Phenotypic and genetic analysis of Flammulina velutipes in the response of light 

Breeding research of winter mushroom(Flammulina velutipes) has focused on advancing productivity and quality of white cultivar. However, the genetic and morphological similarities among white resources have posed limitations in developing superior or distinct varieties through crossing between white strains. Therefore, it is crucial to utilize diverse wild-type brown resources with high polymorphism in breeding programs. Studies on the physiological and molecular aspects related to color of fruitbody in F. velutipes need to be preceded to enhance the utilization of brown strains. Particularly, the color fruiting body exhibits dramatic color changes in response to light, but the underlying mechanisms are still unknown. In this study, we investigated the phenotypic characteristics of fruiting bodies under different light conditions and analyzed expression levels of gene involved in color regulation in F. velutipes. The ‘Aram’ variety was used and the samples just before harvest were subjected to four different light conditions (no treatment, red, green, and blue light) for 24 and 48 hours. The results showed no color changes in the no treatment and red light groups, while the intensity of color increased in the green light and blue light groups. Particularly, the samples treated with the blue light exhibited the lowest L-value, indicating a darker color. To examine the relationship between gene expression and phenotypic differences, the expression levels of the previously discovered color-related gene PAL(Phenylalanine Ammonia-Lyase) in F. velutipes were analyzed. Interestingly, the samples treated with blue light showed an up-regulation of PAL expression by 8-10 times at 24 hours and 2.5-4 times at 48 hours. It suggests that the expression of color-related genes influences the color changes in fruitbody of F. velutipes. Transcriptome analysis will be conducted to elucidate the biological mechanisms of mushroom color changes in response to light stress

This work was carried out with the support of “Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ01419602)” Rural Development Administration, Republic of Korea.