Wang Huijuan, Li Han, Li Chaochao, Liu Shenghao, Zhang Pengying
National Glycoengineering Research Center, School of Life Science, Shandong University, Qingdao, 266237, China.
Marine Ecology Research Center, First Institute of Oceanography, Natural Resources Ministry, Qingdao, 266061, China.
BMC Plant Biol. 2025 Apr 28;25(1):549. doi: 10.1186/s12870-025-06578-8.
Flavonoid biosynthesis pathway is generally thought unique to land plants and has assisted plants to adapt the terrestrial ecosystems. In this pathway, four 2-oxoglutarate/Fe(II)-dependent dioxygenases (2-ODDs), i.e., flavone synthase I (FNSI), flavanone-3-hydroxylase (F3H), flavonol synthase (FLS) and anthocyanin synthase/leucoanthocyanidin dioxygenase (ANS/LDOX), catalyze the hydroxylation and desaturation reactions. In bryophytes, the earliest land plant group, little is known about the biological functions of these enzymes.
Here, we cloned a Pn2-ODD2 gene of flavonoid biosynthesis pathway from Antarctic moss Pohlia nutans, which was induced by exogenous NaCl, PEG and abscisic acid (ABA) treatment. Overexpression of Pn2-ODD2 increased the drought resistance in Physcomitrium patens and Arabidopsis thaliana during gametophyte growth and seed germination, respectively. Overexpressed-Pn2-ODD2 Arabidopsis also exhibited the enhanced tolerance to oxidative stress, with the downregulation of ROS generation gene and increased the total flavonoid content. Also, overexpression of Pn2-ODD2 decreased the ABA sensitivity in transgenic P. patens and Arabidopsis. Meanwhile, overexpression of Pn2-ODD2 resulted in an increase in both anthocyanins and flavonols in Arabidopsis, which was correlated with the up-regulated anthocyanin biosynthesis gene.
Taken together, Pn2-ODD2 conferred the resistance to drought and oxidative stress by regulating antioxidant defense system in plants.
类黄酮生物合成途径通常被认为是陆地植物所特有的，并且帮助植物适应陆地生态系统。在该途径中，四种2-酮戊二酸/铁（II）依赖性双加氧酶（2-ODD），即黄酮合酶I（FNSI）、黄烷酮-3-羟化酶（F3H）、黄酮醇合酶（FLS）和花青素合酶/无色花青素双加氧酶（ANS/LDOX），催化羟基化和去饱和反应。在苔藓植物（最早的陆地植物类群）中，关于这些酶的生物学功能知之甚少。
在此，我们从南极苔藓垂枝真藓中克隆了类黄酮生物合成途径的一个Pn2-ODD2基因，该基因在外源NaCl、聚乙二醇（PEG）和脱落酸（ABA）处理下被诱导。Pn2-ODD2的过表达分别在配子体生长和种子萌发期间增强了小立碗藓和拟南芥的抗旱性。过表达Pn2-ODD2的拟南芥对氧化胁迫的耐受性也增强，活性氧生成基因下调，总类黄酮含量增加。此外，Pn2-ODD2的过表达降低了转基因小立碗藓和拟南芥对ABA的敏感性。同时，Pn2-ODD2的过表达导致拟南芥中花青素和黄酮醇均增加，这与花青素生物合成基因的上调相关。
综上所述，Pn2-ODD2通过调节植物中的抗氧化防御系统赋予抗旱性和氧化胁迫耐受性。
