Aktivitas Sitotoksik dan Antibakteri Ekstrak Etil Asetat Jamur Endofitik Colletotrichum gloeosporioides

Artocarpus heterophyllus merupakan salah satu tumbuhan yang dilaporkan menghasilkan beragam senyawa yang bersifat sitotoksik dan antibakteri. Selain melakukan studi kimia terhadap tumbuhan alaminya, eksplorasi terkait kajian fitokimia tumbuhan ini dapat dilakukan terhadap jamur endofitik yang berkolonisasi dengan tumbuhan A. heterophyllus. Tujuan penelitian ini adalah melakukan uji aktivitas antibakteri dan sitotoksik ekstrak EtOAC jamur endofitik yang berkolonisasi dengan daun A. heterophyllus. Tahapan dari penelitian ini terdiri dari inokulasi, sub-kultur, kultivasi jamur endofitik yang dilanjutkan dengan ekstraksi, uji aktivitas biologi dan uji kandungan kimia dari ekstrak etil asetat jamur Colletotrichum gloeosporioides yang diisolasi dari daun A. heterophyllus. Hasil uji sitotoksik menunjukkan bahwa ekstrak EtOAc jamur bersifat aktif terhadap sel murin leukemia P-388 dengan nilai IC50 18,97 µg/mL. Hasil uji antibakteri juga menunjukkan bahwa ekstrak EtOAc mempunyai kemampuan dalam menghambat pertumbuhan keempat bakteri uji dengan rentang zona hambat 4,3 – 14,3 mm. Untuk infomasi bagi kita semua bahwa penelitian terkait kajian sifat antibakteri dan sitotoksik dari jamur yang hidup pada daun A. heterophyllus baru pertama kali dilakukan pada kesempatan ini.

Development of Molecular Marker to Detect Citrus Melanose Caused by Diaporthe citri from Citrus Melanose-like Symptoms

It is difficult to distinguish melanose and melanoses-like symptoms with the naked eye because they appear similar. To accurately detect melanose symptoms caused by Diaporthe citri from melanose-like symptoms, we developed PCR-based specific primers Dcitri by aligning the internal transcribed spacer (ITS) region of D. citri with the ITS of Diaporthe cytosporella, Diaporthe foeniculina, Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria citri, and Fusarium oxysporum found on citrus peel. PCR results showed that the specific product was amplified in D. citri but not in other isolates including, C. gloeosporioides, B. cinerea, A. citri, F. oxysporum. In addition, specific products were observed in melanose symptoms caused by D. citri but not in melanose-like symptoms, such as copper-injury, sunscald, damages by yellow tea thrips, and pink citrus rust mite. Using the Dcitri primers developed in this study, it is expected that melanose caused by D. citri could be accurately distinguished from melanose-like symptoms.

Evaluasi Cendawan Endofit Asal Tanaman Karet untuk Mengendalikan Colletotrichum gloeosporioides Patogen Penyakit Gugur Daun Colletotrichum

<p><em>Colletotrichum leaf fall disease caused by </em>Colletotrichum gloeosporioides<em> is an important disease in rubber plants. The </em>C. gloeosporioides<strong><em> </em></strong><em>Infection can reduce production by 7%-45%. Controlling the pathogen using endophytic fungi is very promising because it can suppress inoculum and pathogen colonization, induce plant resistance, and trigger plant growth. The study aimed to evaluate the endophytic fungus isolate from rubber to control </em>C. gloeosporioides<strong><em> </em></strong><em>as a pathogen that caused the rubber leaf fall disease. This research was carried out in the laboratory and greenhouse of the Indonesian Industrial and Beverage Crop Research Institute (IIBCRI), Sukabumi, from March to November 2018. The isolates used were endophytic fungi isolates from rubber plants, which were tested for their inhibition against </em>C. gloeosporioides<em> in vitro on rubber leaves and seedlings, and their mechanism. The variable observed were the inhibition rate, incubation periods, number of spots, disease severity, and plant growth. The results showed that the endophytic fungus could inhibit the growth of </em>C. gloeosporioides<em> about 64.17% - 86.67%. The high inhibitory activity (&gt;80%) in isolates CEPR.19, CEPR.6, CEBPM.21, DTJE.1, and DMJE27 were 86.67%; 83.33%; 83.33%; 82.92%, and 82.50%, respectively. The observations on seedlings obtained three potential fungal isolates to control </em>C. gloeosporioides<em> on rubber leaves, namely CEBPM.21, CEPR19, and DTJE.1 with suppression of disease severity about 68.57%; 67.88%, and 60.20% with their mechanisms of action inducing resistance, antibiosis, competition, and hyperparasites.</em><em></em></p>

​In-vitro Effect of Different Abiotic Stresses on the Growth and Sporulation of Colletotrichum gloeosporioides causing Anthracnose of Mango

