Key Laboratory of Bamboo and Rattan Science and Technology, State Forestry Administration, Institute of Horticultural Flower and Landscape, International Center for Bamboo and Rattan, Futongdong Rd, Wang Jing, Chaoyang District, Beijing, 100102, China.
Sci Rep. 2022 Oct 14;12(1):17281. doi: 10.1038/s41598-022-22195-z.
Paeonia × lemoinei 'High Noon' is one of the most important cultivars in tree peony (Paeonia sect. Moutan), a traditional horticultural plant in China, with a re-blooming characteristic which was quite different from other cultivars. So, the genetic resources in 'High Noon' were incredibly valuable in flowering-time-modified molecular breeding in tree peony. However, the molecular mechanism underlying the floral bud formation of 'High Noon' was not clear yet. To explore the molecular mechanism in this process, the transcriptomes of three stages during floral bud development were deeply analyzed in this study. As a result, a total of 5816 differentially expressed genes (DEGs) were identified between the three developmental stages, and pathways including ''DNA replication'', ''metabolic pathways'', ''circadian rhythm'', and ''plant hormone signal transduction'' were mostly enriched in the functional enrichment and expression pattern analysis. Furthermore, a total of 584 genes related to the photoperiod pathway were further identified and a novel CO homolog gene PlCO was identified to be a stable hydrophilic protein, which contained both CCT domain and B-box domain. Over-expression of PlCO in Arabidopsis resulted in early flowering, which suggested a promotion role of flowering. The PlCO protein localized in nucleus and possessed a transcription activity ability, which implied that PlCO might function as a transcription factor. The transcriptome analysis revealed pathways involved in floral bud development in tree peony and provided new insight into the regulatory network underlying the floral bud development. The gene identification in 'High Noon' provided new valuable candidate genes for flowering-time-modified molecular breeding in tree peony.
牡丹 'High Noon' 是芍药属牡丹组中最重要的品种之一，是中国传统园艺植物，具有重瓣开花的特性，与其他品种有很大的不同。因此，'High Noon' 的遗传资源在牡丹开花时间的分子改良育种中具有极高的价值。然而，'High Noon' 花芽形成的分子机制尚不清楚。为了探索这一过程中的分子机制，本研究对花芽发育的三个阶段进行了深入的转录组分析。结果共鉴定出 5816 个差异表达基因（DEGs），在功能富集和表达模式分析中，主要富集了“DNA 复制”、“代谢途径”、“昼夜节律”和“植物激素信号转导”等途径。此外，还进一步鉴定了 584 个与光周期途径相关的基因，并鉴定出一个新的 CO 同源基因 PlCO，它是一种稳定的亲水蛋白，含有 CCT 结构域和 B-box 结构域。拟南芥中 PlCO 的过表达导致早花，表明其对开花具有促进作用。PlCO 蛋白定位于细胞核，具有转录活性，表明 PlCO 可能作为转录因子发挥作用。转录组分析揭示了牡丹花芽发育过程中涉及的途径，并为花芽发育的调控网络提供了新的见解。'High Noon' 中的基因鉴定为牡丹开花时间的分子改良育种提供了新的有价值的候选基因。
