International Team Sequences Genome of Sweet Orange

An international team of scientists from China and Singapore have sequenced the genome of sweet orange (Citrus sinensis). Scientists from Singapore's Agency for Science, Technology and Research (A*STAR), Genome Institute Singapore (GIS), and China's Huazhong Agricultural University and their colleagues compared the sweet orange's genome with pummelo (C. grandis) and mandarin (C. reticulata) using simple sequence repeat and single-nucleotide polymorphism markers. The team found out that one quarter of the sweet orange's markers matched those from pummelo and three quarters matched mandarin.

The research team also studied the sequence data to understand the production of Vitamin C, one of the crop's most important traits. They searched for genes similar to GalUR, which produces a key enzyme in the vitamin C production pathway and found 18 copies that are highly expressed in orange fruits. The availability of sweet orange genome will now facilitate the study of other important traits, including disease resistance, flavor, sugar content, and fruit color. Xiaoan Ruan of GIS said that "The findings provide new tools and approaches for future plant breeding using genetic modification or engineering for high-yield vitamin C production."

The team presented the results of their study in the journal Nature Genetics. The paper can be accessed at http://www.nature.com/ng/journal/v45/n1/full/ng.2472.html (doi:10.1038/ng.2472).