Genome-Wide Identified MADS-Box Genes in Prunus campanulata ‘Plena’ and Theirs Roles in Double-Flower Development

Abstract

The MADS-box gene family plays key roles in flower induction, floral initiation, and floral morphogenesis in flowering plants. To understand their functions in the double-flower formation of Prunus campanulata ‘Plena’ (hereafter referred to as PCP), which is an excellent flowering cherry cultivar, we performed genome-wide identification of the MADS-box gene family. In this study, 71 MADS-box genes were identified and grouped into the Mα, Mβ, Mγ and MIKC subfamilies according to their structures and phylogenetic relationships. All 71 MADS-box genes were located on eight chromosomes of PCP. Analysis of the cis-acting elements in the promoter region of MADS-box genes indicated that they were associated mainly with auxin, abscisic acid, gibberellin, MeJA (methyl jasmonate), and salicylic acid responsiveness, which may be involved in floral development and differentiation. By observing the floral organ phenotype, we found that the double-flower phenotype of PCP originated from petaloid stamens. The analysis of MIKC-type MADS-box genes in PCP vegetative and floral organs by qRT–PCR revealed six upregulated genes involved in petal development and three downregulated genes participating in stamen identity. Comparative analysis of petaloid stamens and normal stamens also indicated that the expression level of the AG gene (PcMADS40) was significantly reduced. Thus, we speculated that these upregulated and downregulated genes, especially PcMADS40, may lead to petaloid stamen formation and thus double flowers. This study lays a theoretical foundation for MADS-box gene identification and classification and studying the molecular mechanism underlying double flowers in other ornamental plants.

Transcriptomics analyses reveal the key genes involved in stamen petaloid formation in Alcea rosea L.

“…Gibberellin promotes stamen development in A. thaliana by promoting the expression of MYB TFs, which are controlled by jasmonic acid [74]. The gibberellin, abscisic acid, salicylic acid, and methyl jasmonate (MeJA) signaling pathways may interact with cis-acting elements in the promoter region of the MADS-box gene to regulate stamen and petal development [34,75]. Studies have shown that ethylene is critical in determining plant reproductive organs.…”

“…Whereas on the other hand, phytohormones can affect the growth and development of floral organs by regulating the expression of genes in their signal transduction and synthesis pathways [32][33][34]. For example, auxin regulates the expression of AUX/IAA, ARF, and GH3, thereby affecting cell expansion and division, cell elongation and differentiation, and various physiological responses [32].…”

“…In addition to regulating their own signaling pathways, plant hormones may also regulate the expression of other genes related to flower development. Analysis of the cisacting elements in the promoter region of MADS-box genes in Prunus campanulata 'Plena' showed that auxin, abscisic acid, gibberellin, methyl jasmonate, and salicylic acid regulate the transcriptional expression of MADSbox genes, which in turn affects floral development and differentiation [34]. Currently, most published studies related to plant hormones have focused on seed germination and dormancy, flower bud differentiation, and floral regulation [35,36], but the hormone signaling pathways associated with stamen petaloid development still need to be explored in depth.…”