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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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Diurnal rhythm of phytosiderophore secretion (A) and ZmYS1 expression (B) in maize. Root exudates were collected from Fe-deficient maize seedlings every 3 h (sunrise 5:00 h) and roots and shoots were sampled at the same time point. The amount of phytosiderophore secreted was determined by HPLC according to Ueno et al. (2007). The expression level of ZmYS1 at different times was determined by quantitative RT-PCR. The relative mRNA levels in the roots at 6:00 h are shown. Data are means ±SD (n=3).
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fig6: Diurnal rhythm of phytosiderophore secretion (A) and ZmYS1 expression (B) in maize. Root exudates were collected from Fe-deficient maize seedlings every 3 h (sunrise 5:00 h) and roots and shoots were sampled at the same time point. The amount of phytosiderophore secreted was determined by HPLC according to Ueno et al. (2007). The expression level of ZmYS1 at different times was determined by quantitative RT-PCR. The relative mRNA levels in the roots at 6:00 h are shown. Data are means ±SD (n=3).

Mentions: In contrast, the secretion of phytosiderophore in the Fe-deficient maize roots did not show a distinct diurnal rhythm as seen in barley (P >0.05; Fig. 6A). This is in agreement with previous findings (Yehuda et al., 1996). Interestingly, there was also no diurnal change in the expression of ZmYS1 in either the roots or shoots (P >0.05; Fig. 6B). Although the mechanism controlling the diurnal rhythm of phytosiderophore secretion and YS1 expression is still unknown, it would be interesting to compare the promoter regions of 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)

Diurnal rhythm of phytosiderophore secretion (A) and ZmYS1 expression (B) in maize. Root exudates were collected from Fe-deficient maize seedlings every 3 h (sunrise 5:00 h) and roots and shoots were sampled at the same time point. The amount of phytosiderophore secreted was determined by HPLC according to Ueno et al. (2007). The expression level of ZmYS1 at different times was determined by quantitative RT-PCR. The relative mRNA levels in the roots at 6:00 h are shown. Data are means ±SD (n=3).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig6: Diurnal rhythm of phytosiderophore secretion (A) and ZmYS1 expression (B) in maize. Root exudates were collected from Fe-deficient maize seedlings every 3 h (sunrise 5:00 h) and roots and shoots were sampled at the same time point. The amount of phytosiderophore secreted was determined by HPLC according to Ueno et al. (2007). The expression level of ZmYS1 at different times was determined by quantitative RT-PCR. The relative mRNA levels in the roots at 6:00 h are shown. Data are means ±SD (n=3).
Mentions: In contrast, the secretion of phytosiderophore in the Fe-deficient maize roots did not show a distinct diurnal rhythm as seen in barley (P >0.05; Fig. 6A). This is in agreement with previous findings (Yehuda et al., 1996). Interestingly, there was also no diurnal change in the expression of ZmYS1 in either the roots or shoots (P >0.05; Fig. 6B). Although the mechanism controlling the diurnal rhythm of phytosiderophore secretion and YS1 expression is still unknown, it would be interesting to compare the promoter regions of 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