Comparative transcriptomics and WGCNA reveal candidate genes involved in petaloid stamens in Paeonia lactiflora

Petaloid stamens in Paeonia lactiflora constitute an important developmental phenomenon that explain double flower formation. Although research on stamen development in model plants has progressed considerably, the underlying molecular mechanism in P. lactiflora petaloid stamens is still unclear. In this study, acomparative transcriptomic analysis was performed on two cultivars of P. lactiflora ('Fen Yu Nu' and 'Lian Tai') with different stamen developmental patterns. Following transcriptome sequencing, 89,393 unigenes were identified in P. lactiflora. Trend analysis and weighted gene co-expression network analysis (WGCNA) indicated that 18 candidate genes were likely involved in the formation and development of petaloid stamens, including seven MADS-box genes, PlAP3, PlDEFA, PlPI2, PlAG-1, PlSEP3, PlSEP1-1, and PlSEP1-2, and 11 other transcription factors (TFs), PlTCP2, PlTCP4, PlTCP9, PlbHLH36, PlICE1, PlLBD38, PlNAC083, PlBLH11, PlPDF2, PlGBF1, and PlIIIA. Using these 18 selected candidate genes, we propose ahypothetical model of gene expression network that regulates the development of petaloid stamens. Our results provide acollection of candidate genes that are useful for the analysis of P. lactiflora petaloid stamens, allowing for in-depth studies of the development pattern of P. lactiflora flower organs, and providing atheoretical basis for related research on petaloid stamens of flowers in other herbaceous plants.