Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
Plant Cell Environ. 2024 Dec;47(12):5172-5188. doi: 10.1111/pce.15094. Epub 2024 Aug 22.
Wood serves crucial functions in plants, yet our understanding of the mechanisms governing the composition, arrangement, and dimensions of its cells remains limited. The abrupt transition from nonlianescent to lianescent xylem in lianas represents an excellent model to address the underlying mechanisms, although consistent triggering factors for this process remain uncertain. In this study we examined how physical support attachment impacts the development of lianescent xylem in Bignonia magnifica (Bignoniaceae), employing a comprehensive approach integrating detailed anatomical analysis with gene expression profiling of cambium and differentiating xylem. Our findings demonstrate that attachment to physical supports triggers the formation of lianescent xylem, leading to increased vessel size, broader vessel distribution, reduced fibre content, and higher potential specific water conductivity than nonlianescent xylem. These shifts in wood anatomy coincide with the downregulation of genes associated with cell division and cell wall biosynthesis, and the upregulation of transcription factors, defense/cell death, and hormone-responsive genes in the lianescent xylem. Our findings provide insights into the regulation of xylem differentiation, driven by response to environmental stimuli. Additionally, they shed light on the mechanisms underlying the adaptation of lianas to climbing.
木材在植物中起着至关重要的作用，但我们对控制其细胞组成、排列和尺寸的机制的理解仍然有限。木质部从非藤本到藤本的突然转变为研究这一潜在机制提供了一个极好的模型，尽管这一过程的一致触发因素仍不确定。在这项研究中，我们通过整合详细的解剖学分析和形成层及分化木质部的基因表达谱，研究了物理支撑物附着如何影响美丽凌霄（紫葳科）藤本木质部的发育。研究结果表明，附着于物理支撑物会触发藤本木质部的形成，导致导管尺寸增大、导管分布变宽、纤维含量减少、潜在比导率增加，这些变化与与细胞分裂和细胞壁生物合成相关的基因下调，以及转录因子、防御/细胞死亡和激素响应基因在藤本木质部中的上调有关。我们的研究结果为环境刺激驱动的木质部分化调控提供了新的见解，同时也揭示了藤本植物适应攀援的机制。
