Scientists Sequence Sweet Orange Genome

Mar 26, 2012     Email"> PrintText Size

Chinese scientists have sequenced the genome of the sweet orange (Citrus sinensis), an achievement expected to help scientists understand the complex genetic make-up of the crop in order to improve its quality and yield, according to researchers with Central China Agricultural University in Wuhan, capital of Hubei province.

After a year's effort, a team of horticulture, genomics and bioinformatics experts from the university successfully assembled and annotated the genome sequence of the plant, marking the first time that Chinese scientists have independently determined the genome sequence of a fruit crop.

Deng Xiuxin, an academician with the Chinese Academy of Engineering and the leader of the research team, said that the sequencing of the genome marks the establishment of an ideal research platform for biotechnology and genetic engineering in China, and it is also gravely important for improving breeding and upgrading the crop's industrial competitiveness.

Breeds of citrus are among the most widely grown fruit crops in the world. The sweet orange, which originated in China, is the most commonly grown fruit tree in the world, and its production accounts for about 60 percent of total citrus production.

The sweet orange, mostly poly-embryonic, is highly heterozygous, which means it has dissimilar pairs of genes for any hereditary characteristic, and is plagued by sterility. Therefore, determining its genetic make-up can provide a sound scientific basis for genetic and breed development work, according to Xu Qiang, an expert with Central China Agricultural University.

China is the world's largest grower of citrus, and Chinese people have been cultivating citrus crops for 4,000 years. Statistics from the Ministry of Agriculture show that China produced 26.45 million tonnes of citrus across 2.21 million hectares in 2010.

Of the more than 80 types of citrus species grown in China, 40 percent are not native to China, and half of the country's fruit production is generated from foreign breeds, Deng said, adding that China has been eager to see breakthroughs in the genetic research of citrus in order to speed up the improvement of China's own citrus breeds.

Deng compared sequencing the genome of the sweet orange to opening the "black box" of the crop's life activities, a move that could facilitate the improvement of many of the fruit's traits, including color, taste, yields and disease resistance.

Xu said the researchers launched a website for the sweet orange genome sequence (http://citrus.hzau.edu.cn) on Wednesday to provide free data analysis for academic research.

The world's first human genome sequence map was finished in June 2000. From 2000 to 2009, scientists across the world have drawn whole genome sequence maps for 1,100 species, averaging 118 a year.

Chinese scientists have completed genome sequencing for rice, domesticated silkworms, chickens, oysters as well as endangered animals such as the giant panda and Tibetan antelope.

(Source: Xinhua)