On The Cover The KARRIKIN INSENSITIVE2 (KAI2) protein of Arabidopsis thaliana is required for plant responses to karrikins, which are a group of small butenolide compounds derived from burnt plant material. Shown here is the crystal structure of KAI2, with the core domain in green, the cap domain in purple, and the evolutionarily conserved catalytic triad of serine, histidine and aspartic acid residues (yellow). Hydrophobic side chains lining the active site are also shown. In this issue, Waters et al. show that addition of the karrikin KAR2 (lower left) to wild type Arabidopsis seedlings triggers the degradation of KAI2 protein. However, mutating the catalytic serine to alanine renders the protein nonfunctional and insensitive to degradation, suggesting that receptor degradation follows interaction between the ligand and the catalytic triad of KAI2. Image by: Mark Waters.
新植物学家：华中农大揭示稻瘟病菌侵蚀水稻的分子机制
在真核生物中，N6-methyladenosine (m6A)是一种对mRNA的修饰，该修饰对于RNA的功能至关重要。本研究作者鉴定到了一个稻瘟病菌中与人类参与m6A修饰的METTL4基因的同源基因MTA1。该基因的突变体mta1对水稻的侵蚀能力显著下降，同时该突变体中的细胞自噬过程出现紊乱：
MeRIP-seq分析鉴定了mta1突变体中659 个覆盖 595 个mRNAs的hypomethylated m6A peaks ，其中114个 m6A peaks与mRNA丰度成负相关关系，其中包括多个ATGs的转录本。通过突变分析，作者证实了参与细胞自噬的关键基因ATG8的修饰位点对于该基因的mRNA的丰度至关重要。
—本研究揭示了m6A甲基化修饰在M. oryzae侵袭水稻过程中的作用。
Working model of the mechanism of MTA1 regulates autophagy in an m6A-dependent manner. In this model, MTA1 regulates the m6A modification of autophagy-related proteins (ATG) gene’s transcripts, which in turn mediates mRNA degradation, therefore, the mRNA level of the ATG genes can be well balanced by m6A methylation and de-methylation. This mRNA level balance will contribute to ATG protein balance, and in turn coordinate the autophagic process (autophagosome ratio), thereby controls balance of autophagy in appressorium, and facilitates appressorium maturation and host penetration. Solid black arrows indicate proved process, and dashed black arrow indicates a predicted process. Interrogation mark means there could be a regulator protein to regulate the predicted de-methylation process.
原文信息：MTA1-mediated RNA m6A modification regulates autophagy and is required for infection of the rice blast fungus
