Citrus Breeding: million years of evolution

Abstract

Citrus fruits are one of the most widespread fruit crops worldwide. They constitute a very complex group of genotypes with a great phenotypic diversity. Originally from southeast Asia, the oldest ancestors date back approximately 20 million years. Since then, the genetic improvement of citrus fruit has taken place due to a series of events, many unknown, characterized primarily by hybridization, mutation and natural and human selection. The first systematic improvement programs began in 1893 in Florida, USA, followed by numerous programs around the world. Citrus 
breeding is a long and complex task which has evolved from the simple selection of outstanding genotypes obtained by using classic methods to new biotechnological approaches. Thus, through the use of molecular biology, genomics and genetic engineering, it has been possible to overcome several limitations associated with the complex biology of citrus and gain significant progress regarding citrus fruit characteristics and improvement. This paper reviews citrus breeding evolution and summarizes different approaches used and the results obtained.