Identification of Degenerate Nuclei and Development of a SCAR Marker for Flammulina velutipes

Abstract

Flammulina velutipes is one of the major edible mushrooms in the world. Recently, abnormalities that have a negative impact on crop production have been reported in this mushroom. These symptoms include slow vegetative growth, a compact mycelial mat, and few or even no fruiting bodies. The morphologies and fruiting capabilities of monokaryons of wild-type and degenerate strains that arose through arthrospore formation were investigated through test crossing. Only one monokaryotic group of the degenerate strains and its hybrid strains showed abnormal phenotypes. Because the monokaryotic arthrospore has the same nucleus as the parent strain, these results indicated that only one aberrant nucleus of the two nuclei in the degenerate strain was responsible for the degeneracy. A sequence-characterized amplified region marker that is linked to the degenerate monokaryon was identified based on a polymorphic sequence that was generated using random primers. Comparative analyses revealed the presence of a degenerate-specific genomic region in a telomere, which arose via the transfer of a genomic fragment harboring a putative helicase gene. Our findings have narrowed down the potential molecular targets responsible for this phenotype for future studies and have provided a marker for the detection of degenerate strains.

Successive mycelial subculturing decreased lignocellulase activity and increased ROS accumulation in Volvariella volvacea

“…In the case of Yin et al (2017) , it was shown that strains began to degenerate at the third generation, with their fruiting bodies displaying incomplete growth on the fourth one. Finally Kim et al (2014) , reported slow vegetative growth, tight mycelial pads, and few or no fruiting bodies as some of the symptoms of degraded F. velutipes strains. In line with the above, and particularly the findings of ( Sun et al, 2017 ), this study showed that the density of aerial mycelia, along with their growth rate and biomass, gradually decreased as the degeneration level increased ( Figure 1 ).…”

Characteristics Analysis Reveals the Progress of Volvariella volvacea Mycelium Subculture Degeneration

“…They were not detected in the normal strains in fruiting-impaired degenerative isolates. Kim et al (2014) reported that the symptoms of degenerated F. velutipes strains include slow vegetative growth, a compact mycelial mat, and few, or even no, fruiting bodies. Yin et al (2017) artificially cultured the entomopathogenic mushroom Cordyceps militaris for six generations and observed changes during fruiting-body growth.…”

“…In this study, there was no significant difference in the mycelial biomass between M1 and M0 ( P > 0.05), but there were significant differences in the mycelial biomasses between M2–M6 and M0 ( P < 0.05) (Figure 2). Thus, the mycelial biomasses of degenerated strains decreased continuously as the subculturing continued, which might result in unsatisfying, and even a lack of, output from degenerated strains (Kim et al, 2014; Chen et al, 2017; Yin et al, 2017). Moreover, we discovered a similar trend between the mycelial growth rate and mycelial biomass as the subculturing continued.…”

“…However, the excessive subculturing of edible mushrooms may cause degeneration (Chen et al, 2017; Yin et al, 2017). Degenerated edible mushrooms are characterized by slim, fragile, and slow-growing mycelia (Magae et al, 2005; Kim et al, 2014).…”

Development of a Molecular Marker for Fruiting Body Pattern inAuricularia auricula-judae

“…Some recent studies have reported the use of SCAR markers for edible fungi. For example, they have been used in studies on the color of the fruiting bodies of Agaricus bisporus [ 12 ], Flammulina velutipes [ 13 ] and Hypsizygus marmoreus [ 14 ], the degeneration of Volvariella volvacea strains [ 15 ] and F. velutipes [ 16 ], mushroom disease in Auricularia polytricha [ 17 ], and the mating types of edible fungi [ 18 , 19 ]. These markers have also been used to screen for various traits during breeding.…”