WLP3 Encodes the Ribosomal Protein L18 and Regulates Chloroplast Development in Rice

Abstract

Abstract Plastid ribosomal proteins play a crucial role in the growth and development of plants, predominantly in key gene translation and expression within chloroplasts. While some information is known about the regulatory processes of plastid ribosomal proteins in many plant species, there is limited knowledge about the underlying mechanisms in rice. In this study, ethyl methanesulfonate (EMS) mutagenesis was used to induce a new mutant called wlp3 (white leaf and panicle3), characterized by white or albino leaves and panicle, exhibiting this phenotype from the second-leaf stage until tillering. Furthermore, the newly emerging leaves developed the same phenotype as the ZH11 rice variety after a certain period, while the albino leaves of wlp3 displayed incomplete chloroplast structure and significantly low chlorophyll content. A transition mutation (T to C) at position 380 was identified in the coding region of the LOC_Os03g61260 gene, resulting in the substitution of isoleucine with threonine during translation. WLP3 encodes the ribosomal L18 subunit, which is localized in the chloroplast. Complementation experiments confirmed that LOC_Os03g61260 was responsible for the albino phenotype in rice. During the seedling stage, wlp3 expression was higher in leaves and panicles. Compared to the wild-type (WT), wlp3 exhibited reduced chlorophyll synthesis and significantly decreased expression levels of genes associated with plastid development. Yeast two-hybrid (Y2H) analysis demonstrated that WLP3 interacts with other ribosomal subunits, thereby influencing chloroplast development. These findings contribute to a further understanding of the underlying molecular mechanisms of chloroplast development and plastid gene translation.