​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.

First report of blast of durum wheat in Bangladesh, caused by Magnaporthe oryzae pathotype Triticum

Durum wheat (Triticum turgidum var. durum Desf.) is an important cereal crop in many regions of the world. In March of 2018 and 2019, symptoms typical of blast were frequently observed on durum wheat plants under field conditions in Jashore, Bangladesh. The putative causal pathogen was isolated from infected wheat spike specimens onto potato dextrose agar and oatmeal agar, and was identified from mono-conidium cultures as Magnaporthe oryzae, based on morphological features. The pathotype of the fungus was identified as Triticum, based on comparative molecular analyses of ITS sequences and MoT3 specific markers. BLAST analysis revealed >99.8% similarity with M. oryzae/P. oryzae, retrieved from the NCBI Genebank. This was confirmed through amplification of the predicted products with MoT3 primers in PCR analysis. Pathogenicity was confirmed by inoculating healthy durum wheat seedling leaves and spikes with a conidium suspensions of M. oryzae isolate DuBWMRI1901.2A. The fungus produced similar symptoms on inoculated leaves and spikes as those observed in the field, and was subsequently re-isolated, fulfilling Koch’s postulates. This is the first report of blast of durum wheat caused by Magnaporthe oryzae pathotype Triticum in Bangladesh.

A Simple and Effective Technique for Production of Pycnidia and Pycnidiospores by Macrophomina phaseolina

Production of pycnidia and pycnidiospores by Macrophomina phaseolina is not often seen in vitro. The objective of this study is to develop a simple and effective technique to obtain pycnidiospores of M. phaseolina isolates in vitro and to evaluate germination rates and pathogenicity of pycnidiospores. We found M. phaseolina isolates can produce pycnidia on oatmeal agar (OMA) under ultraviolet light with 365 nm wavelength (UV). For evaluating the effect of OMA and UV on growth of M. phaseolina, combinations of two agar media and three lighting conditions were tested. The results confirm that all six M. phaseolina isolates produced pycnidia only on OMA under UV. The pycnidiospores produced on OMA under UV had germination rates higher than 90%. In pathogenicity tests, inoculation with the pycnidiospores showed symptoms later than inoculation with hypha-colonized toothpicks. Significant differences in the pathogenicity is detected between isolates Mp2014003 and Mp2014024 when inoculation is done with the pycnidiospores (P < 0.001), but not when hypha-colonized toothpicks are used as inoculum (P = 0.091). This study provides a new method for obtaining pycnidiospores of M. phaseolina for future investigations.

