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Disruption of a gene for rice sucrose transporter, OsSUT1, impairs pollen function but pollen maturation is unaffected.

Hirose T, Zhang Z, Miyao A, Hirochika H, Ohsugi R, Terao T - J. Exp. Bot. (2010)

Bottom Line: Among the five SUT genes, OsSUT1 and OsSUT3 were found to be preferentially expressed and had temporal expression patterns that were distinct from each other.Expression of OsSUT1 in pollen was confirmed by a promoter-GUS fusion assay.However, starch accumulation during pollen development was not affected by disruption of OsSUT1, suggesting that the sugar(s) required for starch biosynthesis is supplied by other sugar transporters.

View Article: PubMed Central - PubMed

Affiliation: Hokuriku Research Center, National Agricultural Research Center, National Agriculture and Food Research Organization, Joetsu, Niigata 943-0193, Japan. dragon@affrc.go.jp

ABSTRACT
Sucrose transporters (SUTs) are known to play critical roles in the uptake of sucrose from the apoplast in various steps of sugar translocation. Because developing pollen is symplastically isolated from anther tissues, it is hypothesized that SUTs are active in the uptake of apoplastic sucrose into pollen. To investigate this possibility, a comprehensive expression analysis was performed for members of the SUT gene family in the developing pollen of rice (Oryza sativa L.) using real-time RT-PCR combined with a laser microdissection technique. Among the five SUT genes, OsSUT1 and OsSUT3 were found to be preferentially expressed and had temporal expression patterns that were distinct from each other. Expression of OsSUT1 in pollen was confirmed by a promoter-GUS fusion assay. The physiological function of OsSUT1 in pollen was further investigated using retrotransposon insertion mutant lines. While the homozygote of disrupted OsSUT1 (SUT1-/-) could not be obtained, heterozygote plants (SUT1+/-) showed normal grain filling. Their progeny segregated into SUT1+/- and SUT1+/+ with the ratio of 1:1, suggesting that the pollen disrupted for OsSUT1 is dysfunctional. This hypothesis was reinforced in vivo by a backcross of SUT1+/- plants with wild-type plants and also by in vitro pollen germination on the artificial media. However, starch accumulation during pollen development was not affected by disruption of OsSUT1, suggesting that the sugar(s) required for starch biosynthesis is supplied by other sugar transporters.

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Analysis of OsSUT1 expression in the glumaceous flowers of transgenic plants harbouring a OsSUT1 promoter::GUS construct. (A, D) Whole glumaceous flowers at stage I (A) and stage III (D). Bars indicate 1 mm. (B, C, E, F) Cross-sections of anthers of various developmental stages; (B) earlier than stage I (around 10 DTA), (C) stage I, (E) stage II, (F) stage IV. Bars indicate 0.1 mm. (B) and (C) are phase-contrast images to show the anatomy of the anthers better.
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fig2: Analysis of OsSUT1 expression in the glumaceous flowers of transgenic plants harbouring a OsSUT1 promoter::GUS construct. (A, D) Whole glumaceous flowers at stage I (A) and stage III (D). Bars indicate 1 mm. (B, C, E, F) Cross-sections of anthers of various developmental stages; (B) earlier than stage I (around 10 DTA), (C) stage I, (E) stage II, (F) stage IV. Bars indicate 0.1 mm. (B) and (C) are phase-contrast images to show the anatomy of the anthers better.

Mentions: The expression of OsSUT1 was then examined by histochemical staining using transgenic plants harbouring a OsSUT1 promoter::GUS construct. No staining was detected in the glumaceous flowers at stage I or earlier (Fig. 2A, B, C); clear staining was then observed in both the anther wall and pollen at stage II and later (Fig. 2D, E, F). These results are consistent with those from the RT-PCR analysis.


Disruption of a gene for rice sucrose transporter, OsSUT1, impairs pollen function but pollen maturation is unaffected.

Hirose T, Zhang Z, Miyao A, Hirochika H, Ohsugi R, Terao T - J. Exp. Bot. (2010)

Analysis of OsSUT1 expression in the glumaceous flowers of transgenic plants harbouring a OsSUT1 promoter::GUS construct. (A, D) Whole glumaceous flowers at stage I (A) and stage III (D). Bars indicate 1 mm. (B, C, E, F) Cross-sections of anthers of various developmental stages; (B) earlier than stage I (around 10 DTA), (C) stage I, (E) stage II, (F) stage IV. Bars indicate 0.1 mm. (B) and (C) are phase-contrast images to show the anatomy of the anthers better.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2921200&req=5

fig2: Analysis of OsSUT1 expression in the glumaceous flowers of transgenic plants harbouring a OsSUT1 promoter::GUS construct. (A, D) Whole glumaceous flowers at stage I (A) and stage III (D). Bars indicate 1 mm. (B, C, E, F) Cross-sections of anthers of various developmental stages; (B) earlier than stage I (around 10 DTA), (C) stage I, (E) stage II, (F) stage IV. Bars indicate 0.1 mm. (B) and (C) are phase-contrast images to show the anatomy of the anthers better.
Mentions: The expression of OsSUT1 was then examined by histochemical staining using transgenic plants harbouring a OsSUT1 promoter::GUS construct. No staining was detected in the glumaceous flowers at stage I or earlier (Fig. 2A, B, C); clear staining was then observed in both the anther wall and pollen at stage II and later (Fig. 2D, E, F). These results are consistent with those from the RT-PCR analysis.

Bottom Line: Among the five SUT genes, OsSUT1 and OsSUT3 were found to be preferentially expressed and had temporal expression patterns that were distinct from each other.Expression of OsSUT1 in pollen was confirmed by a promoter-GUS fusion assay.However, starch accumulation during pollen development was not affected by disruption of OsSUT1, suggesting that the sugar(s) required for starch biosynthesis is supplied by other sugar transporters.

View Article: PubMed Central - PubMed

Affiliation: Hokuriku Research Center, National Agricultural Research Center, National Agriculture and Food Research Organization, Joetsu, Niigata 943-0193, Japan. dragon@affrc.go.jp

ABSTRACT
Sucrose transporters (SUTs) are known to play critical roles in the uptake of sucrose from the apoplast in various steps of sugar translocation. Because developing pollen is symplastically isolated from anther tissues, it is hypothesized that SUTs are active in the uptake of apoplastic sucrose into pollen. To investigate this possibility, a comprehensive expression analysis was performed for members of the SUT gene family in the developing pollen of rice (Oryza sativa L.) using real-time RT-PCR combined with a laser microdissection technique. Among the five SUT genes, OsSUT1 and OsSUT3 were found to be preferentially expressed and had temporal expression patterns that were distinct from each other. Expression of OsSUT1 in pollen was confirmed by a promoter-GUS fusion assay. The physiological function of OsSUT1 in pollen was further investigated using retrotransposon insertion mutant lines. While the homozygote of disrupted OsSUT1 (SUT1-/-) could not be obtained, heterozygote plants (SUT1+/-) showed normal grain filling. Their progeny segregated into SUT1+/- and SUT1+/+ with the ratio of 1:1, suggesting that the pollen disrupted for OsSUT1 is dysfunctional. This hypothesis was reinforced in vivo by a backcross of SUT1+/- plants with wild-type plants and also by in vitro pollen germination on the artificial media. However, starch accumulation during pollen development was not affected by disruption of OsSUT1, suggesting that the sugar(s) required for starch biosynthesis is supplied by other sugar transporters.

Show MeSH