Summary
Wood serves crucial functions in
plants, yet our understanding of the molecular regulation governing the
composition, arrangement, and dimensions of its cells remains limited.
The abrupt change in wood anatomy of lianas represents an excellent
model to address the underlying mechanism, although consistent
triggering factors for this process remain uncertain. In this study we
examined how physical support attachment impacts the development of
lianescent xylem anatomy 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, range of vessel sizes, broader vessel distribution, reduced fiber
content, and higher potential specific water conductivity. 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 (TFs), defense/cell death, and hormone-responsive
genes in the lianescent xylem. Based on our results, we propose a model
delineating the molecular control underlying the formation of lianescent
xylem, revealing how the increased complexity of lianescent anatomy
reflects a more intricate transcriptional regulatory network
encompassing a more diverse repertoire of TFs and hormone-responsive
genes.
Keywords: gene expression profile; lianas; transcriptome; wood;
wood traits; secondary xylem; differentiation.