Table_7_A Calcineurin Regulator MoRCN1 Is Important for Asexual Development, Stress Response, and Plant Infection of Magnaporthe oryzae.XLSX

The calcium/calcineurin signaling pathway plays a key role in the development and virulence of plant pathogenic fungi, but the regulation of this signaling pathway is still not clear. In this study, we identified a calcineurin regulator MoRCN1 in the plant pathogenic fungus Magnaporthe oryzae and found it is important for virulence by regulating the calcineurin pathway. MoRCN1 deletion mutants were severely decreased in colony growth and conidia formation. More importantly, the deletion of MoRCN1 led to a significant reduction in virulence due to defects in appressorium formation and invasive growth. The ΔMorcn1 mutants were more sensitive to different stresses and induced host ROS accumulation, suggesting a role of MoRCN1 in stress adaptation. We found that MoRCN1 directly interacted with the calcineurin catalytic subunit MoCNA and affected its protein stability, which was therefore important for regulating the calcineurin pathway. Transcriptome analysis showed that MoRCN1 significantly activated 491 genes and suppressed 337 genes in response to calcium ion, partially overlapped with the MoCRZ1-bound genes. Gene Ontology and KEGG pathway analyses indicated that MoRCN1-regulated genes were enriched in stress adaptation, lipid metabolism, and secondary metabolite biosynthesis, reflecting a function of MoRCN1 in host cell adaptation. Altogether, these results suggest MoRCN1 functions as a regulator of the calcium/calcineurin signaling pathway for fungal development and infection of host cells.

钙/钙调神经磷酸酶信号通路（calcium/calcineurin signaling pathway）在植物病原真菌的发育与致病过程中发挥关键作用，但目前该信号通路的调控机制仍尚不明确。本研究在植物病原真菌稻瘟病菌（Magnaporthe oryzae）中鉴定得到钙调神经磷酸酶调控因子MoRCN1，且发现其通过调控钙/钙调神经磷酸酶信号通路对病菌致病力至关重要。MoRCN1基因敲除突变体的菌落生长与分生孢子形成能力均显著下降。更为关键的是，ΔMorcn1突变体因附着胞形成与侵入生长出现缺陷，导致致病力显著降低。ΔMorcn1突变体对多种胁迫更为敏感，且会诱导宿主活性氧（reactive oxygen species, ROS）积累，表明MoRCN1参与胁迫适应过程。研究发现MoRCN1可直接与钙调神经磷酸酶催化亚基MoCNA相互作用，并影响其蛋白稳定性，进而对钙/钙调神经磷酸酶信号通路的调控发挥重要作用。转录组（transcriptome）分析显示，在钙离子胁迫下，MoRCN1可显著激活491个基因、抑制337个基因，该调控谱与MoCRZ1的结合靶基因存在部分重叠。基因本体论（Gene Ontology）与KEGG通路（KEGG pathway）富集分析表明，MoRCN1调控的基因富集于胁迫适应、脂质代谢及次生代谢产物生物合成等通路，反映出MoRCN1在宿主细胞适应过程中的功能。综上，上述结果表明MoRCN1作为钙/钙调神经磷酸酶信号通路的调控因子，参与真菌发育与宿主细胞侵染过程。