Abstract
In the phytopathogenic fungus Sporisorium scitamineum, sexual mating between two compatible haploid cells and the subsequent formation of dikaryotic hyphae is essential for infection. This process was shown to be commonly regulated by a mitogen-activated protein kinase (MAPK) and a cAMP/PKA signaling pathway in the corn smut fungus Ustilago maydis but remains largely unknown in S. scitamineum. In this study, we identified a conserved putative MAP kinase Kpp2 in S. scitamineum and named it as SsKpp2. The sskpp2Δ mutant displayed significant reduction in mating/filamentation, which could be partially restored by addition of cAMP or tryptophol, a quorum-sensing molecule identified in budding yeast. Transcriptional profiling showed that genes governing S. scitamineum mating or tryptophol biosynthesis were significantly differentially regulated in the sskpp2Δ mutant compared to the WT, under mating condition. Our results demonstrate that the MAP kinase SsKpp2 is required for S. scitamineum mating/filamentation likely through regulating the conserved pheromone signal transduction pathway and tryptophol production.
Highlights
The basidiomycetous fungus Sporisorium scitamineum causes sugarcane smut that leads to severe economic losses in the major sugarcane growing areas in China, India, and Brazil
The SsKPP2 open reading frame (ORF) was replaced by the recombinant hygromycin (HPT)-resistant selection marker, derived from two PCR amplified truncated but partially overlapped HPT fragment flanked by 5 - and 3 - untranslated region (UTR) of the SsKPP2 ORF (Supplementary Figure S1A)
Mitogen-activated protein kinase is protein kinase highly conserved in eukaryotic organisms as signal transducers (Kultz and Burg, 1998; Roman et al, 2007)
Summary
The basidiomycetous fungus Sporisorium scitamineum causes sugarcane smut that leads to severe economic losses in the major sugarcane growing areas in China, India, and Brazil. There are three distinct stages in the pathogenic life cycle of S. scitamineum, namely the haploid sporidium, the dikaryotic hyphae, and the diploid teliospore stages. The yeast-like and non-pathogenic sporidia are of two opposite mating types, MAT-1 (+) and MAT-2 (−). The compatible sporidia fuse to form dikaryotic hypha, which are capable of infecting the host plant. Diploid teliospores form in planta by nuclear fusion, and go through a round of meiosis to form four haploid sporidia again (Sundar et al, 2012). Sexual mating and the subsequent filamentous growth (filamentation) is a prerequisite for host cane infection. Our knowledge on molecular basis of S. scitamineum mating/filamentation is very limited
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
