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Review
. 2019 Nov 15;10:1474.
doi: 10.3389/fpls.2019.01474. eCollection 2019.

Dissecting the Function of MADS-Box Transcription Factors in Orchid Reproductive Development

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Free PMC article
Review

Dissecting the Function of MADS-Box Transcription Factors in Orchid Reproductive Development

Zhi Wei Norman Teo et al. Front Plant Sci. .
Free PMC article

Abstract

The orchid family (Orchidaceae) represents the second largest angiosperm family, having over 900 genera and 27,000 species in almost all over the world. Orchids have evolved a myriad of intriguing ways in order to survive extreme weather conditions, acquire nutrients, and attract pollinators for reproduction. The family of MADS-box transcriptional factors have been shown to be involved in the control of many developmental processes and responses to environmental stresses in eukaryotes. Several findings in different orchid species have elucidated that MADS-box genes play critical roles in the orchid growth and development. An in-depth understanding of their ecological adaptation will help to generate more interest among breeders and produce novel varieties for the floriculture industry. In this review, we summarize recent findings of MADS-box transcription factors in regulating various growth and developmental processes in orchids, in particular, the floral transition and floral patterning. We further discuss the prospects for the future directions in light of new genome resources and gene editing technologies that could be applied in orchid research and breeding.

Keywords: MADS-box transcription factors; development; floral patterning; floral transition; orchid.

Figures

Figure 1
Figure 1
Function of MADS-box proteins in the whole plant life cycle. (A) MADS-box genes regulate Arabidopsis development throughout its life cycle. Many MADS-box genes mediate the transition to flowering. The flowering time repressor genes, including FLC (Michaels and Amasino, 1999), FLM (Ratcliffe et al., 2001), MAF2-5 (Ratcliffe et al., 2003; Gu et al., 2013), SVP (Hartmann et al., 2000; Li et al., 2008), and AGL15/18 (Adamczyk et al., 2007), are shown in red color, whereas the flowering time promoter genes, including SOC1 (Lee et al., 2000), AGL24 (Yu et al., 2002), AGL6 (Yoo et al., 2011), XAL1/AGL12 (Tapia-Lopez et al., 2008), AGL17 (Han et al., 2008), AGL19 (Schonrock et al., 2006), AGL28 (Yoo et al., 2006), and AGL42/71/72 (Dorca-Fornell et al., 2011), are shown in green color. All the identified floral organ identity genes except AP2 encode MADS-box transcription factors. MADS-box genes are also involved in root growth (e.g. XAL1, XAL2, AGL21, ANR1, SHP1,2, and STK) (Zhang and Forde, 1998; Tapia-Lopez et al., 2008; Moreno-Risueno et al., 2010; Garay-Arroyo et al., 2013; Yu et al., 2014), vegetative growth (e.g. AGL16’s function in stomata development) (Kutter et al., 2007), pollen maturation and tube growth (AGL65/66/104) (Adamczyk and Fernandez, 2009), ovule development (e.g. AGL13, AGL23, AGL62, SHP1,2 and STK) (Liljegren et al., 2000; Pinyopich et al., 2003; Colombo et al., 2008; Kang et al., 2008; Hsu et al., 2014), and embryo and seed development (e.g. DIA, AGL80, AGL23, and PHE1) (Kohler et al., 2003; Portereiko et al., 2006; Bemer et al., 2008; Colombo et al., 2008). (B) Functions of MADS-box genes in orchid development. Orchid MADS-box proteins have been shown to regulate flowering and floral organ formation. AG, AGAMOUS; AGL6, AGAMOUS-LIKE 6; AGL15, AGAMOUS-LIKE 15; AGL16, AGAMOUS-LIKE 16; AGL17, AGAMOUS-LIKE 17; AGL18, AGAMOUS-LIKE 18; AGL19, AGAMOUS-LIKE 19; AGL21, AGAMOUS-LIKE 21; AGL23, AGAMOUS-LIKE 23; AGL24, AGAMOUS-LIKE 24; AGL28, AGAMOUS-LIKE 28; AGL42, AGAMOUS-LIKE 42; AGL65, AGAMOUS-LIKE 65; AGL66, AGAMOUS-LIKE 66; AGL71, AGAMOUS-LIKE 71; AGL72, AGAMOUS-LIKE 72; AGL80, AGAMOUS-LIKE 80; AGL104, AGAMOUS-LIKE 104; ANR1, ARABIDOPSIS NITRATE REGULATED 1; AP1, APETALA1; AP3, APETALA3; CAL, CAULIFLOWER; CO, CONSTANS; DIA, DIANA; FLC, FLOWERING LOCUS C; FLM, FLOWERING LOCUS M; FT, FLOWERING LOCUS T; FUL, FRUITFULL; MAF2-5, MADS AFFECTING FLOWERING 2-5; PHE1, PHERES1; PI, PISTILLATA; SEP1-4, SEPALLATA1-4; SHP1,2, SHATTERPROOF1,2; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1; STK, SEEDSTICK; SVP, SHORT VEGETATIVE PHASE; XAL1, XAANTAL 1; XAL2, XAANTAL 2.
Figure 2
Figure 2
Biological roles of MADS-box genes in controlling flowering in the model plant Arabidopsis and orchid. In Arabidopsis, the MADS-box genes including SOC1, FLC, SVP and AGL24 integrates signals for flowering from environmental and endogenous cues. In orchid, orthologous genes of SOC1, AGL6, SVP, and AP1 have been isolated and functionally characterized either in heterologous system (e.g. Arabidopsis) or orchid and shown to be involved in promoting flowering. MADS-box transcription factors that function as flowering activators and suppressors are shown in green and red, respectively, whereas other flowering regulators are shown in black. Promoting and repressive effects are indicated by black arrows and orange T bars, respectively. The dashed lines with arrows indicate possible positive regulation based on the studies using heterologous systems. Double-ended diamond arrows indicate protein–protein interactions. AGL6, AGAMOUS-LIKE 6; AGL17, AGAMOUS-LIKE 17; AGL19, AGAMOUS-LIKE 19; AGL24, AGAMOUS-LIKE 24; AP1, APETALA1; CO, CONSTANS; FLC, FLOWERING LOCUS C; FLM, FLOWERING LOCUS M; FT, FLOWERING LOCUS T; FTIP1, FT-INTERACTING PROTEIN 1; FUL, FRUITFULL; LFY, LEAFY; MAF2, MADS AFFECTING FLOWERING 2; SOC1, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1; SVP, SHORT VEGETATIVE PHASE.
Figure 3
Figure 3
Floral organ identity genes in orchid. (A) An illustration showing a typical orchid flower structure. (B) Expression patterns of orthologs of floral organ identity genes in orchid. The floral organs, sepal, petal, lip, stamen, carpel, and leaf are color-coded, and presence of these colors indicates detected expression in these organs. The white color indicates no expression detected. The gene expression patterns are shown based on the studies in the Oncidium orchid (Chang et al., 2009; Chang et al., 2010; Hsu et al., 2010; Hsu et al., 2015).
Figure 4
Figure 4
Schematic drawing showing the ABCE model (A), the modified ABC model (B), and the orchid Perianth code (C).

