A petal‐specific InMYB1 promoter from Japanese morning glory: a useful tool for molecular breeding of floricultural crops

Abstract

These two authors contributed equally to this work. Keywords: floricultural crops,Ipomoea nil, molecular breeding, MYB, petal-specific promoter. SummaryProduction of novel transgenic floricultural crops with altered petal properties requires transgenes that confer a useful trait and petal-specific promoters. Several promoters have been shown to control transgenes in petals. However, all suffer from inherent drawbacks such as low petal specificity and restricted activity during the flowering stage. In addition, the promoters were not examined for their ability to confer petal-specific expression in a wide range of plant species. Here, we report the promoter of InMYB1 from Japanese morning glory as a novel petalspecific promoter for molecular breeding of floricultural crops. First, we produced stable InMYB1_1kb::GUS transgenic Arabidopsis and Eustoma plants and characterized spatial and temporal expression patterns under the control of the InMYB1 promoter by histochemical b-glucuronidase (GUS) staining. GUS staining patterns were observed only in petals. This result showed that the InMYB1 promoter functions as a petal-specific promoter. Second, we transiently introduced the InMYB1_1 kb::GUS construct into Eustoma, chrysanthemum, carnation, Japanese gentian, stock, rose, dendrobium and lily petals by particle bombardment. GUS staining spots were observed in Eustoma, chrysanthemum, carnation, Japanese gentian and stock. These results showed that the InMYB1 promoter functions in most dicots. Third, to show the InMYB1 promoter utility in molecular breeding, a MIXTA-like gene function was suppressed or enhanced under the control of InMYB1 promoter in Arabidopsis. The transgenic plant showed a conspicuous morphological change only in the form of wrinkled petals. Based on these results, the InMYB1 promoter can be used as a petal-specific promoter in molecular breeding of floricultural crops.

Enhanced cuticle accumulation by employing MIXTA-like transcription factors

“…These results suggest that the CYP86A4 promoter induces increase of cuticle nanoridges and alters the resultant petal texture more effectively than the CYP77A6 promoter in floral organs, and that MIXTAlike TFs consistently induce nanoridge production in nanoridge-forming cells. Our observations regarding the petal adaxial surface are consistent with those of plants expressing MYB106-VP16 under the control of the petalspecific InMYB1_1kb promoter (Azuma et al 2016).…”

GB3.0: a platform for plant bio-design that connects functional DNA elements with associated biological data

“…Ectopic expression often results from overexpression of the TFs using constitutive promoters or, in a few examples, is made dependent of endogenously regulated factors as, e.g. ripening (47), senescence (49) or tissue specific factors (50–52). A step forward in transcriptional control would involve connecting endogenous pathways (e.g.…”

Dissecting promoter of <i>InMYB1</i> gene showing petal-specific expression

“…Elongation factor-1α (AtEF1) was used as an internal control. Total RNA was isolated from stage-3 flower buds (Azuma et al 2016b) using Trizol (Thermo Fisher Scientific, MA, USA) and reverse-transcribed using PrimeScript RT reagent Kit with gDNA Eraser (TaKaRa, Shiga, Japan). Real-time PCR was carried out using obtained cDNA and SYBR Premix EX Taq (TaKaRa, Shiga, Japan) with StepOnePlus real-time PCR system (Thermo Fisher Scientific, MA, USA).…”

“…In the InMYB1_403b::GUS or InMYB1_332b::GUS transgenic plants, it was decreased to 50% or 30%, respectively, and no GUS staining was observed in the InMYB1_200b::GUS and InMYB1_140b::GUS transgenic plants (Figure 3). We previously reported that some kinds of cis-element such as CAAT-box, which increases promoter activity, exist in the 1023-332 bp upstream region of InMYB1 (Azuma et al 2016b). Although the petal-specific promoter activity became weaker and unstable by deletion of the several cis-elements, the 332 bp upstream region of InMYB1 still functioned as a petalspecific promoter.…”