Integrated transcriptomic and metabolomic analyses reveal phytohormone signaling mechanisms underlying differential regeneration potential in microspore-derived calli from hulled and hulless barley
摘要
Isolated microspore culture (IMC) is an effective model for investigating plant cell totipotency and is widely used in plant breeding programs to rapidly produce doubled haploid lines. However, the limited regeneration capacity of hulless barely restricts the broader application of IMC in breeding improvement and research.
ResultsIn this study, two hulled barley genotypes (Hua30 and L07) exhibiting high regeneration capability and two hulless barley genotypes (Zangqing2000 and Ximala22) with poor regeneration capability were selected to comparatively evaluate the regeneration potential of microspore-derived calli generated via IMC through integrated metabolomic and transcriptomic analyses. The regeneration capability of the two hulled genotypes exceeded 200 green plantlets per 100 mg microspore-derived callus, whereas that of the hulless genotypes was nearly absent. A total of 2,647 differentially expressed genes (DEGs) and 128 differentially accumulated metabolites (DAMs) were identified in microspore-derived callus from hulled genotypes relative to hulless genotypes. Integrative analysis of transcriptomic and metabolomic datasets indicated that phytohormone signaling pathways play a central role in regulating regeneration competence acquisition. Hulled barley exhibited enhanced hormonal homeostasis and comparatively lower levels of jasmonic acid (JA) and brassinosteroids (BR), which are critical determinants of regeneration capacity in microspore calli. The exogenous application of JA and BR to the induction media markedly inhibited the subsequent regeneration of plantlets in hulled barley. Several transcription factors (TFs) associated with plant regeneration, including WOX7, BBM2, and LBD, showed differential expression patterns between hulled and hulless barley, suggesting their potential functions in regulating regeneration capacity. In addition, the hulled/hulless caryopsis phenotype may be closely associated with the regeneration potential of the microspore-derived callus.
ConclusionsThese findings provide mechanistic insights into the molecular mechanisms underlying plant regeneration in barley.