Abstract
Leaf color mutants in higher plants are ideal materials for investigating the structure and function of photosynthetic system. In this study, we identified a cucumber vyl (virescent-yellow leaf) mutant in the mutant library, which exhibited reduced pigment contents and delayed chloroplast development process. F2 and BC1 populations were constructed from the cross between vyl mutant and cucumber inbred line ‘Hazerd’ to identify that the vyl trait is controlled by a simply recessive gene designated as CsVYL. The CsVYL gene was mapped to a 3.8 cM interval on chromosome 4 using these 80 F2 individuals and BSA (bulked segregation analysis) approach. Fine genetic map was conducted with 1542 F2 plants and narrowed down the vyl locus to an 86.3 kb genomic region, which contains a total of 11 genes. Sequence alignment between the wild type (WT) and vyl only identified one single nucleotide mutation (C→T) in the first exon of gene Csa4G637110, which encodes a DnaJ-like zinc finger protein. Gene Expression analysis confirmed the differences in transcription level of Csa4G637110 between wild type and mutant plants. Map-based cloning of the CsVYL gene could accelerate the study of chloroplast development and chlorophyll synthesis of cucumber.
Highlights
Leaf is a vital organ for plant photosynthesis that occurs mainly in chloroplasts
The virescent yellow-leaf mutant was isolated from an M2 family derived from an ethyl methanesulfonate (EMS)-mutagenized cucumber ‘Changchunmici’ (CCMC, wild type, WT, a common inbred line with green leaf) population
Different from leaf color mutant reported previously (Miao et al, 2016), the mutant studied in this work exhibited virescent yellow leaf only in true leaves whereas the leaf vein remains green (Figure 1B)
Summary
Leaf is a vital organ for plant photosynthesis that occurs mainly in chloroplasts. Chloroplast, a semiautonomous organelle exits only in plant cells, can synthesize various metabolites that are essential for plant growth and development, and maintenance of green leaf color (Moreira et al, 2000). Leaf color mutants are formed due to silencing or inactivation of genes controlling chlorophyll biosynthesis and chloroplast development, which directly or indirectly affects chlorophyll synthesis and degradation, leading to leaf color variation (Motohashi et al, 2003). Leaf color mutants are the ideal materials to study the mechanism of plant photosynthesis, chloroplast ultrastructure, chlorophyll biosynthetic pathway, expression and regulation of related genes (Stern et al, 2004). Numerous studies have been reported in relative genetic, physiological and molecular mechanism research
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