Бактерии в гифосфере Phytophthora infestans и Alternaria alternata на картофеле

Фитофтороз и альтернариоз, вызываемые фитопатогенами Phytophthora infestans (Mont.) de Bary и Alternaria alternata (Fr.) Keissl., опаснейшие болезни картофеля и томата. Бактериозы картофеля другая опасная проблема как картофеля и томата, так и других с.-х. культур. Нередко возбудители бактериозов, особенно пектолитические бактерии, присутствуют на пораженных растениях вместе с фитопатогенными псевдогрибами и грибами, в том числе с Ph. infestans и A. alternata. Цель исследования оценить присутствие бактерий в гифосфере Phytophthora infestans и Alternaria alternata, а также влияние бактерий на характеристики Ph. infestans и A. alternata. Лабораторные исследования проводили в лаборатории сектора фитопатологии кафедры защиты растений в 2016-2019 годах. Использовали изоляты Ph. infestans T-9, IO-37, 161, A. alternatа Д12 из коллекций МГУ имени М. В. Ломоносова и РГАУ-МСХА имени К. А. Тимирязева. Заражение дисков клубней картофеля сортов Жуковский ранний, Ред Скарлетт, Сарпо Мира, Луговской, Удача проводили в марте 2016 года на фоне потепления погодных условий, температура в лаборатории достигала 25 С. Наличие бактерий в мицелиях исследуемых штаммов Ph. infestans, выращиваемых на овсяном агаре, проверялили посредством световой и электронной микроскопии, а также путем смывов с мицелиев и высевом на специальные питательные среды King B и YDS. В результате исследований доказано наличие пектолитических бактерий в гифосфере Ph. infestans и A. alternatа. При наличии бактерий доказаны лизис и изменения морфологии Ph. infestans и конкурентная экспрессия по локусам глюкозо-6 фосфат изомеразы (Gpi-1) и малатдегидрогеназы (Mdh-2). Инокуляция клубневых дисков четырех сортов картофеля Жуковский ранний, Ред Скарлетт, Сарпо Мира и Удача суспензиями патогенов на фоне повышенной температуры выявили значительное развитие бактериозов уже на первые сутки инкубации. Только на сорте Луговской развитие данные симптомов было в значительной степени подавлено. Мицелии Ph. infestans, A. alternata и пектолитические бактерии их гифосферы образуют на картофеле единый и достаточно стабильный патокомплекс с достаточно сложными взаимосвязями, которые предстоит изучать. Этот патокомплекс способен создать напряженный комбинированный инфекционный фон на картофеле, который в ряде случаев способен представлять для него существенную опасность.Late blight and early blight caused with phytopathogens Phytophthora infestans (Mont.) de Bary and Alternaria alternata (Fr.) Keissl. are the dangerous diseases of potato and tomato. Bacteria are connected to the other dangerous problems of both potato and tomato, and other crops. Often bacteria especially pectolytic bacteria occur on affected plants with phytopathogeneous pseudofungi and fungi with Ph. infestans и A. alternata as well. Objective of our investigation is an estimation of bacterial occurrence in Ph. infestans and A. alternata hyphosphaere as well as influence of bacteria on the Ph. infestans and A. alternate properties. Laboratory investigations were conducted at phytopathology branch of department of plant protection of RSAUMTAA in 2016-2019. Ph. infestans isolates T-9, IO-37, 161, A. alternatа isolate D12 of MSU and RSAUMTAA were investigated. Tuber disc inoculation of potato cultivars Zhukovskiy ranniy, Red Scarlett, Sarpo Mira, Lugovskoy and Udacha was done in 2016 at the temperature about 25 C. Checking bacterial occurrence was done in Ph. infestans mycelia grown at oatmeal agar by means of light and electronic microscopy as well as with transferring on special selective media King B and YDS. As a result, occurrence of pectolytic bacteria was proved to be in Ph. infestans and A. alternatа hyphosphaere. At bacterial occurrence Ph. infestans lysis and morphological deviations as well as competitive expression at the loci of Glucose 6 Phosphate Isomerase (Gpi-1) and Malate Dehydrogenase (Mdh-2) are proved to be developed. Inoculation of potato tuber discs of five cultivars Zhukovskiy ranniy, Red Scarlett, Sarpo Mira and Udacha with suspensions of pathogens at increased temperature revealed essential bacterial development at increased temperature during already first day of incubation. Manifestation of these symptoms was significantly suppressed only on cultivar Lugovskoy. Ph. infestans and A. alternata mycelia as well as pectolytic bacteria of their hyphosphaere form on potato unique and stable pathocomplex with complicated interconnections which should be studied as quickly as possible. This pathocomplex provides strong combined infective phone on potato which is able to be essentially dangerous for this crop.

Seed germination and development of orchid seedlings (Cyrtopodium saintlegerianum) with fungi

Fungi of Rhizoctonia complex are mycorrhizal of orchids and may to germinate yours seeds and development the seedlings. In this context, our objective was to select a fungal isolate to promote seed germination and seedling development of Cyrtopodium saintlegerianum. Pelotons were found in the roots and three mycorrhizal fungi were isolated. We tested mycorrhizal isolates obtained from C. saintlegerianum roots and six mycorrhizal fungi from other orchids as well three pathogenic isolates (of rice and bean) to germinate the seeds in oatmeal-agar medium. Seeds not inoculated were used as control. The isolates En07 (Waitea circinata), Cs10 (Tulasnella sp.) and Ro88 (Rhizoctonia oryzae) were efficient to promote seed germination, but only En07 differing statistically of the control. The non-specific isolate En07 promoted germination in 81% of seeds and the specific isolate (Cs10) promoted 60%, evidencing the non-specificity mycorrhizal association in this orchid during germination. Axenic seedlings were inoculated with four mycorrhizal fungi (non-inoculated seedlings - control). After six months, the isolates En07 and Cs10 were efficient in the interaction with the seedlings, but did not differ to the control. Therefore, our results suggested that fungi of the Rhizoctonia complex can be used in the germination and seedling development of C. saintlegerianum.

