Comparative Transcriptomic Analysis Provides Insight Into Carpel Petaloid in Lotus (Nelumbo Nucifera)

Abstract Background: Lotus (Nelumbo nucifera) is a famous flower with high ornamental value. Flower color and flower morphology are two main factors for flower lotus breeding. Petaloid is a universal phenomenon in lotus flowers. However, the genetic regulation of floral organ petaloid in lotus still remains unclear. Results: In this study, the transcriptomic analysis was performed among five organs, including petal, stamen petaloid, stamen, carpel petaloid, and carpel in lotus. 812 annotated DEGs related to carpel petaloid were identified. Our study showed that DNA methylation may be involved in regulating carpel petaloid. To identify the patterns of gene expression in the petaloid process using WGCNA analysis, 37 candidate genes were found to be related to carpel petaloid. Additionally, one floral homeotic gene encoded by MADS box transcription factor, AGAMOUS (AG), was identified as the candidate gene for petaloid in lotus. Meanwhile, a predicted labile boundary in floral organs of N. nucifera was hypothesized. Conclusions: In summary, the above results explored the candidate genes related to carpel petaloid, setting a theoretical basis for the molecular regulation of petaloid phenotype.