Protein Trafficking During Fruiting Body Morphogenesis in Agaricus bisporus

摘要

Agaricus bisporus is commercially cultivated using a bi-layered substrate consisting of a lower-compost layer and upper-peat layer. To promote the rapid and uniform development of fruiting bodies, a standard practice in the North American mushroom industry is to seed each layer with an A. bisporus mycelial inoculant. Using a fl-glucuronidase (GUS) reporter system, we have previously shown that the genotype of the inoculant used in the upper layer was the dominant determinant of fruiting body genotype. Herein, we report that the upper-layer inoculant largely controlled fruiting body genotype even at a seeding rate that was 35% lower than the commercial standard. Moreover, results of our earlier studies using a GUS reporter revealed for the first time the long-distance trafficking of protein from transgenic mycelium colonizing the lower layer into a fruiting body developing from wild-type mycelium colonizing the upper layer. In the present study, we further demonstrate effective trafficking of GUS protein using a transgenic line (GGS) in which the native glyceraldehyde-3-phosphate dehydrogenase promoter controlled the gus gene. Colonizing the lower-compost layer with line GGS and upper-peat layer with a WT line produced a fruiting body with high GUS activity while lacking the gus gene. Throughout the cropping cycle, GUS enzyme activity in the mycelium increased during colonization of the compost and peat substrates and decreased during fruiting body development. GUS activity in the fruiting body was highest at the first-break harvest and decreased in synchrony with the characteristic decline in fruiting body productivity with time. Based on these data, we hypothesize that the mycelial network in the compost functions as a storage organ for mature proteins that are trafficked en masse in support of fruiting body development.