Endophytic Colletotrichum species from Dendrobium spp. in China and Northern Thailand

Species of Colletotrichum are commonly found in many plant hosts as pathogens, endophytes and occasionally saprobes. Twenty-two Colletotrichum strains were isolated from three Dendrobium species – D.cariniferum, D.catenatum and D.harveyanum, as well as three unidentified species. The taxa were identified using morphological characterisation and phylogenetic analyses of ITS, GAPDH, ACT and ß–tubulin sequence data. This is the first time to identify endophytic fungi from Dendrobium orchids using the above method. The known species, Colletotrichumboninense, C.camelliae-japonicae, C.fructicola, C.jiangxiense and C.orchidophilum were identified as fungal endophytes of Dendrobium spp., along with the new species, C.cariniferi, C.chiangraiense, C.doitungense, C.parallelophorum and C.watphraense, which are introduced in this paper. One strain is recorded as an unidentified species. Corn meal agar is recommended as a good sporulation medium for Colletotrichum species. This is the first report of fungal endophytes associated with Dendrobiumcariniferum and D.harveyanum. Colletotrichumcamelliae-japonicae, C.jiangxiense, and C.orchidophilum are new host records for Thailand.

Effect of different nutrient media on radial growth of Alternaria brassicae (Berk.) Sacc. infecting different Brassica host crops

Alternaria brassicae (Berk.) Sacc. is the most common and destructive pathogen of a number of Brassica crops belong to family Brassicaceae. It has been reported from all the continent of the world and causes considerable losses in terms of quality and quantity of crop produce. The present investigation was undertaken in vitro, to know the effect of different nutrient media viz., Potato Dextrose Agar (PDA), V-8 Juice Agar (V8JA), Richard’s Agar (RA), Czapeck’s Dox Agar (CDA) and Corn Meal Agar (CMA) on the growth of A. brassicae isolates collected from the different Brassica host crops i.e. Mustard, Cauliflower, Cabbage and Radish. These isolates were designated on the basis of their hosts as Acae M, Acae Cf, Acae Ca and Acae R, respectively. Radial growth of all isolates was observed after seven days of incubation. The result showed a marked variation in radial growth of A. brassicae isolates. However, maximum growths of all isolates were recorded in V-8 Juice Agar (V8JA) followed by Potato Dextrose Agar (PDA) while the minimum growth of pathogen was observed in Corn Meal Agar (CMA).

A simple method for conidial production and establishing latent infections of apples by Phlyctema vagabunda (syn: Neofabraea alba)

A method was developed to inoculate and establish infection of detached apple fruit with the bull’s eye rot pathogen, Phlyctema vagabunda (syn: Neofabraea alba), without wounding. Mycelial cultures of P. vagabunda did not produce conidia on commonly used potato dextrose agar, or several other tested media. Growth on corn meal agar resulted in the highest conidial yield, and maximum production was achieved after 5 days. These conidia were placed on water agar, and apple fruit were placed on these spores for at least 5 days for establishment of infections. Reliable infection of 66—100% of apples required 14 days of contact. The ability to rapidly produce copious quantities of conidia and inoculate without wounding facilitates a number of other postharvest control and epidemiology studies.

Chemosyndrome Variation in Mycobiont Culture and Thallus of Parmelina carporrhizans and Parmelina quercina

We cultured Parmelina carporrhizans and P. quercina in Corn Meal Agar and 0.2% glucose Malt Yeast Agar for 160 days. Chemosyndrome of natural thalli and mycobiont cultures were analyzed by HPLC. Lecanoric acid, atranorin, chloratranorin and ergosterol were detected in P. carporrhizans thalli, while lecanoric acid, chloratranorin and aliphates were found in P. quercina thalli. The secondary methabolites pattern between thalli and mycobiont culture was completely different in both species. Both species secreted the phenalenone myeloconone C in culture media and was also detected in P. quercina mycobiont aggregates. Interestingly, the phenolic compounds produced by the mycobiont culture of P. carporrhizans are related to those produced by natural thallus by the same biosynthetic pathway, while the chemosyndrome of P. quercina mycobiont implies switch of biosynthetic pathway from acetate-polymalonate pathway to shikimic acid pathway, with pulvinic acid as major compound of mycobiont culture. The role of Myelochonone C, confluentic acid and pulvinic acid produced by mycobiont culture is discussed as possible adaptive vantage in field as photoprotective agent or as byproduct result of stressing artificial culture conditions.

