It is a debate whether trunk twisting belongs to environmental alteration or genetic variation. Through a diallel cross experiment, we first determined that trunk twisting of Yunnan pines was controlled by recessive genes. Anatomical analysis identified that straight and twisty types differed in xylem and phloem. RNA-seq of materials enriched by laser microdissection revealed three genes involved in auxin signal transduction, photosynthesis, and sucrose metabolism, namely ARF, POR, and CBH. These genes were co-expressed at different growth stages of twisty types, and among them, ARF is crucial regulating trunk twisting formation. The enzyme activities involved in sucrose metabolism, carbon fixation, and glycolysis were significantly increased after exogenous auxin was added to twisty types. When auxin signal transduction inhibitor (auxinole) and transport inhibitor (TIBA) were added, the plant height and related pathways were more obviously reduced in straight types. ARF can not only downregulate POR to block chlorophyll synthesis but also allows abundant sucrose to synthesize cellulose. Nevertheless, due to downregulated CBH expression and abnormal cellulolysis, cellulose accumulates and the lignin content decreases, eventually making the trunk highly prone to twisted growth. This study suggests that ARF can be vital in trunk shape screening during the early growth of Yunnan pines.

Ancient Pu’er tea trees (Camellia sinensis var. assamica (J. W. Mast.) Kitam.) are an important ecological resource with high economic value. Knowledge of the environmental variables shaping the original distribution and the effects of climate change on the future potential distribution of these trees, as well as the identification of sustainable management approaches, is essential for ensuring their future health and production. Here, we used 28 current environmental variables and the future climate data to model the suitable areas for ancient Pu’er tea trees. We also compared the health of these ancient trees in areas under different local management strategies. The results suggested the general distribution is likely to remain stable, but there are environmentally suitable areas outside its current habitats. To achieve more sustainable management, the main areas in which the management of poorly-managed trees can be improved include learning from managers of well-managed trees and following the common technical management regulations stipulated by the local government. The suitable value ranges for environmental factors, potentially suitable areas under climate change, and assessment of management approaches will aid the future cultivation and transplantation of ancient Pu’er tea trees. The methodology includes management-level analysis and provides practical insights that could be applied to regions outside the most suitable areas identified.