Abstract
The leaf is an important photosynthetic organ and plays an essential role in the growth and development of plants. Leaf color mutants are ideal materials for studying chlorophyll metabolism, chloroplast development, and photosynthesis. In this study, we identified an EMS-induced mutant, yl2.1, which exhibited yellow cotyledons and true leaves that did not turn green with leaf growth. The yl2.1 locus was controlled by a recessive nuclear gene. The CsYL2.1 was mapped to a 166.7-kb genomic region on chromosome 2, which contains 24 predicted genes. Only one non-synonymous single nucleotide polymorphism (SNP) was found between yl2.1 and wt-WD1 that was located in Exon 7 of Csa2G263900, resulting in an amino acid substitution. CsYL2.1 encodes a plastid isoform of triose phosphate isomerase (pdTPI), which catalyzes the reversible conversion of dihydroxyacetone phosphate (DHAP) to glyceraldehyde-3-phosphate (GAP) in chloroplasts. CsYL2.1 was highly expressed in the cotyledons and leaves. The mesophyll cells of the yl2.1 leaves contained reduced chlorophyll and abnormal chloroplasts. Correspondingly, the photosynthetic efficiency of the yl2.1 leaves was impaired. Identification of CsYL2.1 is helpful in elucidating the function of ptTPI in the chlorophyll metabolism and chloroplast development and understanding the molecular mechanism of this leaf color variant in cucumber.
Highlights
Chloroplasts are distinguished from other types of plastids by their green color, which results from the presence of two major types of pigments in higher plants and green algae, chlorophyll a (Chla ) and chlorophyll b (Chlb )
In the Secondary structure analysis of protein, we found that when amino acid changed encodes a predicted isoform of triose phosphate isomerase
Leaf color mutations usually affect the photosynthetic efficiency of plants, resulting in poor growth and economic losses
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Most photosynthesis products are stored in the seeds as storage reserves which will be used to support postgerminative seedling establishment until chloroplast and leaf development are complete. Chloroplast morphology and starch synthesis were defective in the mutant [3] These observations demonstrated that pdTPI plays an essential role in seedling establishment and chloroplast development in A. thaliana. Leaf color mutants are ideal materials for studying pigment metabolism, chloroplast development and differentiation, and photosynthesis. The cucumber virescent-yellow leaf (vyl) mutant has virescent, yellow-green young leaves, caused by a mutation in the CsVYL gene that encodes a DnaJ-like zinc finger protein [7]. YL2.1 by map-based cloning and showed that it encodes ptTPI in cucumber This finding can help us to understand the underlying mechanisms of chlorophyll biosynthesis and chloroplast development
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