A PAS-Containing Histidine Kinase is Required for Conidiation, Appressorium Formation, and Disease Development in the Rice Blast Fungus,Magnaporthe oryzae

Abstract

Rice blast disease, caused by the ascomycete fungus Magnaporthe oryzae, is one of the most important diseases in rice production. PAS (period circadian protein, aryl hydrocarbon receptor nuclear translocator protein, single-minded protein) domains are known to be involved in signal transduction pathways, but their functional roles have not been well studied in fungi. In this study, targeted gene deletion was carried out to investigate the functional roles of the PAS-containing gene MoPAS1 (MGG_02665) in M. oryzae. The deletion mutant DMopas1 exhibited easily wettable mycelia, reduced conidiation, and defects in appressorium formation and disease development compared to the wild type and complemented transformant. Exogenous cAMP restored appressorium formation in DMopas1, but the shape of the restored appressorium was irregular, indicating that MoPAS1 is involved in sensing the hydrophobic surface. To examine the expression and localization of MoPAS1 in M. oryzae during appressorium development and plant infection, we constructed a MoPAS1:GFP fusion construct. MoPAS1:GFP was observed in conidia and germ tubes at 0 and 2 h post-infection (hpi) on hydrophobic cover slips. By 8 hpi, most of the GFP signal was observed in the appressoria. During invasive growth in host cells, MoPAS1:GFP was found to be fully expressed in not only the appressoria but also invasive hyphae, suggesting that MoPAS may contribute to disease development in host cells. These results expand our knowledge of the roles of PAS-containing regulatory genes in the plant-pathogenic fungus M. oryzae.

Phase-specific transcriptional patterns of the oomycete pathogen Phytophthora sojae unravel genes essential for asexual development and pathogenic processes

“…Many fungi have hybrid HKs (HHKs), in which the HK and RR domains coexist in a single polypeptide. These HHKs regulate various processes, such as environmental perception, cell cycle control, and morphological change from nonpathogenic to pathogenic forms [ 26 , 27 , 42 ]. Interestingly, the histidine kinase in our study was also a hybrid HK, containing HK integrated with RR domains ( Fig 4A ).…”

“…Several studies have demonstrated the roles of histidine kinases in sensing environmental signals [24,25] and regulating sexual development and virulence [26,27]. The putative histidine kinase (Ps130388) indicated the importance of signal recognition and regulation in P. sojae during development.…”

Red light‐regulated interaction of Per‐Arnt‐Sim histidine kinases with partner histidine‐containing phosphotransfer proteins in Physcomitrium patens

“…This suggests diverse subcellular localization of PHK proteins among early‐diverging lineages of land plants. In contrast to plant HKs, most fungal HKs are supposed to be soluble and cytoplasmic proteins (Alvarez et al., 2016; Meena et al., 2010; Shin et al., 2019). Alvarez et al., (2016) discussed a possibility that fungal HKs migrate from the cytoplasm into the nucleus, where they could directly interact with regulator proteins, independent of MSP signaling.…”

The Devastating Rice Blast Airborne Pathogen Magnaporthe oryzae—A Review on Genes Studied with Mutant Analysis

“…Its deletion mutants exhibited an impaired melanin layer, decreased appressorium turgor pressure, and attenuated virulence [ 201 , 202 ]. The histidine kinase PAS1 (period circadian protein, aryl hydrocarbon receptor nuclear translocator protein, and single-minded protein) is also required for mycelia and conidial development, appressoria formation, and pathogenicity [ 203 ]. Several HIKs-encoding genes, HIK1 to HIK9 , have been identified, and their single-deletion mutants have been functionally characterized.…”