Tree Genetics and Molecular Breeding 2025, Vol.15, No.1, 1-8 http://genbreedpublisher.com/index.php/tgmb 2 The interplay between these hormones determines the overall architecture of the durian tree, affecting branching patterns, canopy density, and ultimately fruit-bearing capacity. In fruit development, auxin promotes ovary expansion and fruit set, while cytokinin plays a role in nutrient allocation and fruit size determination. A deeper understanding of auxin and cytokinin interactions will provide new insights into improving tree growth regulation and optimizing fruit yield in durian (Suntichaikamolkul et al., 2021). Despite the recognized importance of auxin and cytokinin in plant growth, their specific regulatory mechanisms in durian remain largely unexplored. This research aims to investigate the genetic basis of tree size and fruit yield by focusing on auxin and cytokinin signaling pathways. By identifying key genes involved in hormonal regulation, we can develop strategies to modulate tree architecture and improve yield efficiency. Recent advances in durian genomics, transcriptomics, and functional studies provide an opportunity to dissect the molecular interactions between auxin and cytokinin, leading to potential applications in precision breeding. This research will contribute to a better understanding of durian’s growth dynamics and offer new approaches to optimizing its cultivation through genetic and hormonal interventions. 2 Genetic Regulation of Tree Size in Durian 2.1 Key genes involved in tree height and canopy development The genetic factors controlling durian tree size are linked to several key genes that influence height and canopy growth. While specific genes directly affecting tree height in durian remain under investigation, transcription factors such as Dof proteins, known for their role in various plant growth processes, present promising candidates. These proteins regulate auxin biosynthesis, which is essential for plant development and plays a key role in determining tree size (He et al., 2018). 2.2 Influence of auxin signaling pathway on tree morphology Auxin is a crucial plant hormone that significantly affects tree morphology, including height and canopy structure. In durian, auxin signaling is mediated by auxin response factors (ARFs), such as DzARF2A, which have been identified for their role in fruit ripening via ethylene biosynthesis regulation (Liu et al., 2018a). Although auxin’s direct effects on durian tree morphology remain unclear, its well-documented influence on plant growth suggests it plays an important role in shaping tree structure (Liu et al., 2018b). 2.3 Role of cytokinin in shoot differentiation and growth Cytokinin is another essential phytohormone that regulates shoot differentiation and overall tree growth. While specific data on cytokinin’s role in durian tree development is limited, its well-established function in promoting cell division and shoot formation in other plants highlights its significance in determining tree architecture (He and Yamamuro, 2022). The dynamic interaction between cytokinin and auxin is critical for balancing root and shoot growth, ultimately influencing tree size and productivity. 2.4 Interaction between auxin and cytokinin in tree development The interplay between auxin and cytokinin is a fundamental aspect of plant development, affecting multiple growth processes. In durian, auxin-ethylene crosstalk, regulated by DzARF2A, demonstrates the complex hormonal interactions that drive growth and structural changes. Although specific auxin-cytokinin interactions in durian tree development remain underexplored, their well-established synergistic and antagonistic relationships in other plant species suggest that similar regulatory mechanisms may influence durian tree morphology (Reyes-Olalde et al., 2017). Understanding these interactions will provide valuable insights for optimizing durian tree architecture and improving orchard management strategies. 3 Genetic Control of Fruit Yield in Durian 3.1 Genetic regulatory mechanisms affecting flowering and fruiting The regulation of flowering and fruiting in durian is influenced by complex interactions between plant hormones and transcription factors. Auxin response factors (ARFs) play a critical role in fruit development and ripening by acting as key regulators in hormone-dependent pathways, impacting fruit size, yield, and quality. Additionally, MADS-box transcription factors are involved in modulating cytokinin levels, which are essential for fruit growth
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