Volume 7 - 2024 - issue 2

1. Unravelling the Diversity, Root Colonization, and Morphological Features of Arbuscular Mycorrhizal Fungi Associated with Invasive Plant Species of Sirmaur, Himachal Pradesh, India

Authors: Kaur M, Singh PK

Recieved: 11 April 2024, Accepted: 26 June 2024, Published: 06 September 2024

This study assessed the diversity and colonization patterns of arbuscular mycorrhizal fungi (AMF) associated with selected invasive plant species, i.e., Parthenium, Cannabis, Mimosa, Lantana, and Asclepias spp. Soil samples were collected from the rhizosphere of five invasive plants in the Baru Sahib area, Sirmaur, Himachal Pradesh, India. The samples were analyzed using various methods, including wet-sieving, decanting, and microscopy. Fifty-six morphologically distinct AMF species belonging to 15 genera were identified. Glomus species were the most abundant, followed by Acaulospora and Rhizophagus. Parthenium hysterophorus exhibited the highest root colonization percentage (94.8%), while Asclepias curassavica had the lowest (61.6%). Lantana camara had the highest number of AMF spores in the soil samples, while Cannabis sativa had the lowest spore number. These findings provide valuable insights into the diversity and colonization patterns of AMF associated with invasive plant species, which can contribute to our understanding of the ecological interactions between invasive plants and soil microbial communities.

Keywords: Ecological impacts – Mycorrhization – Root Colonization – Symbiotic associations

2. Diversity and seasonal variations of endophytic fungi associated with Terminalia chebula Retz. (Combretaceae) of Tripura, India

Authors: Tripura S, Debbarma P, Paul S, Saha R, Datta BK, Saha AK.

Recieved: 04 May 2024, Accepted: 21 August 2024, Published: 23 September 2024

Endophytic fungi are microbes living within the interior organs of plants without showing any symptoms of the diseases. These fungi are recognized for their bioactivities, including antimicrobial, anticancer, antifungal, and antioxidant properties, etc. Despite having such importance, less research has been conducted to uncover the fungal endophytes colonizing different tissues of many important medicinal plants. Thus, the current study was undertaken to isolate and determine the diversity of culturable endophytic fungi associated with the medicinal plant Terminalia chebula Retz., collected from five different sites representing three different seasons (summer, monsoon and winter) in Tripura, Northeast, India. A total of 697 culturable endophytic fungal isolates were represented by sixteen genera, and a few sterile forms were recorded from 1,125 tissue segments of Terminalia chebula. The phylum Ascomycota dominated the endophytic fungal composition. The fungal endophytes like Diaporthe sp., Penicillium exsudans, Colletotrichum sp., and Corynespora torulosa were predominantly isolated from the host plant. The colonization and relative frequency of endophytic fungi were maximum in the leaf tissues, followed by barks and roots. The monsoon season harbored the maximum number of fungal isolates (285) compared to the summer (234) and winter (178) seasons. Significant differences were noted in the diversity of endophytic colonization among different study sites and various plant organs in different seasons. The diversity indices revealed maximum fungal diversity in the bark tissues compared to leaf and root tissues. The highest species richness was at the Jalaya site in comparison to the other sites while species diversity of fungal endophytes was highest during the summer season and lowest in winter. The results indicated that the study site, type of tissues and season influenced the endophytic fungal communities of the host plant, Terminalia chebula. These diverse endophytic fungi probably possess the ability to secrete bioactive compounds for curing several diseases, bioinoculants for plant protection, drug discovery in pharmaceutical sectors and biofertilizers in agricultural fields.

Keywords: Ascomycota – Chebulic myrobalan plant – Fungal diversity – Seasons

3. Fusarium oxysporum f. sp. lycopersici, the causal agent of vascular wilt disease of tomatoes: From its taxonomy to disease management

Authors: Rhouma A, Hajji-Hedfi L, Atallaoui K, Kouadri AM, Khrieba MI 2024

Recieved: 12 December 2023, Accepted: 26 August 2024, Published: 26 September 2024

Tomato (Solanum lycopersicum) is one of the world's most vital vegetable crops, holding immense agricultural, nutritional, and research significance. However, the Fusarium wilt disease, caused by Fusarium oxysporum f. sp. lycopersici, poses a severe threat to its global cultivation. This review paper focuses on the comprehensive management of Fusarium wilt disease and the associated taxonomic framework. It highlights the global significance of tomatoes, emphasizing their importance around the world. The review covers various aspects, including taxonomy and genetic variation of the pathogen, host range, disease symptoms, economic implications, factors affecting epidemiology, geographical distribution, disease cycle, and various management strategies. Moreover, it explores different management approaches, including chemical control, biological control, cultural practices, resistance breeding, soil solarization, and grafting. This comprehensive review underscores the strategies needed to protect tomato crops, ensuring food security on a global scale despite the challenges posed by Fusarium wilt.

