Phytochrome Modulation of Blue Light-Induced Chloroplast Movements in Arabidopsis1

AUTOR(ES)

DeBlasio, Stacy L.

FONTE

The American Society for Plant Biologists

RESUMO

Photometric analysis of chloroplast movements in various phytochrome (phy) mutants of Arabidopsis showed that phyA, B, and D are not required for chloroplast movements because blue light (BL)-dependent chloroplast migration still occurs in these mutants. However, mutants lacking phyA or phyB showed an enhanced response at fluence rates of BL above 10 μmol m-2 s-1. Overexpression of phyA or phyB resulted in an enhancement of the low-light response. Analysis of chloroplast movements within the range of BL intensities in which the transition between the low- and high-light responses occur (1.5-15 μmol m-2 s-1) revealed a transient increase in light transmittance through leaves, indicative of the high-light response, followed by a decrease in transmittance to a value below that measured before the BL treatment, indicative of the low-light response. A biphasic response was not observed for phyABD leaves exposed to the same fluence rate of BL, suggesting that phys play a role in modulating the transition between the low- and high-light chloroplast movement responses of Arabidopsis.

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