Temporal and Spatial Characteristics Endogenous Hormone Regulation During Male Cone Development of Dacrydium pectinatum

Background: Dacrydiumpectinatum de Laubenfels is a perennial gymnosperm dominant in tropical montane rain forests. Due to severe damages by excessive deforestation, typhoons, and other external forces, the population of the species has been significantly reduced. Furthermore, natural regeneration is poor. In order to better understand the reproductive process in D. pectinatum , we examined the morphological and anatomical changes during the development of male cone and analyzed the endogenous hormone dynamics. Results: : Our study indicates that D. pectinatum male buds become distinguishable in April in tropical montane rain forests, while microspore sac forms in September and pollen mother cell forms and divides in December. Pollen grains mature and disperse in the following February. A mature male cone averages 8.5 mm in length. Level of GA, IAA, ABA and JA and their ratios fluctuated during late August to late November when sporogenous tissues were actively differentiated. Conclusions: : The differentiation of sporogenous tissues is accompanied by variations in levels of endogenous hormones (GA, ABA, IAA, and JA) and their balances. The new insights about the cone development in D. pectinatum lay the foundation for future cone induction with hormones and study of factors contributing to the species’ low rate of seed germination.