Brassinosteroids (BRs) play an important role in plant growth and
development. However, little is known about how BRs affect secondary wall
biosynthesis in woody plants. The team of Yun Shen from Southwest University
in China studied the brassinosteriod biosynthesis-related gene PtoDWF4 from
Chinese white poplar (Populus tomentosa).
Using CRISPE-Cas9, the team knocked-out PtoDWF4, resulting in significantly
decreased biomass production in the developed plants. Meanwhile,
overexpression of PtoDWF4 promoted growth rate and biomass yield, and
increased the area and cell layers of xylem. Overexpressing plants also
showed a significant increase in plant height and stem diameter.
Further studies revealed that expression of PtoDWF4 upregulates the
expression of secondary cell wall (SCW) biosynthesis-related genes. These
results indicate that PtoDWF4 plays a positive role in improving growth rate
and increasing biomass production in poplar.