State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, People's Republic of China.
PLoS Pathog. 2011 Dec;7(12):e1002385. doi: 10.1371/journal.ppat.1002385. Epub 2011 Dec 1.
The cyclic AMP-dependent protein kinase A signaling pathway plays a major role in regulating plant infection by the rice blast fungus Magnaporthe oryzae. Here, we report the identification of two novel genes, MoSOM1 and MoCDTF1, which were discovered in an insertional mutagenesis screen for non-pathogenic mutants of M. oryzae. MoSOM1 or MoCDTF1 are both necessary for development of spores and appressoria by M. oryzae and play roles in cell wall differentiation, regulating melanin pigmentation and cell surface hydrophobicity during spore formation. MoSom1 strongly interacts with MoStu1 (Mstu1), an APSES transcription factor protein, and with MoCdtf1, while also interacting more weakly with the catalytic subunit of protein kinase A (CpkA) in yeast two hybrid assays. Furthermore, the expression levels of MoSOM1 and MoCDTF1 were significantly reduced in both Δmac1 and ΔcpkA mutants, consistent with regulation by the cAMP/PKA signaling pathway. MoSom1-GFP and MoCdtf1-GFP fusion proteins localized to the nucleus of fungal cells. Site-directed mutagenesis confirmed that nuclear localization signal sequences in MoSom1 and MoCdtf1 are essential for their sub-cellular localization and biological functions. Transcriptional profiling revealed major changes in gene expression associated with loss of MoSOM1 during infection-related development. We conclude that MoSom1 and MoCdtf1 functions downstream of the cAMP/PKA signaling pathway and are novel transcriptional regulators associated with cellular differentiation during plant infection by the rice blast fungus.
环腺苷酸依赖的蛋白激酶 A 信号通路在调控稻瘟病菌（Magnaporthe oryzae）感染植物中起着重要作用。在此，我们报告了两个新基因 MoSOM1 和 MoCDTF1 的鉴定，它们是在稻瘟病菌非致病性突变体的插入诱变筛选中发现的。MoSOM1 或 MoCDTF1 对于稻瘟病菌孢子和附着胞的发育都是必需的，在孢子形成过程中，它们在细胞壁分化、黑色素沉着和细胞表面疏水性调节中发挥作用。MoSom1 与 APSES 转录因子蛋白 MoStu1（Mstu1）和 MoCdtf1 强烈相互作用，而在酵母双杂交试验中与蛋白激酶 A 的催化亚基（CpkA）的相互作用较弱。此外，在Δmac1 和 ΔcpkA 突变体中，MoSOM1 和 MoCDTF1 的表达水平都显著降低，这与 cAMP/PKA 信号通路的调节一致。MoSom1-GFP 和 MoCdtf1-GFP 融合蛋白定位于真菌细胞的细胞核中。定点突变证实，MoSom1 和 MoCdtf1 中的核定位信号序列对于它们的亚细胞定位和生物学功能是必需的。转录谱分析显示，与 MoSOM1 在感染相关发育过程中缺失相关的基因表达发生了重大变化。我们的结论是，MoSom1 和 MoCdtf1 作为细胞分化的新转录调节剂，在稻瘟病菌侵染植物过程中，其功能位于 cAMP/PKA 信号通路的下游。
