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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Plant, Soil and Nutrition Research » Research » Publications at this Location » Publication #334111

Title: Fruit color mutants in tomato reveal a function of the plastidial isopentenyl diphosphate isomerase (IDI1) in carotenoid biosynthesis

item PANKRATOV, ILYA - Hebrew University Of Jerusalem
item MCQUINN, RYAN - Boyce Thompson Institute
item SCHWARTZ, JOCHANAN - Hebrew University Of Jerusalem
item BAR, EINAT - Hebrew University Of Jerusalem
item FEI, ZHANJUN - Boyce Thompson Institute
item ZAMIR, DANI - Hebrew University Of Jerusalem
item Giovannoni, James
item HIRSCHBERG, JOSEPH - Hebrew University Of Jerusalem

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2016
Publication Date: 6/11/2016
Citation: Pankratov, I., Mcquinn, R., Schwartz, J., Bar, E., Fei, Z., Zamir, D., Giovannoni, J.J., Hirschberg, J. 2016. Fruit color mutants in tomato reveal a function of the plastidial isopentenyl diphosphate isomerase (IDI1) in carotenoid biosynthesis. Plant Journal. doi: 10.1111/tpj13232.

Interpretive Summary: Carotenoids are molecules widespread in all biological kingdoms. In photosynthetic organisms they play essential roles in light harvesting and photoprotection and in plants, fungi, birds and fish they provide characteristic colorations including for many fleshy fruits such as tomato. In plants, carotenoids also serve as precursors in the biosynthesis of hormones and signaling molecules and volatiles. Here we describe the characterization of tomato mutants lacking a gene encoding a key and early step in carotenoid biosynthesis termed plastidial isopenty diphosphate (IDI1). The phenotypes of these mutants establish functions for IDI1 in greening of leaves in response to light and and suggest that this enzyme serves as an important biochemical regulator of fruit carotenoid biosynthesis leading directly to effects on fruit color and quality.

Technical Abstract: Isoprenoids are a large class of compounds that are present in all living organisms. They are derived from the 5C building blocks isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP). In plants, IPP is synthesized in the cytoplasm from mevalonic acid via the “MVA pathway” and in plastids from 2-C-methyl-D-erythritol 4-phosphate through the “MEP pathway”. The enzyme IPP isomerase (IDI) catalyzes the inter-conversion between IPP and DMAPP. Most plants contain two IDI enzymes, whose functions are characteristically compartmentalized in the cells. Carotenoids are isoprenoids that play essential roles in photosynthesis and provide colors to flowers and fruits. They are synthesized in the plastids via the MEP pathway. Tomato (Solanum lycopersicum) fruits accumulate high levels of the red carotene lycopene. We have identified mutations in tomato that reduce overall carotenoid accumulation in fruits. Four alleles of a locus named FRUIT CAROTENOID DEFICIENT 1 (fcd1) were characterized. Map-based cloning of fcd1 indicated that this gene encodes the plastidial enzyme IDI1. Lack of IDI1 reduced the concentration of carotenoids in fruits, flowers and cotyledons but not in mature leaves. These results indicate that the plastidial IDI plays an important function in carotenoid biosynthesis thus highlighting its role in optimizing the ratio between IPP and DMAPP as precursors for different downstream isoprenoid pathways.