Morphological Characteristics and Genetic Variability of Trichoderma spp. From Conventional Cotton Crop Soils in Federal District, Brazil

This study aimed to characterize 41 isolates of Trichoderma from conventional cotton crops soils as the morphological and cultural characteristics and to investigate polymorphism, using RAPD markers. The most common group comprised 80.6% of the isolates and was identified as a strain of Trichoderma harzianum. The others species were T. aureoviride (7.3%), T. viride (7.3%) and T. crassum (4.8%). The four species were morphologically distinct in the evaluated characteristics such as colony appearance and mycelium growth rate after being grown on malt extract agar (MEA), potato dextrose agar (PDA) and oatmeal agar (OA) media, and also in shape of conidia, phialides, and conidiophores. The four species were separated in a dendogram, after using RAPD markers. Besides, RAPD was efficient in demonstrating the high intraspecific genetic variation among isolates of two species (T. harzianum and T. aureoviride).

Isolasidan Karakterisasi Morfologi Aktinomiset Indigenus Asal Tanah Gambut

Aktinomiset merupakan kelompok mikroorganisme yang tersebar luas di lingkungan darat, air tawar dan laut. Aktinomiset memainkan peran penting dalam dekomposisi bahan organik dan dengan demikian mengisi pasokan nutrisi dalam tanah.Penelitian ini bertujuan untuk mengisolasi dan karakterisasi morfologi aktinomiset indigenus asal tanah gambut. Isolasi aktinomiset dari contoh tanah gambut yang memiliki karakteristik pH 4.7, rasio C/N 38 dan nilai KTK 70.5 asal Tanjung Jabung Barat, Jambi.Isolat yang diperoleh dimurnikan dan diremajakan kembali pada media Yeast Malt Agar (YMA). Isolat aktinomiset yang telah murni ditumbuhkan pada tiga jenis media pertumbuhan yaitu Yeast Malt Agar (YMA), Yeast Starch Agar (YSA), dan Oatmeal Agar (OM) selama ±10 hari pada suhu ruang. Selanjutnya, dilakukan pengelompokan isolat aktinomiset berdasarkan warna koloninya. Terdapat 80 koloni aktinomiset yang berhasil diisolasi dari contoh tanah gambut, yang tumbuh pada media agar-agar HV dan dimurnikan di media YMA. Hasil seleksi berdasarkan keragaman bentuk koloni dari 80 isolat diperoleh 20 isolat murni yang memiliki beragam morfologi koloni, menghasilkan miselia aerial dan mampu tumbuh baik serta bersporulasi pada umur 7-14 hari. Karakteristik morfologi ini mengindikasikan isolat-isolat tersebut adalah Streptomyces sp.

OPTIMISATION OF GROWING CONDITIONS OF EUROPEAN MISTLETOE HYPERPARASITIC FUNGUS (PHAEOBOTRYOSPHAERIA VISCI): EFFECT OF DIFFERENT MEDIA AND ANTIBIOTICS / OPTIMALIZÁCIA RASTOVÝCH PODMIENOK PHAEOBOTRYOSPHAERIA VISCI, HYPERPARAZITICKEJ HUBY IMELA BIELEHO: VPLYV RÔZNYCH ŽIVNÝCH MÉDIÍ A ANTIBIOTÍK

European mistletoe (Viscum album) is an evergreen, perennial, hemiparasitic shrub, which is able to infect more than 450 woody species. Besides mechanical pruning, a hyperparasitic fungus (Phaeobotryosphaeria visci) could be a successful candidate to develop an effective biocontrol agent against mistletoe. It was necessary to find antibiotics which make the isolation easier and do not effect mycelia growth negatively under strain. Furthermore, we wanted to define a medium for optimal growth under in vitro laboratory conditions. Three different media (potato-dextrose agar, modified oatmeal agar, ¼ PDA + V8 agar) and four antibiotics (kanamycin, ampicillin, rifampicin, nystatin) were tested. Oatmeal agar and potato-dextrose agar are optimal to maintain the fungal strains, the colony diameter was 9 cm on the 12th day. All tested antibiotics are useful, except nystatin.