Effects of β-1,6-Glucan Synthase Gene (FfGS6) Overexpression on Stress Response and Fruit Body Development in Flammulina filiformis

Abstract

β-1, 6-glucan synthase is a key enzyme of β-1, 6-glucan synthesis, which plays a vital role in the cell wall cross-linking of fungi. However, the role of the β-1, 6-glucan synthase gene in the development of the fruiting body and the stress response of macrofungi is largely unknown. In this study, four overexpression transformants of the β-1, 6-glucan synthase gene (FfGS6) were successfully obtained, and gene function was studied in Flammulina filiformis. The overexpression of FfGS6 can increase the width of mycelium cells and improve the tolerance ability under mechanical injury and oxidative stress. Moreover, FfGS6 gene expression fluctuated in up-regulation during the recovery process of mycelium injury but showed a negative correlation with H2O2 concentration. Fruiting body phenotype tests showed that mycelia’s recovery ability after scratching improved when the FfGS6 gene was overexpressed. However, primordia formation and the stipe elongation ability were significantly inhibited. Our findings indicate that FfGS6 is involved in regulating mycelial cell morphology, the mycelial stress response, and fruit body development in F. filiformis.

Spermidine Synthase and Saccharopine Reductase Have Co-Expression Patterns Both in Basidiomycetes with Fusion Form and Ascomycetes with Separate Form

“…Besides the light and temperature, many cultivation substrates often bring oxidative stress and mechanical damage often occurs. During the growth of F. filiformis , we adopted the exogenous addition of H 2 O 2 (5 mM and 10 mM, according to Liu et al [ 20 ]) and MeJA (0.01 mM and 0.02 mM, according to Ren et al [ 21 ]) as two cases of environmental stress to detect the response expression of FfSpdsSr . The RT-qPCR results showed that FfSpdsSr significantly up-regulated under 10 mM H 2 O 2 treatment ( Figure 4 E) or under 0.01-0.02 mM MeJA treatment ( Figure 4 F).…”

“…For the temperature treatment, four gradients—15 °C (cold stress), 20 °C (low-temperature stress), 25 °C (the optimum temperature, as control), and 30 °C (high-temperature stress)—were used to cultivate F. filiformis mycelia after inoculation on CYM plate, according to the study of Lv et al [ 19 ]. Because fungi are often subjected to oxidative stress from growing substrates and mechanical damage from the external environment, the exogenous H 2 O 2 (5 mM and 10 mM, according to Liu et al [ 20 ]) as the representative of oxidative stress and exogenous MeJA (0.01 mM and 0.02 mM, according to Ren et al [ 21 ]) as the representative of mechanical damage (due to the previous study that showed mechanical damage acts through JA signal [ 22 ]) were added into the CYM medium to cultivate F. filiformis mycelia. All samples were wrapped in foil, quick-frozen in liquid nitrogen, and stored in a −80 °C freezer for future use.…”