Tree Genetics and Molecular Breeding 2024, Vol.14, No.4, 166-176 http://genbreedpublisher.com/index.php/tgmb 171 and strigolactones are key hormones involved in long-distance signaling that regulate cambium activity and secondary growth (Agustí et al., 2011). Additionally, reactive oxygen species (ROS) and other signaling molecules are integrated with pathways involving Ca2+ signaling, protein kinases, and hormones to modulate defense mechanisms and stress responses (Suzuki and Katano, 2018). The integration of long-distance signals with local regulatory networks ensures coherent growth and development across the entire plant. Figure 3 Schematic representation of phloem-mobile signals in plants (mRNAs, RBPs, sRNAs, and proteins) (Adopted from Kondhare et al., 2021) Image caption: Grouped by their functions in growth, development, and biotic/abiotic stress responses (Adopted from Kondhare et al., 2021) 6 Ecosystem Level Regulation 6.1 Impact of biotic factors on stem cells Biotic factors, including symbiotic relationships, play a crucial role in the regulation of tree stem cells. Symbiotic fungi, for instance, form mutualistic associations with tree roots, enhancing nutrient uptake and promoting stem cell activity and growth. These interactions are essential for maintaining the health and functionality of forest ecosystems. The complexity of trophic networks and biotic associations significantly influences ecosystem multifunctionality, as demonstrated in subalpine forests where species richness across multiple trophic levels enhances ecosystem functions (Luo et al., 2022). Additionally, plant growth regulators (PGRs) are involved in plant-plant communications and defense mechanisms against biotic stress, further influencing stem cell behavior and tree resilience (Johnson, 1987). 6.2 Influence of abiotic factors on stem cell function Abiotic factors such as climate, soil properties, and environmental stressors have profound effects on the function and regulation of tree stem cells. For instance, temperature, water availability, and soil nutrients directly impact the physiological processes of trees, including stem cell activity. Long non-coding RNAs (lncRNAs) and MYB transcription factors are key molecular players that help plants adapt to abiotic stresses like drought, salinity, and temperature extremes by regulating stress-responsive genes (Jha et al., 2020; Wang et al., 2021). Furthermore, the synthesis of cellulose, a critical component of plant cell walls, is influenced by abiotic factors such as osmotic conditions, ionic stress, light, and temperature, which in turn affects overall plant growth and stem cell function (Wang et al., 2016). The interplay between plant functional traits and abiotic site conditions also mediates
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