A simple method for conidial production and for inoculating apples with Neofabraea alba

Current methods for producing conidia of Neofabraea alba the fungal cause of Bulls eye rot of apple are laborious and timeconsuming A minimum of 6 weeks is required Mycelial cultures of N alba did not produce conidia on commonly used potato dextrose agar and therefore several other media were tested Growth on corn meal agar resulted in a high conidial yield (ca 106 conidia/ml) after 57 days growth Published research reports a method to inoculate apples with this pathogen without wounding but it requires specialised equipment A simple method that does not require specialised equipment was developed to inoculate apple fruit with the Bulls eye rot pathogen without wounding Conidia were placed on water agar and apple fruit were placed on these spores for at least 5 days for establishment of infections Reliable infection of 7080 of apples required a 14day wetness period after the fruit were placed on the conidial solution This woundfree N alba inoculation method provides the basis for further research to examine the effect of various treatments designed to reduce the impact of this pathogen in apple orchards

Culture and physiological variability in Rhizoctonia solani, responsible for foliar and lesions on aerial part of soybean

Foliar blight of soybean is one of the major fungal diseases. Rhizoctonia solani isolated from soybean growing in tarai regions of Uttarakhand. Six isolates of R. solani has been characterized on the basis of cultural and physiological nature such as colony diameter, growth, colour and sclerotia formation were recorded. Potato Dextrose Agar (PDA) was found best for growth and development. Two isolates (Lakhimpur and Pantnagar) covered the whole plates (90 mm) in 48 hrs. However, maximum number of sclerotia and weight was recorded on Czapek Dox agar medium. Overall radial growth supporting is recorded Corn Meal Agar Medium. Varied range of temperatures i.e. 10, 15, 25, 30, 35 and 400C was tested and found better growth of different isolates of R. solani at 10 - 400C, with an optimum growth temperature at 300C. Isolates were grown on five broth media (Asthana & Hawkers, Potato Dextrose Agar, Czapek’s Dox Agar, Corn Meal Agar and Richards Agar) for fresh, dry weight and oat meal broth culture filtrates of all isolates was used in phytotoxic effects. It recorded that maximum fresh and dry weight was observed on corn meal agar medium. The maximum reduction in radical and plumule length of germinating seeds were recorded in Haldichaur isolate.

Isolation spore production and Kochs postulates of Elsinoe pyri

Elsinoe leaf and fruit spot is a minor disease of apple and pear Very little is known of the biology and life cycle of the causal agent Elsinoe pyri The fungus was isolated from spots on apple fruit and grew very slowly on potato dextrose agar (PDA) The conditions needed for spore production were examined using different culturing media plating techniques and culture ages When small pieces of a 2 to 6weekold culture from PDA were subcultured onto corn meal agar for 2 days viable conidia were produced Conidial germination occurred between 10C and 26C with the highest germination percentage at 20C and 26C and greatest germination tube elongation at 20C At least 200 conidia per leaf were required to infect Royal Gala leaves Typical elsinoe spots were visible 6 weeks after inoculation Four months after inoculation conidia from the spots were reisolated onto PDA and grew into typical colonies of E pyri

Antifungal (Gaeumannomyces graminis var. tritici) activity of various glycosides of medicagenic acid

Different concentrations of medicagenic acid and five glycosides of this acid isolated from alfalfa (<i>Medicago sativa</i>) were added to agar medium (corn meal agar, CMA) inoculated with cultures of <i>Gaeumannomyces graminis</i> var. <i>tritici</i> (Ggt). After 7 days of incubation at 25^oC colony radius was measured and % of inhibition calculated in relation to the control medium (CMA enriched with the solvent of the tested compounds). Within the tested concentrations, only 3-O-<i>β</i> -D -glucopiranoside medicagenate (monoglucoside) significantly reduced the growth of Ggt on CMA medium. This compound at 0.05 mM concentration completely inhibited the development of the fungus and the effect was shown to be fungi-toxic.

Screening for Indian isolates of egg-parasitic fungi for use in biological control of fascioliasis and amphistomiasis in ruminant livestock

Wild isolates of the egg-parasitic fungiPaecilomyces lilacinusandVerticillium chlamydosporium, obtained from the organic environment of Durg, Chhattisgarh, India, were subjected to screening forin vitrogrowth using different media types, range of incubation temperature and pH, and their predatory activity to the eggs ofFasciola giganticaandGigantocotyle explanatum. Maximum growth ofP. lilacinuswas obtained in corn-meal agar compared to any other media types. The preferred medium for growth ofV. chlamydosporiumwas corn-meal agar, followed by potato-dextrose agar. After initial growth for 16 h of incubation, no growth was observed in water agar for both the fungi. Six different temperatures – 4°C, 10°C, 18°C, 26°C, 34°C and 40°C – were used to observe growth profiles of the fungi in corn-meal agar medium. While no and very little growth ofP. lilacinusandV. chlamydosporiumwas observed at 4°C and 10°C, respectively, growth profiles of both the fungi were optimal at 26–40°C. A range of pH (pH 4–8) supported growth of bothP. lilacinusandV. chlamydosporium. Full-grown plates of the fungi baited with viable eggs ofF. giganticaandG. explanatumrevealed thatV. chlamydosporiumwas more vigorous in its egg-parasitic ability compared toP. lilacinus. Distortion of the eggs started on day 2–3 of egg baiting in culture plates ofV. chlamydosporium, with complete distortion by day 7. On the contrary,P. lilacinusexhibited very limited egg-parasitic ability and some of the baited eggs even showed development of miracidia.