Differential expression in Arabidopsis of Lhca2, a PSI cab gene.

A cDNA clone of the gene Lhca2 encoding a photosystem I (PSI) type II chlorophyll a/b-binding protein was isolated from Arabidopsis thaliana. The isolation of this, the fourth PSI cab gene from Arabidopsis, confirms a previous report [1] that indicated Arabidopsis may contain all four PSI cab genes identified in other plant species. Lhca2 is a single-copy gene as are the other known Arabidopsis PSI cab genes. The patterns of developmental expression and tissue-specific regulation of Lhca2 are similar to those of other PSI and PSII cab genes, but the light induction pattern and the steady-state mRNA level of Lhca2 are distinct. This suggests that a different mechanism may be employed to regulate the expression of Lhca2.