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, Lhcb1Pp1 encoding a light-harvesting chlorophyll a/b-b inding protein of photosystem II has been isolated from peach [Prunus persica (L,) Batsch, 'Stark Earliglo'] leaf genomic DNA, cloned, and s equenced. 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 annu al and other woody plants, respectively. In contrast, the amino acid s equence of the peach transit peptide is less conserved being 47 % to 6 9 % similar to those of annual plants and only 17% to 22% similar to t hose of other woody plants. The peach gene was used as a probe for Lhc b gene expression. Lhcb mRNA is detected in leaves of field-grown tree s during June to October. Lhcb mRNA is detected at a high level in lea ves 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 b e light-modulated in stems. Lhcb1Pp1contains four potential polyadeny lation sites, S1 nuclease analysis detected transcripts of the sizes e xpected from each of the four polyadenylation sites. All four are foun d in leaves of light-grown shoots and of field-grown trees throughout the growing season. In contrast, only three are detected in stems of l ight-grown shoots.