QTL mapping reveals mating type gene LeHD1 regulating mycelial growth in shiitake mushroom, Lentinula edodes

Abstract

Mycelial growth plays a vital role in substrate colonization, and understanding the genetic mechanisms of mycelial growth is of great significance for the fundamental and applied interest in mushrooms. The existence of conserved pleiotropic genes for mating type and mycelial growth in Agaricales is worthy to be penetratingly explored. Herein in Lentinula edodes, we refined an 1176 kb QTL-hotspot region regulating mycelial growth rate by quantitative trait loci (QTL) mapping. The mating gene LeHD1 encoding homeodomain type 1 transcription factor was found in this QTL-hotspot, and was prioritized as a candidate gene. We then cloned and characterized LeHD1 in L. edodes. The coding sequence of the LeHD1 is 2650 bp in length and encodes 808 amino acids. To further explore the function of LeHD1 in mycelial growth, vectors for LeHD1-overexpression (OE) and LeHD1-RNAi were constructed and transformed into shiitake strain WX1. Overexpression of LeHD1 increased mycelial growth rate by 8.6% to 18.5%. Contrary to this, interference of LeHD1 caused an 8.5% to 26.8% decrease in mycelial growth rate. Taken together, these results demonstrate that LeHD1 promotes mycelial growth in L. edodes. To our knowledge, LeHD1 was the first mating homeodomain gene identified to regulate mycelia growth in mushrooms providing additional insights into the association between mycelial growth and sexual recognition loci.