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Further characterization of ferric-phytosiderophore transporters ZmYS1 and HvYS1 in maize and barley.

Ueno D, Yamaji N, Ma JF - J. Exp. Bot. (2009)

Bottom Line: Here, this transporter in maize (ZmYS1) and barley (HvYS1) was further characterized and compared in terms of expression pattern, diurnal change, and tissue-type specificity of localization.In contrast, ZmYS1 did not show such a rhythm in expression.These differences in gene expression pattern and tissue-type specificity of localization suggest that HvYS1 is only involved in primary Fe acquisition by barley roots, whereas ZmYS1 is involved in both primary Fe acquisition and intracellular transport of iron and other metals in maize.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Bioresources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.

ABSTRACT
Roots of some gramineous plants secrete phytosiderophores in response to iron deficiency and take up Fe as a ferric-phytosiderophore complex through the transporter YS1 (Yellow Stripe 1). Here, this transporter in maize (ZmYS1) and barley (HvYS1) was further characterized and compared in terms of expression pattern, diurnal change, and tissue-type specificity of localization. The expression of HvYS1 was specifically induced by Fe deficiency only in barley roots, and increased with the progress of Fe deficiency, whereas ZmYS1 was expressed in maize in the leaf blades and sheaths, crown, and seminal roots, but not in the hypocotyl. HvYS1 expression was not induced by any other metal deficiency. Furthermore, in maize leaf blades, the expression was higher in the young leaf blades showing severe chlorosis than in the old leaf blades showing no chlorosis. The expression of HvYS1 showed a distinct diurnal rhythm, reaching a maximum before the onset of phytosiderophore secretion. In contrast, ZmYS1 did not show such a rhythm in expression. Immunostaining showed that ZmYS1 was localized in the epidermal cells of both crown and lateral roots, with a polar localization at the distal side of the epidermal cells. In maize leaves, ZmYS1 was localized in mesophyll cells, but not epidermal cells. These differences in gene expression pattern and tissue-type specificity of localization suggest that HvYS1 is only involved in primary Fe acquisition by barley roots, whereas ZmYS1 is involved in both primary Fe acquisition and intracellular transport of iron and other metals in maize.

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Tissue-specific localization of ZmYS1 in maize roots. (A, D) Immunostaining with anti-ZmYS1 antibody in the crown (A) and lateral roots (D) of maize grown in a nutrient solution containing Fe. (B, C, E, and F), Immunostaining in the crown (B and C) and lateral roots (E and F) of maize grown in Fe-free nutrient solution. Scale bars indicate 100 μm.
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fig7: Tissue-specific localization of ZmYS1 in maize roots. (A, D) Immunostaining with anti-ZmYS1 antibody in the crown (A) and lateral roots (D) of maize grown in a nutrient solution containing Fe. (B, C, E, and F), Immunostaining in the crown (B and C) and lateral roots (E and F) of maize grown in Fe-free nutrient solution. Scale bars indicate 100 μm.

Mentions: Immunostaining showed that HvYS1 is localized to the epidermal cells in the Fe-deficient barley roots (Murata et al., 2006). However, in maize, the tissue-type specificity of localization of ZmYS1 is unknown. The localization was investigated by immunostaining with anti-ZmYS1 polyclonal antibody. In the Fe-sufficient maize, the signal of ZmYS1 was hardly observed in both the crown and lateral roots (Fig. 7A, D). However, in the Fe-deficient maize, ZmYS1 was found to be localized at the epidermal cells of crown and lateral roots (Fig. 7B. E). This localization is similar to HvYS1 (Murata et al., 2006). However, different from HvYS1, ZmYS1 showed polar localization at the distal side of the epidermal cells. Polar localization of some mineral transporters has been reported recently. For example, an influx silicon transporter Lsi1 is localized at the distal side of the exodermal and endodermal cells of rice roots (Ma et al., 2006), while an efflux silicon transporter Lsi2 is localized at the proximal side of the same cells (Ma et al., 2007). In maize roots, the Si influx transporter ZmLsi1 also showed polar localization at the distal side of epidermal and cortical cells (Mitani et al., 2009). To our knowledge, this is the first time that polar localization has been described for a metal complex transporter. The mechanism controlling polar localization of transporters has not been described. It will be interesting to elucidate the mechanism of polar localization by comparing HvYS1 and ZmYS1 in the future.


