A vacuolar iron transporter in tulip, TgVit1, is responsible for blue coloration in petal cells through iron accumulation

Abstract

SUMMARYBlue color in flowers is due mainly to anthocyanins, and a considerable part of blue coloration can be attributed to metal-complexed anthocyanins. However, the mechanism of metal ion transport into vacuoles and subsequent flower color development has yet to be fully explored. Previously, we studied the mechanism of blue color development specifically at the bottom of the inner perianth in purple tulip petals of Tulipa gesneriana cv. Murasakizuisho. We found that differences in iron content were associated with the development of blue-and purple-colored cells. Here, we identify a vacuolar iron transporter in T. gesneriana (TgVit1), and characterize the localization and function of this transporter protein in tulip petals. The amino acid sequence of TgVit1 is 85% similar that of the Arabidopsis thaliana vacuolar iron transporter AtVIT1, and also showed similarity to the AtVIT1 homolog in yeast, Ca 2+ -sensitive cross-complementer 1 (CCC1). The gene TgVit1 was expressed exclusively in blue-colored epidermal cells, and protein levels increased with increasing mRNA expression and blue coloration. Transient expression experiments revealed that TgVit1 localizes to the vacuolar membrane, and is responsible for the development of the blue color in purple cells. Expression of TgVit1 in yeast rescued the growth defect of ccc1 mutant cells in the presence of high concentrations of FeSO 4 . Our results indicate that TgVit1 plays an essential role in blue coloration as a vacuolar iron transporter in tulip petals. These results suggest a new role for involvement of a vacuolar iron transporter in blue flower color development.

Bypassing Iron Storage in Endodermal Vacuoles Rescues the Iron Mobilization Defect in the natural resistance associated-macrophage protein3natural resistance associated-macrophage protein4 Double Mutant

“…S4). Previous studies have shown that the Dccc1 growth defect may be rescued by transformation with AtVIT1 and its homologs AtVTL1 (Gollhofer et al, 2014), LeVIT1 (Kim et al, 2006), TgVIT1 (Momonoi et al, 2009), and OsVIT1 or OsVIT2 (Zhang et al, 2012). Expression in yeast indicates that the G77D mutation prevents Dccc1 rescue by AtVIT1 but does not alter the AtVIT1 protein level or subcellular localization (Fig.…”

Identification of Two Novel Endoplasmic Reticulum Body-Specific Integral Membrane Proteins

“…MEB1 and MEB2 have DUF125 sequence. The proteins containing a DUF125 sequence are assigned as the VACUOLAR IRON TRANSPORTER (VIT) family, including CCC1 in yeast (Saccharomyces cerevisiae), AtVIT1 in Arabidopsis, TgVIT1 in tulip (Tulipa gesneriana), NODULIN21 in soybean (Glycine max), and LjSEN1 in Lotus japonicus (Delauney et al, 1990;Li et al, 2001;Kim et al, 2006;Momonoi et al, 2009;Hakoyama et al, 2012). The VIT family includes the iron/manganese uptake transporter.…”

The FRD3 Citrate Effluxer Promotes Iron Nutrition between Symplastically Disconnected Tissues throughout Arabidopsis Development

“…In plants, its availability is known to affect developmental programs such as root morphogenesis (Schmidt, 1999) and flower development and color (Takahashi et al, 2003;Momonoi et al, 2009). Iron entry in the biosphere is often limited by its solubility in the soil, despite its great abundance.…”