Transcription Profiles Reveal Sugar and Hormone Signaling Pathways Mediating Flower Induction in Apple (Malus domesticaBorkh.)

Abstract

Flower induction in apple (Malus domestica Borkh.) is regulated by complex gene networks that involve multiple signal pathways to ensure flower bud formation in the next year, but the molecular determinants of apple flower induction are still unknown. In this research, transcriptomic profiles from differentiating buds allowed us to identify genes potentially involved in signaling pathways that mediate the regulatory mechanisms of flower induction. A hypothetical model for this regulatory mechanism was obtained by analysis of the available transcriptomic data, suggesting that sugar-, hormone- and flowering-related genes, as well as those involved in cell-cycle induction, participated in the apple flower induction process. Sugar levels and metabolism-related gene expression profiles revealed that sucrose is the initiation signal in flower induction. Complex hormone regulatory networks involved in cytokinin (CK), abscisic acid (ABA) and gibberellic acid pathways also induce apple flower formation. CK plays a key role in the regulation of cell formation and differentiation, and in affecting flowering-related gene expression levels during these processes. Meanwhile, ABA levels and ABA-related gene expression levels gradually increased, as did those of sugar metabolism-related genes, in developing buds, indicating that ABA signals regulate apple flower induction by participating in the sugar-mediated flowering pathway. Furthermore, changes in sugar and starch deposition levels in buds can be affected by ABA content and the expression of the genes involved in the ABA signaling pathway. Thus, multiple pathways, which are mainly mediated by crosstalk between sugar and hormone signals, regulate the molecular network involved in bud growth and flower induction in apple trees.

Identification and Characterization of miRNAs in Self-Rooted and Grafted Malus Reveals Critical Networks Associated with Flowering

“…Previous studies have shown that endogenous hormones, nucleic acids, carbohydrates, and proteins also affect flower induction. Leaves are the main organs for producing nutrients in the plant and are the main source of nutrients for flower induction [29,30,31]. In the present study, we found significant differences in fresh weight, dry weight, and leaf area among the three materials, indicating that these attributes were affected by grafting.…”

Identification and Expression Analysis of Polygalacturonase Family Members during Peach Fruit Softening

“…The experiment was repeated three times. The detailed methods of raw fastq files handling from RNA-seq were carried out according to Xing [68]. …”

Identification, Classification, and Expression Analysis of GRAS Gene Family in Malus domestica

“…Flower induction was affected by environmental and internal factors (Guitton et al, 2012; Xing et al, 2014, 2015; Fan et al, 2016). Sugar and hormones were involved in flower induction (Guitton et al, 2012; Xing et al, 2014, 2015; Fan et al, 2016; Li et al, 2016; Zhang et al, 2016). Among all kinds of hormones, including auxin, cytokinins, abscisic acid, GA and other hormones.…”

“…GA was defined the most important hormones in regulating flower induction and GA pathway was recognized as one of the flowering pathways (Guitton et al, 2012; Porri et al, 2012; Li et al, 2016; Zhang et al, 2016). 6-BA and sucrose, which can promote flower bud differentiation, were also important and widely used (Xing et al, 2015; Li et al, 2016). Several flowering-related genes families have been identified and characterized in the apple genome, including SPL, IDD , and MADX-box (Li et al, 2013; Kumar et al, 2016; Fan et al, 2017).…”