A five-volume Chromosome Atlas of Major Economic Plants Genome in China was completed and published recently. The atlas is the first of its kind in the world.

DEDICATED: Professor Chen Ruiyang makes a plant chromosome sample(YANG ZONGYOU)

The atlas has basically covered the chromosome data of all cultivated and wild plants and their kin species in China. It includes chromosome data of some 4,000 economic plants found in China during the period of 1978-2008. It maps the chromosomes of China's fruit trees, crop plants and their wild relatives, bamboo, garden plants and medicinal plants. The age of some precious wild plant species exceeds 5,000 years.

"China is the oldest and largest origin of many crops in the world. Today, many cultivated and wild plants and their kin species grow in China, such as wild rice, wild soybean, wild tea plant and other wild fruit trees," said Chen Ruiyang, the principal author of the plant chromosome atlas and a professor at the College of Life Sciences of Nankai University in Tianjin.

Every living organism has many genes. A gene is the basic unit of heredity. Genes hold the information that enables living things to pass on traits to their offspring. Different organs or cells in one plant hold identical hereditary information. Genes are evolving with the development of the biological system and individual living creature. Individuals of the same species have different genes.

A chromosome is an organized structure of DNA and proteins found in cells. Chromosome contains genes and carries hereditary information, and it controls heredity and mutation, reproduction and growth. The number, shape, structure and behavior of chromosome are controlled by genes. The plant chromosome atlas marks the position of every chromosome, and serves as a registration book for plants.

"The origin of species can be studied from different perspectives. We proceed from chromosomes. From chromosomes, we can see the relationship between plants," Chen said.

Several branches of biology such as genetics, cellular taxonomy, species biology and molecular cytogenetics are based on the study of chromosomes. The plant chromosome atlas compiled by Chen has provided valuable reference material for the study of the above-mentioned branches of biology, said Hong Deyuan, an academician at the Institute of Botany, Chinese Academy of Sciences (CAS) , in the preface of the atlas.

Actually, the atlas is not only of significant research value, but also of great applied value. It can be used to guide agricultural production and the forestry industry. For instance, it facilitates the crossbreeding and cultivation of plants.

Chen's study sheds new light on the categorization, origin and evolution of major plants cultivated in China. Moreover, researchers found 271 new polyploids, polyploid complexes, and cell types of economic and scientific value.

A polyploid is a plant with three or more sets of chromosomes. Polyploids can be created in two ways. If the chromosome duplicates but the cell does not, then a cell will have multiple chromosomes. This gives birth to autopolyploids; crossbreeding can also produce polyploids, and polyploids created in this way are called allopolyploids.