Construction of a chloroplast DNA library from rye (Secale cereale), a cereal plant of temperature-inducible chloroplast ribosome deficiency.

The chloroplast genomes of flowering plants are circular DNA molecules, 120 to 160 kilobase pairs long, encoding the rRNA, all tRNAs, and 21 r-proteins of the chloroplast translational apparatus as well as key protein components of the photosynthetic and carbon reduction cycle reactions. In this paper we describe some characteristics of the rye chloroplast (plastid) genome and the construction and characterization of a clone library of 93% of its DNA in a plasmid and a cosmid vector. The size of rye chloroplast DNA is estimated at 135 kbp, similar to that for wheat and rice but slightly smaller than the estimate for maize (139 kbp). Chloroplast ribosome deficiency is induced in rye seedlings by germination and growth at 32 degrees-34 degrees C; therefore these clones would be useful for analyzing the regulation of chloroplast ribosome synthesis in higher plants, a process that requires coordinate expression of genes located in the nucleus and the chloroplast.