LAUSR

Potassium efflux antiporters (KEAs) play important roles in the regulation of monovalent cation efflux to maintain ion homeostasis in plant cells; however, details of their function in chloroplast development remain elusive, especially under stress conditions. Here, we identified a KEA family gene based on three chlorophyll-deficient mutants, cde3-1, 2, 3. These cde3 mutants exhibit serious white stripe leaf and an albino midrib phenotype, reduced level of photosynthetic pigments, and arrested chloroplast development under high-temperature conditions. Map-based cloning and allelism tests showed that CDE3 encodes a putative KEA protein in rice. CDE3 is mainly expressed in green tissues, with maximum transcript abundance in young leaves. Subcellular localization analysis showed that CDE3 is localized in chloroplasts. Quantitative real-time PCR analysis showed that expression levels of genes associated with chlorophyll biosynthesis, photosynthesis, and chloroplast development are affected in cde3-1, which suggest that CDE3 plays an important role in chloroplast K+/H+ homeostasis and chloroplast development under high-temperature conditions.