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Investigations on the photoregulation of chloroplast movement and leaf positioning in Arabidopsis.

Han IS, Cho HY, Moni A, Lee AY, Briggs WR - Plant Cell Physiol. (2012)

Bottom Line: The effect is far-red reversible.This photoreversible response is normal in a phyB mutant but does not appear in a phyA mutant.These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea. hanis@ulsan.ac.kr

ABSTRACT
We recently investigated the roles of the phototropin 1 (PHOT1) LOV (light, oxygen or voltage) domains in mediating phototropic curvature in transgenic Arabidopsis seedlings expressing either wild-type PHOT1 or PHOT1 with one or both LOV domains inactivated by a single amino acid replacement. We have now investigated the role of the PHOT1 LOV domains in chloroplast movement and in leaf positioning in response to blue light. Low fluence rate blue light is known to mediate a chloroplast accumulation response and high fluence rate blue light an avoidance response in Arabidopsis leaves. As was the case for phototropism, LOV2 of PHOT1 is essential for chloroplast accumulation and LOV1 is dispensable. PHOT1 LOV2 is also essential to maintain developing primary leaves in a horizontal position under white light from above and LOV1 is again dispensable. A red light pulse given to dark-adapted light-grown plants followed by 2 h of darkness enhances both the chloroplast accumulation response under dim blue light and the chloroplast avoidance response under strong blue light. The effect is far-red reversible. This photoreversible response is normal in a phyB mutant but does not appear in a phyA mutant. These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.

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Leaf shapes of the transformed plants with the PHOT2 LOV1 LOV2 construct. Only line 5-c complements the leaf-flattening response.
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pcs098-F4: Leaf shapes of the transformed plants with the PHOT2 LOV1 LOV2 construct. Only line 5-c complements the leaf-flattening response.

Mentions: Note that line 5-c (both LOV domains intact) also complemented the leaf flattening response (Fig. 4, Table 1), whereas lines 5-a and 5-d both failed to do so. Cho et al. (2007) did obtain partial complementation of flattening with line 5-d, possibly because their plants were slightly younger than ours. In addition, in their hands, line 5-d showed complete complementation for PHOT2-mediated phototropism of etiolated hypocotyls. Thus the level of PHOT2 protein expression in the etiolated hypocotyl of line 5-d is sufficient for phototropism whereas the level in the leaves is insufficient for complete leaf flattening.Table 1


Investigations on the photoregulation of chloroplast movement and leaf positioning in Arabidopsis.

Han IS, Cho HY, Moni A, Lee AY, Briggs WR - Plant Cell Physiol. (2012)

Leaf shapes of the transformed plants with the PHOT2 LOV1 LOV2 construct. Only line 5-c complements the leaf-flattening response.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539441&req=5

pcs098-F4: Leaf shapes of the transformed plants with the PHOT2 LOV1 LOV2 construct. Only line 5-c complements the leaf-flattening response.
Mentions: Note that line 5-c (both LOV domains intact) also complemented the leaf flattening response (Fig. 4, Table 1), whereas lines 5-a and 5-d both failed to do so. Cho et al. (2007) did obtain partial complementation of flattening with line 5-d, possibly because their plants were slightly younger than ours. In addition, in their hands, line 5-d showed complete complementation for PHOT2-mediated phototropism of etiolated hypocotyls. Thus the level of PHOT2 protein expression in the etiolated hypocotyl of line 5-d is sufficient for phototropism whereas the level in the leaves is insufficient for complete leaf flattening.Table 1

Bottom Line: The effect is far-red reversible.This photoreversible response is normal in a phyB mutant but does not appear in a phyA mutant.These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Ulsan, Ulsan 680-749, Korea. hanis@ulsan.ac.kr

ABSTRACT
We recently investigated the roles of the phototropin 1 (PHOT1) LOV (light, oxygen or voltage) domains in mediating phototropic curvature in transgenic Arabidopsis seedlings expressing either wild-type PHOT1 or PHOT1 with one or both LOV domains inactivated by a single amino acid replacement. We have now investigated the role of the PHOT1 LOV domains in chloroplast movement and in leaf positioning in response to blue light. Low fluence rate blue light is known to mediate a chloroplast accumulation response and high fluence rate blue light an avoidance response in Arabidopsis leaves. As was the case for phototropism, LOV2 of PHOT1 is essential for chloroplast accumulation and LOV1 is dispensable. PHOT1 LOV2 is also essential to maintain developing primary leaves in a horizontal position under white light from above and LOV1 is again dispensable. A red light pulse given to dark-adapted light-grown plants followed by 2 h of darkness enhances both the chloroplast accumulation response under dim blue light and the chloroplast avoidance response under strong blue light. The effect is far-red reversible. This photoreversible response is normal in a phyB mutant but does not appear in a phyA mutant. These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.

Show MeSH
Related in: MedlinePlus