis was carried out to identify candidate compounds that had been produced. Metabolomics studies were conducted by analyzing the spectrum using SIMCA P+, Principal Component Analysis (PCA) and Partial Least Square (PLS) multivariate statistical method. The conducted metabolomics study showed that sugar crude extracts (glucose, sucrose and maltose) tend to produce more threonine, 2-heptanone, lactate, valine, butyrate, O-phosphoserine. Meanwhile complex sugar substrates (xylitol, starch and Undaria pinnatifida) produced more acetic acid, methionine and leucine. From this analysis, different metabolites produced by P. oxalicum T3.3 were clustered according to the carbon sources used. This research demonstrates the potential of using a combination of 1H NMR spectroscopy and multivariate data analyses in differentiating the effect of carbon sources used based on the identification of possible metabolites contributing to their differences.

Ulvan effect on conidial germination and appressoria formation of Colletotrichum gloeosporioides

Ulvan is an algal polysaccharide known for its ability to induce resistance to plant diseases such as the Glomerella leaf spot of apple caused by Colletotrichum gloeosporiodes. This study was aimed at investigating microscopically, in tests in vitro and in vivo, whether ulvan interferes in the development of pre-infective structures of C. gloeosporioides. Conidial germination and appressoria formation were monitored hourly on agar and cellophane, and at 48 h on water- and ulvan-treated susceptible as well as resistant apple leaves. Amendment of agar with ulvan (10 mg ml−1) enhanced the germination and resulted in longer germ tubes at 7 h of incubation. On cellophane it significantly delayed appressoria formation up to 8 h, but later after 14 h increased the number of appressoria per conidium. Spraying of susceptible leaves with ulvan 6 days before inoculation decreased disease severity by 50%. This was associated with inhibition of appressoria formation and stimulus in growth of germ tubes, without interfering with conidial germination, when compared with both water-treated control and resistant plants. Appressorium formation occurred preferentially on anticlinal walls of epidermal cells and its location was not influenced by host resistance or by ulvan treatment. This study suggests a new mode of action for ulvan interfering with appressorium formation that could protect apple plants against C. gloeosporioides infection.

Perlakuan Udara Panas sebagai Tindakan Karantina terhadap Biji Kedelai

Introduction and dissemination of plant disease agents can be avoided through physical treatment on agricultural commodities as pre and post harvest treatment. Research was conducted to find effective quarantine treatment to eradicate fungi infestation on soybean seed. Four fungi species were chosen for this study, i.e. Cercospora sp., Sclerotium rolfsii, Colletotrichum gloeosporiodes, and Pestalotia sp. The evaluation was conducted for seed, seedling, bean oilcake, and fungi culture using hot air treatment on 45, 50, 55, 60, 65, 70 °C and control for 5 h. In general, heat treatment caused suppression significantly on seed germination and seedling growth. However, heat treatment on 45, 50 and 55 °C resulted on lower infestation of fungi on seed, and no infestation was observed on 65 and 70 °CKey words: eradication, quarantine treatment, heat treatment