Further characterization of ferric-phytosiderophore transporters ZmYS1 and HvYS1 in maize and barley.

Ueno D, Yamaji N, Ma JF - J. Exp. Bot. (2009)

Tissue-specific localization of ZmYS1 in maize roots. (A, D) Immunostaining with anti-ZmYS1 antibody in the crown (A) and lateral roots (D) of maize grown in a nutrient solution containing Fe. (B, C, E, and F), Immunostaining in the crown (B and C) and lateral roots (E and F) of maize grown in Fe-free nutrient solution. Scale bars indicate 100 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724700&req=5

fig7: Tissue-specific localization of ZmYS1 in maize roots. (A, D) Immunostaining with anti-ZmYS1 antibody in the crown (A) and lateral roots (D) of maize grown in a nutrient solution containing Fe. (B, C, E, and F), Immunostaining in the crown (B and C) and lateral roots (E and F) of maize grown in Fe-free nutrient solution. Scale bars indicate 100 μm.
Mentions: Immunostaining showed that HvYS1 is localized to the epidermal cells in the Fe-deficient barley roots (Murata et al., 2006). However, in maize, the tissue-type specificity of localization of ZmYS1 is unknown. The localization was investigated by immunostaining with anti-ZmYS1 polyclonal antibody. In the Fe-sufficient maize, the signal of ZmYS1 was hardly observed in both the crown and lateral roots (Fig. 7A, D). However, in the Fe-deficient maize, ZmYS1 was found to be localized at the epidermal cells of crown and lateral roots (Fig. 7B. E). This localization is similar to HvYS1 (Murata et al., 2006). However, different from HvYS1, ZmYS1 showed polar localization at the distal side of the epidermal cells. Polar localization of some mineral transporters has been reported recently. For example, an influx silicon transporter Lsi1 is localized at the distal side of the exodermal and endodermal cells of rice roots (Ma et al., 2006), while an efflux silicon transporter Lsi2 is localized at the proximal side of the same cells (Ma et al., 2007). In maize roots, the Si influx transporter ZmLsi1 also showed polar localization at the distal side of epidermal and cortical cells (Mitani et al., 2009). To our knowledge, this is the first time that polar localization has been described for a metal complex transporter. The mechanism controlling polar localization of transporters has not been described. It will be interesting to elucidate the mechanism of polar localization by comparing HvYS1 and ZmYS1 in the future.

Bottom Line: Here, this transporter in maize (ZmYS1) and barley (HvYS1) was further characterized and compared in terms of expression pattern, diurnal change, and tissue-type specificity of localization.In contrast, ZmYS1 did not show such a rhythm in expression.These differences in gene expression pattern and tissue-type specificity of localization suggest that HvYS1 is only involved in primary Fe acquisition by barley roots, whereas ZmYS1 is involved in both primary Fe acquisition and intracellular transport of iron and other metals in maize.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Bioresources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.

ABSTRACT
Roots of some gramineous plants secrete phytosiderophores in response to iron deficiency and take up Fe as a ferric-phytosiderophore complex through the transporter YS1 (Yellow Stripe 1). Here, this transporter in maize (ZmYS1) and barley (HvYS1) was further characterized and compared in terms of expression pattern, diurnal change, and tissue-type specificity of localization. The expression of HvYS1 was specifically induced by Fe deficiency only in barley roots, and increased with the progress of Fe deficiency, whereas ZmYS1 was expressed in maize in the leaf blades and sheaths, crown, and seminal roots, but not in the hypocotyl. HvYS1 expression was not induced by any other metal deficiency. Furthermore, in maize leaf blades, the expression was higher in the young leaf blades showing severe chlorosis than in the old leaf blades showing no chlorosis. The expression of HvYS1 showed a distinct diurnal rhythm, reaching a maximum before the onset of phytosiderophore secretion. In contrast, ZmYS1 did not show such a rhythm in expression. Immunostaining showed that ZmYS1 was localized in the epidermal cells of both crown and lateral roots, with a polar localization at the distal side of the epidermal cells. In maize leaves, ZmYS1 was localized in mesophyll cells, but not epidermal cells. These differences in gene expression pattern and tissue-type specificity of localization suggest that HvYS1 is only involved in primary Fe acquisition by barley roots, whereas ZmYS1 is involved in both primary Fe acquisition and intracellular transport of iron and other metals in maize.

Show MeSH
Related in: MedlinePlus