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References

    1. Aceto S., Gaudio L. (2011). The MADS and the beauty: genes involved in the development of orchid flowers. Curr. Genomics 12, 342–356. 10.2174/138920211796429754 - DOI - PMC - PubMed
    1. Acri-Nunes-Miranda R., Mondragón Palomino M. (2014). Expression of paralogous SEP-, FUL-, AG-and STK-like MADS-box genes in wild-type and peloric Phalaenopsis flowers. Front. Plant Sci. 5, 76. 10.3389/fpls.2014.00076 - DOI - PMC - PubMed
    1. Adamczyk B. J., Fernandez D. E. (2009). MIKC* MADS domain heterodimers are required for pollen maturation and tube growth in Arabidopsis. Plant Physiol. 149, 1713–1723. 10.1104/pp.109.135806 - DOI - PMC - PubMed
    1. Adamczyk B. J., Lehti-Shiu M. D., Fernandez D. E. (2007). The MADS domain factors AGL15 and AGL18 act redundantly as repressors of the floral transition in Arabidopsis. Plant J. 50, 1007–1019. 10.1111/j.1365-313X.2007.03105.x - DOI - PubMed
    1. Alvarez-Buylla E. R., Pelaz S., Liljegren S. J., Gold S. E., Burgeff C., Ditta G. S., et al. (2000). An ancestral MADS-box gene duplication occurred before the divergence of plants and animals. Proc. Natl. Acad. Sci. U. S. A. 97, 5328–5333. 10.1073/pnas.97.10.5328 - DOI - PMC - PubMed

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