Cornell University

United States of America, As Represented by the Secretary of Agriculture

Boyce Thompson Institute Inc.

Shan Lu

Li Li

Julia Vrebalov

David F Garvin

Diana M O'Halloran

The cauliflower (L. var.) Or gene is a semi-dominant, single-locus mutation. It induces the accumulation of high levels of beta-carotene in various tissues that are normally devoid of carotenoids, turning them orange. Using a map-based cloning strategy, we identified a single candidate gene representing Or and successfully verified its identity by phenotypic complementation in the wild type cauliflower. The Or gene encodes a plastid membrane protein containing the DnaJ zinc figure domain. A likely gain-of-function mutation from a 4.3-kb retrotransposon insertion in the Or allele confers the orange phenotype in the mutant. Southern blot analysis revealed that Or is a single-copy sequence in the cauliflower genome. High level of expression of the Or gene and the protein was found in very young leaves, curds, and flowers at comparable abundance between wild type and the Or mutant. Or likely functions in regulating the differentiation of some non-photosynthetic plastids into chromoplasts, which provide the deposition 'sink' for carotenoid accumulation. Or orthologs with high degree of sequence homology were found in many other higher plants, including, tomato, maize, and rice. Successful phenotypic complementation of Or inprovides strong evidence that Or can work across species to enhance carotenoid accumulation in other important crops.

Growing community of inventors

Ithaca, NY, United States of America

Shan Lu