Fang Hong, Shen Shuangqian, Wang Dan, Zhang Fan, Zhang Chongyang, Wang Zixuan, Zhou Qianqian, Wang Ruyi, Tao Hui, He Feng, Yang Chenkun, Peng Meng, Jing Xinyu, Hao Zeyun, Liu Xionglun, Luo Jie, Wang Guo-Liang, Ning Yuese
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; College of Agronomy, Hunan Agricultural University, Changsha 410128, China.
National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
Sci Bull (Beijing). 2021 Dec 15;66(23):2381-2393. doi: 10.1016/j.scib.2021.06.014. Epub 2021 Jun 13.
Phenolamides (PAs), a diverse group of specialized metabolites, including hydroxycinnamoylputrescine (HP), hydroxycinnamoylagmatine, and hydroxycinnamoyltryptamine, are important in plant resistance to biotic stress. However, the genes involved in the biosynthesis and modulation of PAs have not been fully elucidated. This study identified an HP biosynthetic gene cluster in rice (Oryza sativa) comprising one gene (OsODC) encoding a decarboxylase and two tandem-duplicated genes (OsPHT3 and OsPHT4) encoding putrescine hydroxycinnamoyl acyltransferases coexpressed in different tissues. OsODC catalyzes the conversion of ornithine to putrescine, which is used in HP biosynthesis involving OsPHT3 and OsPHT4. OsPHT3 or OsPHT4 overexpression causes HP accumulation and cell death and putrescine hydroxycinnamoyl acyltransferases (PHT) activity-dependent resistance against the fungal pathogen Magnaporthe oryzae. OsODC overexpression plants also confer enhanced resistance to M. oryzae. Notably, the basic leucine zipper transcription factor APIP5, a negative regulator of cell death, directly binds to the OsPHT4 promoter, repressing its transcription. Moreover, APIP5 suppression induces OsPHT4 expression and HP accumulation. Comparative genomic analysis revealed that the HP biosynthetic gene cluster is conserved in monocots. These results characterized a previously unidentified monocot-specific gene cluster that is involved in HP biosynthesis and contributes to defense and cell death in rice.
酚酰胺（PAs）是一类多样的特殊代谢产物，包括羟基肉桂酰腐胺（HP）、羟基肉桂酰胍丁胺和羟基肉桂酰色胺，在植物对生物胁迫的抗性中起着重要作用。然而，参与PAs生物合成和调控的基因尚未完全阐明。本研究在水稻（Oryza sativa）中鉴定出一个HP生物合成基因簇，该基因簇包含一个编码脱羧酶的基因（OsODC）和两个串联重复的基因（OsPHT3和OsPHT4），它们编码在不同组织中共表达的腐胺羟基肉桂酰酰基转移酶。OsODC催化鸟氨酸转化为腐胺，腐胺用于涉及OsPHT3和OsPHT4的HP生物合成。OsPHT3或OsPHT4的过表达导致HP积累和细胞死亡以及对真菌病原体稻瘟病菌的腐胺羟基肉桂酰酰基转移酶（PHT）活性依赖性抗性。OsODC过表达植株也对稻瘟病菌具有增强的抗性。值得注意的是，碱性亮氨酸拉链转录因子APIP5是细胞死亡的负调控因子，它直接与OsPHT4启动子结合，抑制其转录。此外，APIP5的抑制诱导OsPHT4表达和HP积累。比较基因组分析表明，HP生物合成基因簇在单子叶植物中是保守的。这些结果鉴定了一个以前未鉴定的单子叶植物特异性基因簇，该基因簇参与HP生物合成并有助于水稻的防御和细胞死亡。
