School of BioSciences, University of Melbourne, Parkville, Vic., 3052, Australia.
Department of Animal, Plant and Soil Science, La Trobe Institute for Agriculture & Food, La Trobe University, AgriBio Building, Bundoora, Vic., 3086, Australia.
New Phytol. 2022 Feb;233(4):1750-1767. doi: 10.1111/nph.17898. Epub 2022 Jan 4.
Secondary cell walls (SCWs) in stem xylem vessel and fibre cells enable plants to withstand the enormous compressive forces associated with upright growth. It remains unclear if xylem vessel and fibre cells can directly sense mechanical stimuli and modify their SCW during development. We provide evidence that Arabidopsis SCW-specific Fasciclin-Like Arabinogalactan-proteins 11 (FLA11) and 12 (FLA12) are possible cell surface sensors regulating SCW development in response to mechanical stimuli. Plants overexpressing FLA11 (OE-FLA11) showed earlier SCW development compared to the wild-type (WT) and altered SCW properties that phenocopy WT plants under compression stress. By contrast, OE-FLA12 stems showed higher cellulose content compared to WT plants, similar to plants experiencing tensile stress. fla11, OE-FLA11, fla12, and OE-FLA12 plants showed altered SCW responses to mechanical stress compared to the WT. Quantitative polymerase chain reaction (qPCR) and RNA-seq analysis revealed the up-regulation of genes and pathways involved in stress responses and SCW synthesis and regulation. Analysis of OE-FLA11 nst1 nst3 plants suggests that FLA11 regulation of SCWs is reliant on classical transcriptional networks. Our data support the involvement of FLA11 and FLA12 in SCW sensing complexes to fine-tune both the initiation of SCW development and the balance of lignin and cellulose synthesis/deposition in SCWs during development and in response to mechanical stimuli.
次生细胞壁（SCs）在木质部导管和纤维细胞中使植物能够承受与直立生长相关的巨大抗压能力。木质部导管和纤维细胞是否能够直接感知机械刺激并在发育过程中改变其 SCW 仍然不清楚。我们提供的证据表明，拟南芥 SCW 特异性 Fasciclin-Like Arabinogalactan-proteins 11（FLA11）和 12（FLA12）可能是细胞表面传感器，可响应机械刺激调节 SCW 发育。与野生型（WT）相比，过表达 FLA11（OE-FLA11）的植物表现出更早的 SCW 发育，并且改变了 SCW 特性，在压缩应激下表现出 WT 植物的表型。相比之下，OE-FLA12 茎比 WT 植物具有更高的纤维素含量，类似于经历拉伸应力的植物。与 WT 相比，fla11、OE-FLA11、fla12 和 OE-FLA12 植物对机械应激的 SCW 反应发生改变。定量聚合酶链反应（qPCR）和 RNA-seq 分析显示，参与应激反应和 SCW 合成和调节的基因和途径上调。对 OE-FLA11 nst1 nst3 植物的分析表明，FLA11 对 SCWs 的调节依赖于经典的转录网络。我们的数据支持 FLA11 和 FLA12 参与 SCW 感应复合物，以微调 SCW 发育的启动以及木质素和纤维素合成/沉积在发育过程中的平衡，并响应机械刺激。
