Limits...
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.

Show MeSH

Related in: MedlinePlus

Diurnal rhythm of phytosiderophore secretion (A) and HvYS1 expression (B) in barley. Root exudates were collected from Fe-deficient barley seedlings every 3 h in a glasshouse (sunrise 7:00 h) and roots were sampled at the same time point. The amount of phytosiderophore secreted was determined according to Ma et al. (2003). The expression level of HvYS1 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
getmorefigures.php?uid=PMC2724700&req=5

fig5: Diurnal rhythm of phytosiderophore secretion (A) and HvYS1 expression (B) in barley. Root exudates were collected from Fe-deficient barley seedlings every 3 h in a glasshouse (sunrise 7:00 h) and roots were sampled at the same time point. The amount of phytosiderophore secreted was determined according to Ma et al. (2003). The expression level of HvYS1 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: Secretion of phytosiderophore from the roots is characterized by a diurnal rhythm in some gramineous plants such as barley, wheat, and Festuca rubra (Takagi et al., 1984; Ma et al., 2003; Reichman and Parker, 2007). Generally, plants start to secrete phytosiderophores in the morning from the third hour after sunrise or the onset of the light period, and secretion continues for ∼3 h. However, gramineous plants such as maize do not show a diurnal rhythm in secretion (Yehuda et al., 1996). To investigate whether the expression of ZmYS1 and HvYS1 has a diurnal rhythm, the time-dependent expression of HvYS1 and ZmYS1 as well as phytosiderophore secretion were determined in Fe-deficient barley and maize. In Fe-deficient barley, the secretion of phytosiderophore showed a diurnal rhythm (P <0.01; Fig. 5A). With sunrise occurring at 7:00 h, the secretion reached a peak during 9:00–to 12:00 h. This result is in agreement with previous findings (Takagi et al., 1984). In contrast to the phytosiderophore secretion pattern, HvYS1 was expressed all day in the Fe-deficient barley roots (Fig. 5B). However, there was a significant fluctuation in the expression level (P <0.01). The peak of expression was found at 6:00 h, which was before sunrise (Fig. 5B), and remained at a constant level at 9:00 h, during the peak of phytosiderophore secretion. This result is not completely consistent with that of Nagasaka et al. (2009). They found that the expression peak of HvYS1 was at the start of illumination. Since they did not monitor the secretion of phytosiderophore at the same time, it is difficult to compare their results directly with the present results. Phytosiderophore is easily degraded by microorganisms (Watanabe and Wada, 1989); therefore, the expression of HvYS1 before the secretion of phytosiderophore will help the roots to take up the Fe(III)–phytosiderophore complex efficiently.


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 HvYS1 expression (B) in barley. Root exudates were collected from Fe-deficient barley seedlings every 3 h in a glasshouse (sunrise 7:00 h) and roots were sampled at the same time point. The amount of phytosiderophore secreted was determined according to Ma et al. (2003). The expression level of HvYS1 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

fig5: Diurnal rhythm of phytosiderophore secretion (A) and HvYS1 expression (B) in barley. Root exudates were collected from Fe-deficient barley seedlings every 3 h in a glasshouse (sunrise 7:00 h) and roots were sampled at the same time point. The amount of phytosiderophore secreted was determined according to Ma et al. (2003). The expression level of HvYS1 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: Secretion of phytosiderophore from the roots is characterized by a diurnal rhythm in some gramineous plants such as barley, wheat, and Festuca rubra (Takagi et al., 1984; Ma et al., 2003; Reichman and Parker, 2007). Generally, plants start to secrete phytosiderophores in the morning from the third hour after sunrise or the onset of the light period, and secretion continues for ∼3 h. However, gramineous plants such as maize do not show a diurnal rhythm in secretion (Yehuda et al., 1996). To investigate whether the expression of ZmYS1 and HvYS1 has a diurnal rhythm, the time-dependent expression of HvYS1 and ZmYS1 as well as phytosiderophore secretion were determined in Fe-deficient barley and maize. In Fe-deficient barley, the secretion of phytosiderophore showed a diurnal rhythm (P <0.01; Fig. 5A). With sunrise occurring at 7:00 h, the secretion reached a peak during 9:00–to 12:00 h. This result is in agreement with previous findings (Takagi et al., 1984). In contrast to the phytosiderophore secretion pattern, HvYS1 was expressed all day in the Fe-deficient barley roots (Fig. 5B). However, there was a significant fluctuation in the expression level (P <0.01). The peak of expression was found at 6:00 h, which was before sunrise (Fig. 5B), and remained at a constant level at 9:00 h, during the peak of phytosiderophore secretion. This result is not completely consistent with that of Nagasaka et al. (2009). They found that the expression peak of HvYS1 was at the start of illumination. Since they did not monitor the secretion of phytosiderophore at the same time, it is difficult to compare their results directly with the present results. Phytosiderophore is easily degraded by microorganisms (Watanabe and Wada, 1989); therefore, the expression of HvYS1 before the secretion of phytosiderophore will help the roots to take up the Fe(III)–phytosiderophore complex efficiently.

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