Elucidation of molecular and hormonal background of early growth cessation and endodormancy induction in two contrasting Populus hybrid cultivars

Interaction of Phytohormones and External Environmental Factors in the Regulation of the Bud Dormancy in Woody Plants

Bud dormancy and release are essential phenomena that greatly assist in adapting to adverse growing conditions and promoting the holistic growth and development of perennial plants. The dormancy and release process of buds in temperate perennial trees involves complex interactions between physiological and biochemical processes influenced by various environmental factors, representing a meticulously orchestrated life cycle. In this review, we summarize the role of phytohormones and their crosstalk in the establishment and release of bud dormancy. External environmental factors, such as light and temperature, play a crucial role in regulating bud germination. We also highlight the mechanisms of how light and temperature are involved in the regulation of bud dormancy by modulating phytohormones. Moreover, the role of nutrient factors, including sugar, in regulating bud dormancy is also discussed. This review provides a foundation for enhancing our understanding of plant growth and development patterns, fostering agricultural production, and exploring plant adaptive responses to adversity.

Transcriptomic Analysis Reveals the Positive Role of Abscisic Acid in Endodormancy Maintenance of Leaf Buds of Magnolia wufengensis

Magnolia wufengensis (Magnoliaceae) is a deciduous landscape species, known for its ornamental value with uniquely shaped and coloured tepals. The species has been introduced to many cities in south China, but low temperatures limit the expansion of this species in cold regions. Bud dormancy is critical for plants to survive in cold environments during the winter. In this study, we performed transcriptomic analysis of leaf buds using RNA sequencing and compared their gene expression during endodormancy, endodormancy release, and ecodormancy. A total of 187,406 unigenes were generated with an average length of 621.82 bp (N50 = 895 bp). In the transcriptomic analysis, differentially expressed genes involved in metabolism and signal transduction of hormones especially abscisic acid (ABA) were substantially annotated during dormancy transition. Our results showed that ABA at a concentration of 100 μM promoted dormancy maintenance in buds of M. wufengensis. Furthermore, the expression of genes related to ABA biosynthesis, catabolism, and signalling pathway was analysed by qPCR. We found that the expression of MwCYP707A-1-2 was consistent with ABA content and the dormancy transition phase, indicating that MwCYP707A-1-2 played a role in endodormancy release. In addition, the upregulation of MwCBF1 during dormancy release highlighted the enhancement of cold resistance. This study provides new insights into the cold tolerance of M. wufengensis in the winter from bud dormancy based on RNA-sequencing and offers fundamental data for further research on breeding improvement of M. wufengensis.