Insights into the molecular basis of a yellow leaf color mutant (ym) in tomato (Solanum lycopersicum)

Abstract

Leaf color mutants are ideal materials for studying mechanisms of plant such as photosynthesis, photorespiration, the pigment biosynthesis, and some other agronomic traits. Meanwhile, leaf color mutants are widely used in the screening of the offspring of cross breeding. The molecular mechanisms of yellow leaf and REDOX balance of tomatoes have not been explored. Here we obtain a naturally yellow leaf tomato mutant (ym). In order to further understand the role of REDOX, a series of experiments are conducted to assess the physiological and molecular reactions of two tomato lines, ym and zs4. The results showed that the ym mutant cells accumulated excessive H2O2. The chlorophyll content of the mutant decreased greatly. The chloroplast structure of the mutant is observed by transmission electron microscope (TEM). The results showed that mutant's chloroplast membrane structure is seriously damaged. A transcriptomic approach is used to analyze the gene regulate etiolation traits in ym mutant tomato plants. Many genes are enriched in oxidation-reduction (REDOX). Kyoto encyclopedia of genes and genomes (KEGG) revealed that DEGs are involved in pathways such as plant hormone signal transduction, carotenoid biosynthesis, MAPK signaling pathway, phenols and flavonoids synthesis, and pentose and glucuronate interconversions, which further confirmed the role of yellow trait. Overall, the damage of chloroplast structure, low pigment content and low level ROS scavenging capability are the main factors leading to yellow leaf.Main ConclusionDamage of chloroplast structure lead to the low level of the chlorophyll and the REDOX imbalance cause tomato yellow leaf color.