Precocious flowering of juvenile citrus induced by a viral vector based on citrus leaf blotch virus: A new tool for genetics and breeding

The long juvenile period of citrus trees (often more than six years) has hindered genetic improvement by traditional breeding methods and genetic studies. In this work we have developed a biotechnology tool to promote transition from the vegetative to the reproductive phase in juvenile citrus plants by expression of the Arabidopsis thaliana or citrus FLOWERING LOCUS T (FT) genes using a Citrus leaf blotch virus-based vector (clbvINpr-AtFT and clbvINpr-CiFT, respectively). Citrus plants of different genotypes graft inoculated with either of these vectors started flowering within four to six months, with no alteration of the plant architecture, leaf, flower or fruit morphology in comparison with non-inoculated adult plants. The vector did not integrate in or recombine with the plant genome nor was it pollen or vector transmissible, albeit seed transmission at low rate was detected. The clbvINpr-AtFT is very stable and flowering was observed over a period of at least five years. Precocious flowering of juvenile citrus plants after vector infection provides a helpful and safe tool to dramatically speed up genetic studies and breeding programs. This article is protected by copyright. All rights reserved.