Bast fibers and products derived from them are undergoing a resurgence in demand in the global market. However, fungal diseases have become an important factor limiting their yield and quality, causing devastating consequences for the production of bast fiber crops in many parts of the world. Thus, there is a high demand for effective control and prevention strategies against fungal pathogens. Having rapid, specific, sensitive, and cost-effective tests that can be used for early and accurate diagnosis of disease agents is an essential step of such strategies. The objective of this study was to review the current status of research on molecular diagnosis of fungal pathogens on bast fiber crops. Our search of PubMed identified nearly 20 genera of fungal pathogens on bast fiber crops, among which the five most common genera were Colletotrichum, Pythium, Verticillium, Fusarium, and Golovinomyces. The gene regions that have been used for molecular identifications of these fungi include internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), s-tubulin, calmodulin (CAL), histone subunit 3 (H3), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), etc. We summarize the molecular assays that have been used to identify these fungi and discuss potential areas of future development for fast, specific, and accurate diagnosis of fungal pathogens on bast fiber crops.

https://www.mdpi.com/2076-0817/9/3/223/pdf

Molecular Diagnostics and Pathogenesis of Fungal Pathogens on Bast Fiber Crops.

Although Botryosphaeria species are known to cause cankers and dieback in many different woody hosts,
their importance in grapevines has been largely ignored. Indeed, they are more often regarded as saprophytes or
weak pathogens. In the work presented here the species of Botryosphaeria associated with wood and trunk diseases
of grapevines in Portugal were determined. Three species, namely, B. obtusa, B. parva, and B. lutea, were regularly
associated with trunk dieback, wood necrosis, brown wood streaking, cane bleaching or incomplete grafts.
Botryosphaeria parva was the most common and widely distributed species. Botryosphaeria dothidea and B. stevensii
were less common; the former was found on bleached canes and on necrotic tissues at the graft union while the latter
was isolated from necrotic buds, and occasionally from brown streaks in the wood. These data indicate that B. parva
is associated with many of the symptoms normally linked with infection by other fungi in the grapevine decline
syndrome. To stimulate further research on this genus, descriptions of the species associated with grapevines and an
identification key are provided.

Botryosphaeria species associated with diseases of grapevines in Portugal [Vitis vinifera L.]

Production of Volatile Compounds by a Variety of Fungi in Artificially Inoculated and Naturally Infected Aquilaria malaccensis

Henuk JBD, Sinaga MS, Hidayat SH. 2017. Morphological and molecular identificationof fungal pathogens causing gummosis disease of Citrus spp. in Indonesia. Biodiversitas 18: 1100-1108. Gummosis is one of the most important diseases of citrus. The disease is caused by several species of Phytophthora, i.e. P. nicotianae, P. palmivora, P. citrophthora; as well as Lasiodiplodia theobromae (synonyms: Botryodiplodia theobromae and Diplodia natalensis; teleomorph Botryosphaeria rhodina). The objective of this study was to identify the isolates of fungal pathogens, i.e. Phytophthora spp. and B. theobromae and/or D. natalensis from several different areas of citrus central production in Indonesia based on their morphological and molecular characteristics. This study included two activities, i.e. (i) collection, isolation, and identification of pathogenic fungi from infected tissues, basal stem roots, and soil surface and rhizosphere; and (ii) extraction of genomic DNA and amplification of DNA fragments using PCR technique for molecular characterization. Results of morphological characterization and DNA sequence analysis revealed that gummosis was caused by Botryodiplodia theobromae Pat. (Teleomorph Botryosphaeria rhodina (Cooke) Arx.)), and P. citrophthora.

/pdf/morphological-and-molecular-identificationof-fungal-2b46r3nlsq.pdf

Morphological and molecular identificationof fungal pathogens causing gummosis disease of Citrus spp. in Indonesia

Symptoms of leaf blight, stem canker, and pod rot were observed on T. cacao during a series of samplings conducted in several states of Malaysia from September 2018 to March 2019. The identity of the pathogen that was responsible for the diseases was determined using morphological characteristics, DNA sequences, and phylogenetic analyses of multiple genes, namely, internal transcribed spacer (ITS), elongation translation factor 1-alpha (tef1-α), β-tubulin (tub2), and RNA polymerase subunit II (rpb2). A total of 57 isolates recovered from diseased leaves of T. cacao (13 isolates), stems (20 isolates), and pods (24 isolates) showed morphological features that resembled Lasiodiplodia sp. The identity of the isolates was further determined up to the species level by comparing DNA sequences and phylogenetic analyses of multiple genes. The phylogenetic analysis of the combined dataset of ITS, tef1-α, tub2, and rpb2 elucidated that all of the isolates obtained were Lasiodiplodia theobromae as supported by 97% bootstrap value. The results of pathogenicity tests revealed L. theobromae as the causal pathogen of leaf blight, stem canker, and pod rot of T. cacao. 

/pdf/lasiodiplodia-theobromae-as-a-causal-pathogen-of-leaf-blight-2mnhrr9f.pdf

Lasiodiplodia theobromae as a causal pathogen of leaf blight, stem canker, and pod rot of Theobroma cacao in Malaysia

Kenaf (Hibiscus cannabinus) is a fibre crop grown in Malaysia as a substitute crop for tobacco. Previous study have recorded that kenaf has been infected by various genera of seed-borne pathogen include Fusarium, Synnematium, Alternaria, Colletotrichum and Botrytis. Seed-borne disease affects and actively attacks seeds and may be harmful. Lasiodiplodia theobromae is a seed-borne fungal pathogen that infects a variety of crop seeds. Studies on the isolation of seed-borne fungi on kenaf seed have revealed that L. theobromae causes black rot disease on kenaf seeds. L. theobromae was successfully isolated from kenaf seeds on an agar plate and a blotter. L. theobromae was isolated frequently from infected seeds and identified based on its cultural and morphological characteristics. The fungus sequence was analysed using molecular technique (ITS-rDNA amplification). A pathogenicity test was used to confirm that L. theobromae caused blackening of the seeds and reduced the germination against a control treatment in potato Dextrose Agar (PDA) medium. To our knowledge, this study is the first to confirm that L. theobromae is the causal agent of black rot on kenaf seed in Malaysia.

/pdf/morphological-pathogenic-and-molecular-characterization-of-xp0tdoq3mi.pdf

Morphological, pathogenic and molecular characterization of Lasiodiplodia theobromae: a causal pathogen of black rot disease on kenaf seeds in Malaysia

M. Norhayati

Papers

Morphological, pathogenic and molecular characterization of Lasiodiplodia theobromae: a causal pathogen of black rot disease on kenaf seeds in Malaysia