Plant biology

Lighting up Photosynthesis

Science's STKE  23 Jan 2001:
Vol. 2001, Issue 66, pp. tw1
DOI: 10.1126/stke.2001.66.tw1

Plants detect light of specific wavelengths with specific photoreceptors called phytochromes. One light-activated developmental pathway is the transition from nonphotosynthetically active protoplasts to photosynthetically active chloroplasts. Møller et al. isolated the laf6 mutant in Arabidopsis, which was defective in responding to far-red light (the phytochrome A pathway). Laf6 encodes a protein (atABC1) with similarity to the small soluble ATP-binding cassette transporters and with a functional chloroplast localization signal in the NH2-terminus. These small ABC transporters typically are associated functionally with a second subunit that spans the membrane and are usually involved in import. Consistent with a role in import, laf6 seedlings have decreased chlorophyll content and increased cytosolic chlorophyll precursors. The laf6 phenotype can be reproduced by chemical inhibition of the enzyme responsible for the conversion of the chlorophyll precursor protoporphyrinogen IX and increased levels of atABC1 can prevent this phenotype, further supporting a role for atABC1 in chlorophyll precursor import. Thus, atABC1 is one of the downstream targets of light-activated phytochrome A and provides a link between light-sensing and photosynthesis.

S. G. Møller, T. Kunkel, N.-H. Chua, A plastidic ABC protein involved in intercompartmental communication of light signaling. Genes Dev. 15, 90-103 (2001). [Abstract] [Full Text]