Keywords: Fusarium wilt – management practice – Solanum lycopersicum – sustainable

4. Biology, diversity, detection and management of Plasmopara viticola causing downy mildew of grapevine (Vitis spp.)

Authors: Rhouma A, Hajji-Hedfi L, Atallaoui K, Chihani-Hammas N, Godwin Okon O.

Recieved: 15 February 2024, Accepted: 12 September 2024, Published: 11 October 2024

Grapevine downy mildew is a devastating disease that wreaks havoc on grapevines (Vitis vinifera L.) worldwide. The causal organism of this disease is Plasmopara viticola, a diploid obligate biotrophic oomycete native to North America. This pathogen has swiftly spread to grape-growing regions across the globe, particularly those blessed with warm, humid climates. Plasmopara viticola possesses a flexible mating system, employing both sexual and asexual means to propagate its lineage. Plasmopara viticola life cycle involves the production and dispersal of zoospores for grapevine infection. Zoospores produced within sporangia are released by rain or wind and swim in free water on the grapevine surface. They are attracted to stomata, where they encyst, germinate, and penetrate the host tissue. A substomatal vesicle develops, giving rise to intercellular mycelium. Under favorable conditions (warm, humid nights), sporulation occurs. Sporangiophores emerge through stomata, bearing sporangia that produce new zoospores. These zoospores are then dispersed by wind and rain to initiate new infection cycles on grapevine tissues. Meanwhile, P. viticola's resilience is further enhanced by its ability to produce thick-walled oospores, which can overwinter in infected leaf debris, ready to unleash a fresh wave of destruction in the following spring. Downy mildew's destructive reach extends to all green tissues of grapevines, leaving a trail of devastation in its wake. Infection of leaves cripples photosynthetic efficiency, leading to a decline in grape quality. The infection of inflorescences and berries directly translates into yield losses. The current mainstay of downy mildew control is a heavy reliance on fungicide treatments. However, this approach is riddled with drawbacks, including exorbitant expenses, potential threats to human health, environmental contamination, and the inevitable emergence of fungicide resistance. In light of these shortcomings, researchers are actively exploring alternative, ecologically sound strategies to curb downy mildew's rampage, aiming to strike an integrated disease management balance between effective disease control and environmental stewardship. This comprehensive review provides in-depth insights into P. viticola, encompassing its taxonomy, host-pathogen interactions, symptoms, economic impact, epidemiology, distribution, infection mechanisms, and control strategies, with a strong focus on sustainable methods.

Keywords: downy mildew – grapevine – management practice – Plasmopara viticola – sustainability

5. Spatial analysis vis a vis local perception of anthropogenic pressures on natural habitats of ectomycorrhizal fungi in Wari–Maro Forest Reserve in Benin

Authors: Teteli SC, Badou AS, Dramani R, De Kesel A, Sambieni KR, Diansambu MI, Kouton BN, Yorou SN.

