Sucrose metabolism and candidate genes during catkin fibers development in poplar

Abstract

Poplar is an important tree species for ecological protection, wood production, landscaping and urban greening; it has been widely planted worldwide. However, the catkin fibers produced by female poplars can cause environmental pollution, human health risks and safety hazards during spring. This study focused on Populus tomentosa Carr., and reveals the sucrose metabolism regulatory mechanism of catkin fibers development from morphological, physiological and molecular aspects. And two key genes were selected to demonstrate the exact role. Sucrose degradation plays the dominant role during poplar catkin fibers development. Thereinto, invertase has a function during the early stage and sucrose synthase has a close correlation with the elongation of catkin fibers. The expression patterns revealed that sucrose metabolism-related and cellulose synthase (CesA) genes play important roles during catkin fiber development. Expression profiles and co-expression networks indicated that the mechanism underlying poplar catkin fiber development is similar, but not identical, to that of cotton fibers. Finally, two key genes, sucrose synthase 2 (PtoSUS2) and vacuolar invertase 3 (PtoVIN3), had roles in Arabidopsis thaliana trichome density, indicating that sucrose metabolism is important in poplar catkin fibers development. This study is not only helpful for clarifying the mechanism of sucrose regulation during trichome development in perennial woody plants, but also establishes a foundation to solve poplar catkin fiber pollution through biotechnology and genetic engineering methods.