Abstract：
Initiation of plant vascular tissue is regulated by transcriptional networks during development and in response to environmental stimuli. The WALL-ASSOCIATED KINASES (WAKs) and WAK-likes (WAKLs) are cell surface receptors involved in cell expansion and defence in cells with primary walls, yet their roles in regulation of vascular tissue development that contain secondary walls remains unclear. In this study, we showed tomato (Solanum lycopersicum) SlWAKL2 and the orthologous gene in Arabidopsis thaliana, AtWAKL14, were specifically expressed in vascular tissues. SlWAKL2-RNAi tomato plants displayed smaller fruit size with fewer seeds and vascular bundles compared to wild-type (WT) and over-expression (OE) lines. RNA-seq data showed that SlWAKL2-RNAi fruits down-regulated transcript levels of genes related to vascular tissue development compared to WT. Histological analysis showed T-DNA insertion mutant wakl14-1 had reduced plant stem length with fewer number of xylem vessels and interfascicular fibres compared to WT, with no significant differences in cellulose and lignin content. Mutant wakl14-1 also showed reduced number of vascular bundles in fruit. A proWAKL14::mCherry-WAKL14 fusion protein was able to complement wakl14-1 phenotypes and showed mCherry-WAKL14 associated with the plasma membrane. In vitro binding assays showed both SlWAKL2 and AtWAKL14 can interact with pectin and oligogalacturonides. Our results reveal novel roles of WAKLs in regulating vascular tissue development.
摘要：
植物维管组织的起始在发育过程中和对环境刺激的响应中受到转录网络的调节。与壁相关的激酶（WAKs）和类WAK（WAKLs）是细胞表面受体，参与具有原代壁的细胞的细胞扩增和防御，然而，它们在调节含有次生壁的血管组织发育中的作用仍不清楚。在这项研究中,我们在拟南芥中显示了番茄（Solanumlycopersicum）SlWAKL2和直系同源基因，AtWAKL14在血管组织中特异性表达。与野生型（WT）和过表达（OE）品系相比，SlWAKL2-RNAi番茄植物显示出较小的果实大小，种子和维管束较少。RNA-seq数据显示,与WT相比,SlWAKL2-RNAi果实下调与血管组织发育相关的基因的转录水平。组织学分析显示，与WT相比，T-DNA插入突变体wakl14-1的植物茎长度减少，木质部血管和束间纤维数量减少，纤维素和木质素含量无显著差异。突变体wakl14-1还显示果实中维管束数量减少。proWAKL14::mCherry-WAKL14融合蛋白能够补充wakl14-1表型，并显示mCherry-WAKL14与质膜相关。体外结合测定显示SlWAKL2和AtWAKL14均可与果胶和低聚半乳糖醛酸相互作用。我们的结果揭示了WAKLs在调节血管组织发育中的新作用。
