Development of Cleaved Amplified Polymorphic Sequence Marker for Cap Color Identification in Pleurotus cornucopiae

Abstract

Cap color is one of the most crucial commercial traits for oyster mushrooms, and dark-colored varieties are highly favored by consumers, yet they are relatively scarce on the market. There is an urgent need for the selection and breeding of dark oyster mushrooms. Previous studies identified PcTYR, a key gene that controls the cap color of Pleurotus cornucopiae, and four SNPs were identified based on a genome-level sequence comparison of the black and white gene pools for extreme traits in the segregating populations. In this study, we verified whether these SNPs were color-specific sites via specific primer design, PCR amplification, and enzyme digestion of the entire isolated population strains and developed CAPS/dCAPS markers for the early visual identification of cap color to assist material screening in cap color breeding. One CAPS marker, TYR-CAPS-3-2, was developed for identifying the cap color of oyster mushrooms. After digestion with the restriction endonuclease Mse I, the marker generated polymorphic bands that accurately and visually distinguished dark-colored (non-white) and white strains from the cap color-segregating population. Consequently, the application of this marker during the early growth stage of oyster mushrooms can facilitate molecular-marker-assisted selection, expediting the breeding process for dark-colored varieties.