Transcriptome analysis of hormone-related genes in winter rapeseed treated by different photoperiods and...

Winter rapeseed is an important oilseed crop in northern China which needs to experience low temperature for a long time during the overwintering period. Come March of the next year, new leaves grow from the growing point and it enters reproductive growth. For this reason, strong winter rapeseed can only be planted once a year and it is difficult for generation acceleration breeding in field. Therefore, exploring the vernalization conditions of strong winter rapeseed in the laboratory is very helpful for shortening the growth period and improving the breeding quality.

Results showed that despite 45 days of vernalization under different light treatments, strong winter Brassica napus varieties were unable to complete the vernalization process, while other varieties achieved the optimal vernalization effect under the 16 h light/8 h dark, while strong winter Brassica rapa varieties exhibits a 75% flowering rate following 45 days of vernalization. Gibberellin A3 (GA₃) promoted flower bud differentiation in all treatments. Specifically, under 24 h dark conditions and 16 h light/8 h dark treatments, GA₃ levels were higher; furthermore, its content increased gradually as vernalization duration extended. Abscisic acid (ABA) and auxin (IAA) contents decreased progressively with prolonged vernalization under 16 h light/8 h dark treatment. Salicylic acid (SA) and zeatin (ZT) contents increased progressively with prolonged vernalization under 16 h light/8 h dark treatment. GO annotation revealed that differentially expressed genes (DEGs) were significantly enriched in terms related to cell metabolism, signal transduction, and protein-ribosome binding. KEGG pathway enrichment analysis indicated that these DEGs were primarily involved in plant-pathogen interaction, starch and sucrose metabolism, MAPK signaling pathway, and plant hormone signal transduction. Through WGCNA-based gene modular classification, combined with module expression and network analysis, one candidate gene related to plant hormone signal transduction and three candidate genes related to circadian rhythms were ultimately screened.

This study aimed to identify optimal vernalization conditions and light treatments in the laboratory, as an effective basis for subsequent breeding efforts. Meanwhile, by determining changes in hormone levels and integrating transcriptomic analysis, we analyzed the vernalization response patterns of different winter rapeseed varieties. The aim was to identify some hub genes and elucidate the molecular mechanisms underlying the vernalization process.