Cytological, Physiological, and Transcriptomic Analyses of the Leaf Color Mutant Yellow Leaf 20 (yl20) in Eggplant (Solanum melongena L.)

Abstract

Leaf color mutants are ideal materials for studying chlorophyll metabolism, chloroplast development, and photosynthesis in plants. We discovered a novel eggplant (Solanum melongena L.) mutant yl20 (yellow leaf 20) that exhibits yellow leaves. In this study, we compared the leaves of the mutant yl20 and wild type (WT) plants for cytological, physiological, and transcriptomic analyses. The results showed that the mutant yl20 exhibits abnormal chloroplast ultrastructure, reduced chlorophyll and carotenoid contents, and lower photosynthetic efficiency compared to the WT. Transcriptome data indicated 3267 and 478 differentially expressed genes (DEGs) between WT and yl20 lines in the cotyledon and euphylla stages, respectively, where most DEGs were downregulated in the yl20. Gene Ontology (GO) analysis revealed the “plastid-encoded plastid RNA polymerase complex” and the “chloroplast-related” terms were significantly enriched. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the significantly enriched DEGs were involved in flavone and flavonol biosynthesis, porphyrin and chlorophyll metabolism, etc. We speculated that these DEGs involved in significant terms were closely related to the leaf color development of the mutant yl20. Our results provide a possible explanation for the altered phenotype of leaf color mutants in eggplant and lay a theoretical foundation for plant breeding.