Recieved: 28 March 2024, Accepted: 30 October 2024, Published: 22 November 2024

Forest ecosystems undergo profound changes due to the combined effects of human activities on carbon footprints and climate change. Although we have evidence of such disturbances, the direct impact on the availability of food resources for local populations is still poorly understood. The present study aims to assess the different changes induced by humans in the natural habitats of ectomycorrhizal fungi (ECM) over time. Two complementary approaches were used: spatial analysis by remote sensing and a survey approach to local perception. In the latter, Landsat satellite images from 2000, 2010, and 2020 were used to assess the spatio-temporal dynamics of land use over the past 20 years and to project changes for 2040. Land use of natural habitats of EcM over the past two decades was mapped using supervised classification to determine the changes. During the field survey, 238 individuals from eight villages surrounding the Forest Reserve of Wari–Maro (FR–WM) were interviewed. The spatial analysis results showed a 49.05% decline in the natural habitats of ectomycorrhizal fungi, from 72.39 % in 2000 to 23.34% in 2020, with a projected decline to 12.8 % by 2040. In contrast, anthropogenic land uses such as tree savannah, shrub savannah, cropland–fallow, and bare soil-housing have increased. Additionally, 87% of interviewed respondents confirmed that they have reduced their visits to the natural habitats of fungi in the FR–WM. The threats to fungal habitats, in increasing order, are agricultural expansion (13.87 %), logging (24.37 %), and grazing, especially overgrazing (43.7 %). Increasing demographics (35,29 %), land scarcity (23.05 %), and poverty (21 %) are considered the main drivers, leading to the above threats. These anthropogenic pressures have led to a significant loss of natural ECM habitats, resulting in a decrease in the natural production of edible fungi from 16,999.92 tons of fresh biomass in 2000 to 5,481.05 tons in 2020, a 58% reduction over 20 years. If this trend continues without intervention, this production is projected to decrease to 3,006.82 tons of fresh biomass by 2040. To mitigate these threats and establish sustainable conservation of these EcM natural habitats, appropriate measures must be applied and monitored by all stakeholders involved in the sustainable management of the Wari-Maro Forest reserve.

Keywords: Human disturbance – Benin – Dynamic – Ectomycorrhizal fungi – Natural habitat – Natural production

6. Fungal endophytes associated with actinorhizal plant species, Elaeagnus latifolia (Elaeagnaceae) and evaluating their antagonistic potential against grey blight disease in tea [causal agent: Pestalotiopsis theae] in North-East India

Authors: Handique L, Parkash V, Bhattacharyya PN, Sarma B.

Recieved: 02 March 2024, Accepted: 28 October 2024, Published: 07 December 2024

The current investigation explores the antagonistic potential of endophytic fungal diversity associated with Elaeagnus latifolia L., an actinorhizal plant species of North-east India against Pestalotiopsis theae, the causal agent of grey blight disease in tea. A total of 17 endophytic fungal isolates belonging to 14 different families and three phyla were isolated from various parts of the target plant species. The fungal isolates were characterized using a culture-based approach and microscopic tools and techniques, with particular emphasis on colony shape, size, spore formation characteristics, and fruiting body features. Nigrospora sp. showed the highest species density (0.5) amongst all of the fungal isolates. The highest isolation frequency (67%) was observed for Fusarium sp., Nigrospora sp., Penicillium chrysogenum and Rhizopus sp. A higher percentage of fungal isolates were obtained from the roots and stems (47% each) compared to leaves (29%). The maximum species richness and diversity indices were observed in stems (15.0), while the minimum values were found in leaves (9.0). The stem had the highest Shannon and Simpson diversity indices (2.02 and 0.860, respectively), followed by the root (1.979 and 0.847, respectively) and the leaves with the lowest values being 1.494 and 0.75, respectively. Among the fungal isolates tested for plant growth-promoting traits, such as phosphate solubilization, starch hydrolysis and efficiency in zinc solubilization, the isolate EF09 showed positive responses for all the tested parameters. The isolate EF09 showed maximum antifungal potential (up to 87.1%) against the significant tea pathogen, P. theae, in poisoned food technique in vitro. As there exists limited research related to hitherto-unexplored fungal endophytes associated with endemic plant species like E. latifolia, the current investigation holds sufficient promises in the isolation of novel bioactive molecules from these microbial isolates that might be useful in agriculture to develop sustainable strategies in plant protection in tea.

Keywords: Bioactive molecules – Culture-based approach – Endophytic fungal diversity – Plant growth-promoting traits – Plant protection – Species richness and diversity indices.

7. The genera Micarea and Brianaria in the Magadan Region (Far East of Russia)

Authors: Konoreva LA, Chesnokov SV, Zheludeva EV.

Recieved: 27 May 2024, Accepted: 05 November 2024, Published: 08 December 2024

The purpose of our study is to investigate the genera Micarea and Brianaria in the Magadan Region of the northern Russian Far East. The specimens stored in the herbaria of MAG and LE, along with collections from various districts of the Magadan Region collected between 2013 and 2021, were used as material for this paper. As a result of the research, sixteen species from the genera Brianaria and Micarea were identified. Among them, Brianaria bauschiana and Micarea rhabdogena are new to Asia; Micarea byssacea, M. pusilla and M. soralifera are reported for the first time in the Russian Far East, and nine species are new for the Magadan Region. Differences from related species and their distribution throughout Russia and nearby regions are discussed.

