A chemical and synthetic biology approach to control plant membrane receptor kinase signaling

Plants have a large family of membrane receptor kinases (RKs) which sense extracellular signals to control plant growth, development, immunity, and stress response. The largest group of RKs contains an extracellular leucine-rich repeat (LRR) domain with over 200 members in Arabidopsis. However, the functional understanding of most of the LRR-RKs has been hampered by their genetic redundancy and the subtle phenotypes of RK overexpression. Here we show that the rapamycin-mediated heterodimerization of chimeric cytosolic kinase domains from receptor/co-receptor pairs in the plasma membrane can activate their downstream cellular signaling pathway, inducing the specific biological responses, including brassinosteroid, plant immunity, stomatal development, and lateral root development. This chemically controlled synthetic biology approach will be useful to investigate biological functions of LRR-RKs and their signaling pathways. Arabidopsis seedlings were grown on medium containing 2 μM PPZ with 100 nM brassinolide or 100 nM rapamycin in the dark for 5 days before harvesting for total RNA extraction.

植物拥有庞大的膜受体激酶（membrane receptor kinases, RKs）家族，这类激酶可感知胞外信号，进而调控植物的生长、发育、免疫与胁迫应答。其中最大的一类RKs含有胞外富亮氨酸重复（leucine-rich repeat, LRR）结构域，在拟南芥中该家族成员数量超过200个。然而，受遗传冗余性以及RK过表达所引发的细微表型所限，学界对多数LRR-RKs的功能认知仍存在不足。本研究表明，将受体/共受体对的嵌合胞质激酶结构域在质膜上进行雷帕霉素介导的异源二聚化，可激活其下游细胞信号通路，诱发包括油菜素内酯响应、植物免疫、气孔发育以及侧根发育在内的特异性生物学响应。这种化学可控的合成生物学方法，将有助于解析LRR-RKs及其信号通路的生物学功能。研究人员将拟南芥幼苗接种于含2 μM PPZ、100 nM 油菜素内酯或100 nM 雷帕霉素的培养基中，于黑暗环境下培养5天后收获样本，用于总RNA提取。