Molecular Diagnostics and Pathogenesis of Fungal Pathogens on Bast Fiber Crops

Abstract

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), ß-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.Pathogens 2020, 9, 223 2 of 19 and control. However, conventional protocols based on morphological and physiological methods are time-consuming, require significant experience, and may not be sensitive and specific for individual pathogens [3]. Moreover, many fungal pathogens can remain latent in "sub-infection" stages with no obvious symptoms and/or in low numbers, making them difficult to detect, and causing confusion with their roles in diseases. These issues can contribute to delayed or wrong control measures.During the last three decades, to overcome these problems and minimize crop losses caused by fungal diseases, a diversity of DNA molecule-based tools has been developed for the detection and identification of fungal pathogens. These techniques include conventional polymerase chain reaction (PCR) [4], quantitative PCR (qPCR) [5,6], immunocapture-PCR (IC-PCR) [7,8], droplet digital PCR (dd-PCR) [9], loop-mediated isothermal amplification (LAMP) [10], multiplex tandem PCR [11], fluorescence in situ hybridization (FISH) [12], and DNA microarrays [3]. These methods are typically faster and more accurate than those based on colony morphology, microscopic features, and/or physiological/biochemical characters of pure fungal cultures. Indeed, methods targeting DNA sequences have been applied to detect pathogens during crops' growth, harvest and postharvest processing stages [13]. Moreover, they have also enabled a deeper understanding of microbial populations and communities associated with crops, especially the microorganisms that are difficult or impossible to cultivate in the lab. Together, technological advances and developments in DNA molecu...

Emerging diseases of Cannabis sativa and sustainable management

“…Methods for testing of plants to ensure they and the planting materials are free from pathogens are widely available and several commercial laboratories can provide detection services. PCR methods for detection of many species reported to infect cannabis and hemp, including Fusarium and Pythium , 21,69,70 as well as Golovinomyces species, 41,71 have been described. Hop latent viroid can be detected using molecular techniques 22,23,72 .…”

Nettle, a Long-Known Fiber Plant with New Perspectives

“…Bast fiber is one type of natural plant fiber coming from the sclerenchyma and associated with the phloem, as detailed in Section 3.2. This type of fiber is of interest because they represent a renewable source that can be used for composite materials for the textile, construction, or automobile industries [210]. Their natural abundance, biodegradability, and strength properties made them attractive as reinforcing agents in polymer composite industries [211].…”

Molecular Diagnostics and Detection of Oomycetes on Fiber Crops

“…The commonly used ones such as ITS, LSU rRNA, SSU rRNA, and EF-1α, are similar to those used for detecting fungal pathogens (Table 2, ref. [9]). These markers were often chosen mainly because sequence variations in these DNA fragments were effective for distinguishing closely related species.…”

“…Consequently, oomycete and fungal plant pathogens often appear together in the same papers in broad surveys of plant diseases. For example, Cheng et al [9] recently reviewed the current status of research on molecular diagnosis of fungal pathogens on bast fiber crops and included a few examples of oomycete pathogens in these crops. Indeed, there have been few systematic reviews on oomycete plant pathogens and no review on molecular detection of oomycete pathogens on fiber crops.…”