Expression patterns for starch metabolism during organogenesis-like plantlet regeneration from somatic embryos of Rosa hybrida ‘J. F. Kennedy’: insights from the seed-like germination approach

In this study, single-piece cotyledonary somatic embryos (SPC explants) of Rosa hybrida ‘J. F. Kennedy’ were used as initial material, and regenerated multiple buds along the horizontal axis (RMBHA buds) derived via organogenesis-like regeneration were used as test samples. Transcriptome sequencing was performed to analyze the expression patterns of genes involved in starch aerobic decomposition metabolism (starch hydrolysis, glycolysis, and the tricarboxylic acid cycle (TCA cycle). A total of 60 differentially expressed genes (DEGs) (42 down-regulated, 18 up-regulated) related to starch aerobic decomposition metabolism were identified in the RMBHA vs. SPC comparison group. Key genes involved in starch hydrolysis ( ISA3 , α-AMYs , BAM3s , and AGIs ) were upregulated in RMBHA buds, while glycolysis-related genes ( HXK1 , PFKs , PKs , GPIs , GAPDHs , and PGK ) were upregulated in SPC explants, and TCA cycle-related genes ( CSs , IDH , α-KGDH , and FH1 ) showed differential expression patterns. Compared with the seed-like germination approach (the GER approach), in the organogenesis-like regeneration approach (the OR approach), 13 starch hydrolysis-related DEGs were identified, and 18 TCA cycle-related genes were up-regulated in somatic embryo cells; in the GER approach, the corresponding numbers were 9 and 14, respectively. These findings indicate that while both regeneration approaches share common energy metabolic features—starch hydrolysis more active in regenerated tissues and glycolysis more active in somatic embryo cells—the OR approach may be associated with a greater need for glucose mobilization and may involve different carbon allocation strategies, possibly reflecting differences in energy and metabolic demands of multiple bud formation. This study provides new insights into the metabolic flexibility underlying different regeneration programs from the same somatic embryo material.