System‐wide characterization of bZIP transcription factor proteins involved in infection‐related morphogenesis of Magnaporthe oryzae

Abstract

The basic-leucine zipper (bZIP) domain-containing transcription factors (TFs) function as key regulators of cellular growth and differentiation in eukaryotic organisms including fungi. We have previously identified MoAp1 and MoAtf1 as bZIP TFs in Magnaporthe oryzae and demonstrated that they regulate the oxidative stress response and are critical in conidiogenesis and pathogenicity. Studies of bZIP proteins could provide a novel strategy for controlling rice blast, but a systematic examination of the bZIP proteins has not been carried out. Here, we identified 19 additional bZIP TFs and characterized their functions. We found that the majority of these TFs exhibit active functions, most notably, in conidiogenesis. We showed that MoHac1 regulates the endoplasmic reticulum (ER)-stress response through a conserved unfolded protein response (UPR) pathway, MoMetR controls amino acid metabolism to govern growth and differentiation, and MoBzip10 governs appressorium function and invasive hyphal growth. Moreover, MoBzip5 participates in appressorium formation through a pathway distinct from that MoBzip10, and MoMeaB appears to exert a regulatory role through nutrient uptake and nitrogen utilization. Collectively, our results provide insights into shared and specific functions associated with each of these TFs and link the regulatory roles to the fungal growth, conidiation, appressorium formation, host penetration, and pathogenicity.

MoPpe1 partners with MoSap1 to mediate TOR and cell wall integrity signalling in growth and pathogenicity of the rice blast fungus Magnaporthe oryzae

“…S3C and D). We further examined the expression of genes essential for conidiation and found that the expression of MoCOM1 , MoHOX2 , MoCOS1 and MoSTUA were all reduced in the Δ Moppe1 mutant when compared with the wild‐type strain (Kim et al ., ; Nishimura et al ., ; Zhou et al ., ; Yang et al ., ; Tang et al ., ) (Supporting Information Fig. S4).…”

The ArfGAP protein MoGlo3 regulates the development and pathogenicity of Magnaporthe oryzae

“…By using DTT as an ER stress inducer, we demonstrated that MoGlo3 has a role in the ER stress response. In addition, we showed that MoGlo3 has a role in the UPR pathway mediated by MoHac1 and MoMck1 (Tang et al ., ; Yin et al ., ). Since ER stress is hypothesized to occur during infection and invasive hyphae growth and that the fully functional UPR is required for penetration and invasive hyphae growth (Tang et al ., ), the perturbed UPR pathway under ER stress in the Δ Moglo3 mutant might foretell a defect in pathogenicity.…”

The thioredoxin MoTrx2 protein mediates reactive oxygen species (ROS) balance and controls pathogenicity as a target of the transcription factor MoAP1 in Magnaporthe oryzae

“…Plant pathogens have evolved various strategies to rapidly detoxify ROS through cellular enzymatic and non‐enzymatic mechanisms. Many of these rapid oxidative stress responses are also regulated through stress‐responsive transcription factors (Apel and Hirt, ; Guo et al ., ; Kim et al ., 2009; Liu et al ., ; Qi et al ., ; Tang et al ., ). We have shown previously that the transcription factor MoAP1 is a key factor in the regulation of gene expression involved in the detoxification of oxidative stress by regulating laccase and peroxidase activities (Guo et al ., ).…”