AUTHOR=Wang Enbo , Lu Wenju , Liang Haiying , Zhang Xumeng , Huo Shaojie , Song Xiqiang , Wang Jian , Zhao Ying 

TITLE=Morpho-histology, endogenous hormone dynamics, and transcriptome profiling in Dacrydium pectinatum during female cone development

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.954788

DOI=10.3389/fpls.2022.954788

ISSN=1664-462X

ABSTRACT=<p><italic>Dacrydium pectinatum</italic> de Laubenfels is a perennial dioeciously gymnosperm species dominant in tropical montane rain forests. Due to deforestation, natural disasters, long infancy, and poor natural regeneration ability, the population of this species has been significantly reduced and listed as an endangered protected plant. To better understand the female cone development in <italic>D. pectinatum</italic>, we examined the morphological and anatomical changes, analyzed the endogenous hormone dynamics, and profiled gene expression. The female reproductive structures were first observed in January. The morpho-histological observations suggest that the development of the <italic>D. pectinatum</italic> megaspore can be largely divided into six stages: early flower bud differentiation, bract primordium differentiation, ovule primordium differentiation, dormancy, ovule maturity, and seed maturity. The levels of gibberellins (GA), auxin (IAA), abscisic acid (ABA), and cytokinin (CTK) fluctuate during the process of female cone development. The female cones of <italic>D. pectinatum</italic> need to maintain a low level of GA<sub>3</sub>-IAA-ABA steady state to promote seed germination. The first transcriptome database for female <italic>D. pectinatum</italic> was generated, revealing 310,621 unigenes. Differential expression analyses revealed several floral (<italic>MADS2</italic>, <italic>AGL62</italic>, and <italic>LFY</italic>) and hormone biosynthesis and signal transduction (<italic>CKX</italic>, <italic>KO</italic>, <italic>KAO</italic>, <italic>ABA4</italic>, <italic>ACO</italic>, etc.) genes that could be critical for female cone development. Our study provides new insights into the cone development in <italic>D. pectinatum</italic> and the foundation for female cone induction with hormones.</p>