International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.2, 111-123 http://ecoevopublisher.com/index.php/ijmeb 115 5 Molecular Regulatory Mechanisms of Flowering and Seed Development 5.1 Multi-level regulatory network of flowering time The initiation of flowering time often originates from the synergistic accumulation of photoperiod and hormone levels in plants. Once these signals reach a certain critical point, the plant's "developmental clock" begins to count down. For example, WRKY184 is an important transcription factor that controls flowering initiation by regulating key genes such as FT and LFY (Yang et al., 2020). Genome-wide association analysis also identified 12 stable QTL hotspots, three of which are highly homologous to known flowering-related genes in Arabidopsis (Li et al., 2018). In addition, epigenetic modifications also add a temporal regulatory dimension to flowering regulation. For example, during the vernalization stage, the promoter regions of some genes that inhibit flowering show gradually enhanced DNA methylation, which eventually releases the inhibition of flowering, thereby completing a transitional developmental transition (Schiessl et al., 2014). 5.2 Genetic regulatory program of seed development In the early stage of embryonic development, the transcription factor BZIP11 plays the role of a "master control center". Once its function is lost, the embryo will not be able to successfully pass the spherical stage, and the development process will be terminated (Khan et al., 2021). Entering the middle stage of development, the expression of fatty acid synthesis-related genes in seeds is significantly enhanced, and its expression level can be increased by more than 50 times (Niu et al., 2009). miR394 plays the role of a "quality regulator" in this process. It selectively inhibits enzyme genes with low synthesis efficiency, thereby improving the overall efficiency of lipid accumulation (Song et al., 2015). At the same time, the regulatory module composed of WRI1 and LAFL family members has a significant effect on oil content, and the expression levels of the two are highly positively correlated with oil accumulation (r = 0.82, P< 0.01) (Han et al., 2024). 5.3 Integration of hormone signaling and developmental regulation During flowering and seed development, changes in hormone signaling play a decisive role. The mutual balance between gibberellins and ethylene constructs a fine regulatory network. The BnaBPs gene family regulates the biosynthesis of the two hormones to ensure that their concentrations are maintained within an appropriate range (Yu et al., 2024). On the other hand, during the seed formation stage, the distribution of auxin forms a significant concentration gradient. The auxin level inside the embryo is three to five times higher than that in the surrounding tissues. This difference effectively guides the orderly distribution of storage substances such as fatty acids (Niu et al., 2009). Under adversity, the ABA signaling pathway is activated, which not only delays flowering, but also helps plants accumulate more resources for the future. These signaling pathways are intertwined with the gene regulatory network to jointly establish a complex regulatory system that can dynamically respond to environmental changes and ensure the success of plant growth and reproduction. 6 Molecular Regulatory Network of Abiotic Stress Response 6.1 Molecular adaptation mechanism of drought stress When rapeseed encounters water stress, it will quickly activate a set of emergency response mechanisms to maintain life activities. The first to be activated is the ABA (abscisic acid) signaling pathway, which can cause stomatal closure in just 30 minutes, thereby significantly reducing water evaporation (Chen et al., 2010). At the same time, NDPK family genes are upregulated, like a biological alarm system, effectively transmitting stress signals (Wang et al., 2024). Among them, BnSIP1-1 is particularly significant. It not only enhances the synthesis capacity of ABA, but also promotes the transmission of downstream signals, and the survival rate of transgenic lines is therefore increased by about 60% (Luo et al., 2017). From a metabolic perspective, the content of proline isotonic regulatory molecules increases significantly under drought conditions, usually 8 to 10 times that of normal conditions. This type of substance builds an effective physiological protection barrier by maintaining cell osmotic pressure and stabilizing protein structure. 6.2 Response network of temperature stress Extreme climate poses severe challenges to rapeseed, whether it is high temperature or low temperature. Under heat stress, plants will quickly adjust transcriptional activity - the expression levels of more than 1,200 genes are
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