Isolation and characterization of a type I gene encoding a light-harvesting chlorophyll a/b-binding protein of photosystem II in peach

A nuclear gene, Lhcb1*Pp1, encoding a light-harvesting chlorophyll a/b-binding protein of photosystem II has been isolated from peach [Prunus persica (L.) Batsch. 'Stark Earliglo'] leaf genomic DNA, cloned, and sequenced. This gene encodes a precursor polypeptide of 267 amino acids with a transit peptide of 34 and a type I mature protein of 233 amino acids. The amino acid sequence of the mature polypeptide is 89% to 94 % and 80% to 94% similar to those encoded by type I Lhcb genes of annual and other woody plants, respectively. In contrast, the amino acid sequence of the peach transit peptide is less conserved being 47% to 69% similar to those of annual plants and only 17 % to 22% similar to those of other woody plants. The peach gene was used as a probe for Lhcb gene expression. Lhcb mRNA is detected in leaves of field-grown trees during June to October. Lhcb mRNA is detected at a high level in leaves of peach shoots grown in tissue culture in the light, but only at a trace level in leaves grown in the dark. Some Lhcb genes appear to be light-modulated in stems. Lhcb1*Pp1 contains four potential polyadenylation sites. S1 nuclease analysis detected transcripts of the sizes expected from each of the four polyadenylation sites. All four are found in leaves of light-grown shoots and of field-grown trees throughout the growing season. In contrast, only three are detected in stems of light-grown shoots.