The rice nuclear gene WLP1 encoding a chloroplast ribosome L13 protein is needed for chloroplast development in rice grown under low temperature conditions.

Plastidial ribosome proteins (PRPs) form the major component of the plastidial ribosome. Here we describe a rice mutant named wlp1 (white leaf and panicles 1) selected from a population of tissue culture regenerants. The early seedling leaves of the mutant were albino, as was the immature panicle at heading, and the phenotype was more strongly expressed in plants exposed to low temperature conditions. Changes in the leaf pigmentation of the mutant were due to altered chlorophyll content and chloroplast development. Positional cloning of WLP1, followed by complementation and knock-down experiments, showed that it encodes a 50S ribosome L13 protein. The WLP1 protein localized to the chloroplast. WLP1 was mainly transcribed in green tissues and particularly abundantly in the early seedling leaves. In addition, the expression level of WLP1 was induced by the low temperature. The transcription pattern of a number of genes involved in plastidial transcription/translation and in photosynthesis was altered in the wlp1 mutants. These results reveal that WLP1 is required for normal chloroplast development, especially under low temperature conditions. This is the first report on the function of PRPs in rice.