Keywords: Asia – biodiversity – Brianaria bauschiana – crustose lichens – distribution – Micarea rhabdogena

8. Optimization of Culture Conditions and Forced Wood Decay Assessment of Wood-rotting Mushrooms of Central Luzon, Philippines

Authors: Advincula EGC, Dulay RMR, Kalaw SP, Kimura K, Takenaka K, Reyes RG

Recieved: 14 May 2024, Accepted: 26 August 2024, Published: 11 December 2024

This paper reports the optimal conditions of six wood-rotting mushrooms of Central Luzon, Philippines. The wood degradation of the six mushrooms on selected tropical trees was also investigated. Coconut water agar was the most suitable culture medium for efficient mycelial growth. The optimal initial pH of coconut water agar for the six species was found to be 6 to 7. Four species preferred sealed conditions while the other two species showed comparable yields in both conditions. Light conditions were found to be more favorable than dark conditions for all species, except for Trametes cubensis, which preferred dark conditions. All macrofungal species prefer 30°C as the optimum temperature. In the forced wood decay assay, the highest weight loss was found in mango and gmelina wood blocks. Among the fungal species, Physisporinus lineatus showed the highest average percentage of weight loss.

Keywords: White Rot – Brown Rot – Polypores – Hymenochaetales – Culture Media

9. Plant growth-promoting and protective potential of root fungal endophytes associated with a pioneer grass, Saccharum spontaneum L., from a lahar-affected area

Authors: Cruz EM, dela Cruz TEE

Recieved: 29 April 2024, Accepted: 04 December 2024, Published: 17 December 2024

Root-associated mycobiota can improve nutrient assimilation and induce resistance in their host plants. In this study, we isolated root fungal endophytes (RFE) from Saccharum spontaneum, a pioneer grass thriving in a lahar-strewn environment. Seventeen root fungal endophytes identified as belonging to the genera Talaromyces, Penicillium, Fusarium, Trichoderma, Cladosporium, Epicoccum, Purpureocillium, and Rhizoctonia were screened for plant growth-promoting and protective properties. The colorimetric assay revealed significantly high levels of the phytohormone indole-3-acetic acid (20.13–159.89 µg/ml), which was produced by eight notable RFE isolates. Seven of the root fungal endophytes displayed phosphate solubilizing activities with a solubilization index (SI) ranging from 1.04–1.22 on Pikovskaya’s agar. Nine RFE isolates significantly suppressed the growth of the phytopathogen, Fusarium oxysporum, exhibiting > 50% inhibition rates in a dual culture experiment. Our study highlighted the beneficial traits of root fungal endophytes, which might be responsible for the successful colonization of lahar areas by the pioneer grass S. spontaneum.

Keywords: antagonism – beneficial fungi – IAA production – lahar – phosphate solubilization –plant hormones – tropical fungi

10. New species and new records of plant pathogenic fungi from northern Thailand

Authors: Armand A, Absalan S, Khongphinitbunjong K, Maharachchikumbura S, Hyde KD, Jayawardena RS

Recieved: 11 September 2024, Accepted: 06 December 2024, Published: 18 December 2024

Plant pathogenic fungi are significant in agricultural ecosystems, causing substantial economic losses worldwide. Understanding their diversity and distribution by exploring the poorly studied niches is essential for agricultural and horticultural production and effective disease management strategies. In this study, we conducted a comprehensive survey of plant pathogenic fungi on the Mae Fah Luang University premises, Thailand. Through morphological and multi-gene phylogenetic analyses, eight new fungus-host and five new geographical records are reported. Additionally, a new species, Neopestalotiopsis iridis, is illustrated and described. The survey revealed a diverse assemblage of fungal pathogens infecting various plant hosts, including economically important crops and ornamental plants. Our findings contribute to the knowledge of fungal biodiversity in northern Thailand and provide valuable insights into new niches of the species. This study underscores the importance of continued research efforts to monitor plant pathogenic fungi in different niches to increase our understanding of species diversity, distributions and evolutionary relationships.

Keywords: Bauhinia sp. – Iris pseudacorus – Jack fruit – Morinda citrifolia – Niches – Phytopathogens

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