# Genome-Wide Identification, Phylogeny and Expressional Profiles of Mitogen Activated Protein Kinase Gene Family in Blakeslea trispora

## TL;DR

This study identifies and analyzes MAPK cascade genes in Blakeslea trispora, revealing their roles in stress response, light signaling, and sexual interaction.

## Contribution

The study provides the first genome-wide analysis of MAPK cascade genes in Blakeslea trispora, revealing their phylogeny and expression profiles.

## Key findings

- Blakeslea trispora has 19 MAPK cascade genes, including 9 BtMAPKKKs, 4 BtMAPKKs, and 6 BtMAPKs.
- BtHog2 shows increased transcription under blue light, indicating a role in light signal transduction.
- BtMAPKKK9 and BtBck1 are strongly induced during sexual interaction, suggesting roles in trisporic acid response.

## Abstract

In eukaryotes, the mitogen-activated protein kinase (MAPK) cascade pathway is a highly conserved cell signaling mechanism that is essential for stress response, growth, and development. MAPK cascade genes have currently been identified and characterized in a wide range of fungi, although they have not been fully understood in early divergent fungal lineages like the Mucoromycota, which contains Mucoromycotina, Glomeromycotina, and Mortierellomycotina. In this study, a genome-wide investigation of Blakeslea trispora (Mucorales, Choanephoraceae) revealed a total of 19 MAPK cascade genes, including 9 BtMAPKKKs, 4 BtMAPKKs, and 6 BtMAPKs genes. Using phylogenetic analysis, it was found that the kinase domain sequences and motif composition of the three MAPK, MAPKK, and MAPKKK lineages are substantially conserved in fungi. Whole genome duplication analysis indicated that B. trispora has four and nine duplication pairs in the MAPK and MAPKKK genes, respectively, which are expanded by segmental replication events. BtHog2, the orthologous protein of Hog1, exhibits a substantial rise in transcription levels under blue light irradiation, indicating its function in light signal response and transduction. Several sets of interacting protein pairs were found using molecular docking analysis and yeast two-hybrid assay, providing a comprehensive MAPK cascade signaling network in B. trispore. Furthermore, MAPK cascade proteins show varying transcription levels in response to blue light and sex hormone stimulation, as well as variable treatment duration. BtMAPKKK9 and BtBck1 are strongly induced during sexual interaction, indicating their involvement in the response to trisporic acid and the subsequent alterations in hyphal cell wall structure. These findings shed light on the evolution of MAPK cascade genes and the functional mechanisms underlying MAPK cascade genes in response to light and sex hormone signaling pathways in B. trispore.