Exploring the Seasonal Dynamics and Molecular Mechanism of Wood Formation in Gymnosperm Trees

Forests, comprising 31% of the Earth's surface, play pivotal roles in regulating the carbon, water, and energy cycles. Despite being far less diverse than angiosperms, gymnosperms account for over 50% of the global woody biomass production. To sustain growth and development, gymnosperms have evolved the capacity to sense and respond to cyclical environmental signals, such as changes in photoperiod and seasonal temperature, which initiate growth (spring and summer) and dormancy (fall and winter). Cambium, the lateral meristem responsible for wood formation, is reactivated through a complex interplay among hormonal, genetic, and epigenetic factors. Temperature signals perceived in early spring induce the synthesis of several phytohormones, including auxins, cytokinins, and gibberellins, which in turn reactivate cambium cells. Additionally, microRNA-mediated genetic and epigenetic pathways modulate cambial function. As a result, the cambium becomes active during the summer, resulting in active secondary xylem (i.e., wood) production, and starts to become inactive in autumn. This review summarizes and discusses recent findings regarding the climatic, hormonal, genetic, and epigenetic regulation of wood formation in gymnosperm trees (i.e., conifers) in response to seasonal changes.

Automated summary

Forests cover 31% of the Earth's surface and play a crucial role in regulating carbon, water, and energy cycles. Gymnosperms, despite being less diverse than angiosperms, contribute over 50% of the global woody biomass production. Gymnosperms have evolved the ability to sense and respond to cyclical environmental signals, such as changes in photoperiod and temperature, to ensure growth and development. This review summarizes recent research on the regulation of wood formation in gymnosperms (specifically conifers) in response to seasonal changes, including climatic, hormonal, genetic, and epigenetic factors.