Background: Mango productivity was very much affected due to a major fungal pathogen, Colletotrichum gloeosporioides causing anthracnose mango rot. The present study was carried out to investigate the influence of abiotic factors for the support of superficial growth of isolated fungus and finding a minimum inhibitory concentration of different fungicides. Methods: Among four different culture media tested, the highest radial growth and sporulation of the fungus were recorded in Oatmeal agar (OMA) (84 mm) followed by Conn’s agar (CA), Czapek Dox agar (CDA) and Potato dextrose agar (PDA). Among the different pH tested, pH 7.0 was found to be the best in supporting the good radial growth (69 mm) followed by pH 6.0 (56 mm), pH 5.5 (49 mm), pH 7.5 (43 mm) and pH 8.0 (37 mm). Among the various temperature tested, 25oC (69.32) was found to be the best followed by 20oC (52.53 mm), 30oC (65.23 mm) and 35oC. Result: Among the fungicides tested, Zineb 68% + Hexaconazole 4% WP (avtar) was found best as the radial growth was observed to be 45, 41, 36, 32, 25 mm at 5, 10, 25, 50 and 100 ppm, respectively as compared to 80 mm in control. The fungicide Tricyclazole 18% + Mancozeb 62% WP (Merger) was found to be the least effective in checking the radial growth of C. gloeosporioides even at 100 ppm concentration.

Distinct Transcriptional Programs Underlie Differences in Virulence of Isolates on Host Plants in a Fungal Pathogen, Colletotrichum gloeosporioides

Susceptible host plants challenged by fungal pathogens can display different types of lesions, which can be attributed to environmental factors affecting the nature of interactions between the host and pathogen. During our survey of apple anthracnose in Korea, two distinct types of disease symptoms, designated as progressive (PS) and static symptoms (SS), were recognized. PS is a typical, rapidly enlarging symptom of apple anthracnose, while SS is a small, dark speck that does not expand further until the harvesting season. Isolation and genotyping of pathogens from disease lesions suggested that all of them belong to Colletotrichum gloeosporioides, a well-known causal agent of apple anthracnose. Two types of isolates were comparable in growth on media, spore germination and appressorium formation, virulence test on fruits at various temperature conditions. Furthermore, they were analyzed at the molecular level by a phylogenetic tree, RNA-seq, and expression of virulence gene. However, the SS isolates were defective in appressorium-mediated penetration into the underlying substratum. RNA-seq analysis of PS and SS isolates showed that distinct transcriptional programs underlie the development of different types of anthracnose symptoms in host plants. One downregulated gene in SS encoded isocitrate lyase is essential for disease development via its involvement in the glyoxylate cycle. It partly explains why SS is less virulent than PS on host plants. Overall, our work challenges the traditional view on the development of different lesion types and provides valuable insights into variations that exist in the pathogen population.

Fungal Pathogens Associated with Damping-off Disease of Cashew Seedlings in Nigeria

Aim: This study was designed to isolate fungal pathogens associated with damping-off of cashew seedlings. Study Design: The cashew seedlings for this study were selected randomly from a number of infected cashew seedlings in the screen house. Methodology: Associated fungal pathogens were grown on potato dextrose agar (PDA) and identified using their characteristics and morphological features observed under the microscope with reference to published identification manuals. Results: The result showed that damping-off of cashew seedling is mostly associated with fungal pathogens such as such as Fusarium spp, Colletotrichum gloeosporioides, Pythium spp., Alternaria sp., Curvularia sp., Aspergillus niger, and Lasiodiplodia theobromae. However, Fusarium spp, and Pythium spp. were predominant and frequently isolated than other pathogens. Conclusion: The knowledge of these pathogens is important for designing strategies to safeguard cashew plant health against diseases in order to ensure sustainable cashew production in Nigeria.

Antifungal Activity of Essential Oils from Three Artemisia Species against Colletotrichum gloeosporioides of Mango

Post-harvest diseases of mango reduce fruit quality and cause severe yield losses with completely unmarketable fruits. The most common diseases of mangos are anthracnose (Colletotrichum gloeosporioides). In this study, the antibacterial activities of essential oils from Artemisia scoparia, Artemisia lavandulaefolia, and Artemisia annua against C. gloeosporioides were tested. The results showed that the essential oil of A. scoparia was more effective by the agar diffusion method; the EC50 value was 9.32 µL/mL. The inhibition rate was 100%, at a concentration of 10 μL/mL, through the spore germination method. The morphological changes of the mycelium were observed by scanning electron microscopy (SEM), the mycelia treated with essential oils showed shrinking, deformity, fracture, and dryness through SEM. A. scoparia essential oil was inoculated in vivo and subjected to paroxysm testing under natural conditions. A. scoparia had significantly inhibitory activity, and the inhibition rate was 66.23% in vivo inoculation tests after 10 days. The inhibition rate was 92.06% in the paroxysm test under natural conditions after 15 days. Finally, A. acoparia essential oil was analyzed by gas chromatography-mass spectrometry. The main compounds were 2-ethenyl-Naphthalene (23.5%), 2,4-pentadiynyl-Benzene (11.8%), 1,2-dimethoxy-4-(2-propenyl)-Benzene (10.0%), β-Pinene (8.0%), and 1-methyl-4-(1-methylethyl)-1,4-Cyclohexadiene (6.3%). The results have revealed the potential use of A. scoparia essential oil against post-harvest fungal pathogens C. gloeosporioides.