National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, 200444, China.
Sci Rep. 2017 Jul 21;7(1):6182. doi: 10.1038/s41598-017-06473-9.
In Populus, the transcripts of fasciclin-like arabinogalactan proteins (FLAs) are accumulated in tension wood (TW) xylem, however their biological functions in TW formation are largely unknown. In this work, we demonstrated that PtFLA6, one of poplar TW-associated PtFLAs, was abundantly expressed in TW, and mainly localized in differentiating G-fibers. The bended stems of PtFLA6 antisense transgenic poplar showed decreased transcripts of PtFLAs, including PtFLA6, and reduced PtFLA6 like proteins, leading to inhibited TW differentiation and formation. We also showed that gibberellin A3 (GA) was enriched in the xylem of TW side, accompanied with a lowered level of PtRGA1, a poplar DELLA protein. When GA biosynthesis was restrained in the bended poplar stems by a GA biosynthesis inhibitor (daminozide), TW formation was obviously repressed, as a result of restricted PtRGA1 degradation, and reduced PtFLA6 like proteins and PtFLA expression. Further studies indicated that PtFLAs were negatively regulated by PtRGA1. This study suggests that PtFLAs play important roles in the poplar TW formation, possibly regulated by GA signaling.
在杨属植物中，纤维连接蛋白样阿拉伯半乳聚糖蛋白（FLAs）的转录本在紧张木（TW）木质部中积累，但它们在 TW 形成中的生物学功能在很大程度上是未知的。在这项工作中，我们证明了杨树 TW 相关 PtFLA 之一的 PtFLA6 在 TW 中大量表达，并主要定位于分化的 G 纤维中。PtFLA6 反义转基因杨树的弯曲茎表现出 PtFLAs 的转录物减少，包括 PtFLA6 和减少的 PtFLA6 样蛋白，导致 TW 分化和形成受到抑制。我们还表明，赤霉素 A3（GA）在 TW 侧的木质部中富集，同时伴有杨树 DELLA 蛋白 PtRGA1 的水平降低。当 GA 生物合成抑制剂（daminozide）在弯曲的杨树茎中抑制 GA 生物合成时，TW 的形成明显受到抑制，这是由于 PtRGA1 降解受限，以及 PtFLA6 样蛋白和 PtFLA 表达减少。进一步的研究表明，PtFLAs 受 PtRGA1 的负调控。这项研究表明，PtFLAs 在杨树 TW 形成中发挥重要作用，可能受 GA 信号的调节。
