Birth certificates were issued by the New Plant Variety Protection Office of China's Ministry of Agriculture on January 1 to two new plant species, Bioroad Pearl 18 and Bioroad Pearl 216, which were created by hybridizing pea and corn chromosomes. The achievements are just two among those Chinese scientists can lay claim to as the nation establishes itself as a pioneer in chromosome hybridization technology.

The family tree

In the past, claims of crossbreeding between two species from such distant plant families would have been met with ridicule. A widely accepted maxim is that distant hybridization will always cause sterility. However, Chinese scientist Zhu Peikun, founder and chief scientist of Shenzhen Bioroad Biotechnology Co. Ltd. in Shenzhen, south China's Guangdong Province, has proved this false.

At the end of 2014, experts from Shanghai-based Fudan University and the University of Hong Kong conducted an immunoelectrophoresis, biochemically analyzing Bioroad's samples. Fluorescence imaging of in situ hybridization between pea and corn clearly showed that the chromosomes of the two crops had been brought together to produce a new chromosome type. That signified the official dawning of a new era in which man can modify any graminaceous crop.

Zhu, the forerunner of plant chromosome hybridization theory, began his research in 1982. In the beginning, he wanted to crossbreed cole and garlic to protect the former from aphids by giving it the smell of garlic.

After graduating from Fudan University's Department of Biology, he went to teach at his alma mater. Since 1986, he had been doing research in the University of Minnesota in the United States and the Hong Kong University of Science and Technology before returning to China's mainland in 2001. In that year, he made a breakthrough in chromosome hybridization by crossbreeding higher plants of different species. In 2011, Shandong Science and Technology Publishing House published his book Chromosome Hybridization in Higher Plants, an academic insight into chromosome hybridization technology.

A biotech breakthrough

In the past, hybridization usually occurred between different varieties of the same species. Zhu's research focuses on introducing a chromosome from a plant species into the cells of a distant species in order to produce a new type of plant with a hybridized chromosome. Theoretically, with this technology, humans can crossbreed any two species of higher plants to produce a new variety.

Zhu says by crossbreeding crops with plants that can stand droughts or saline environments better - such as cordgrass and camel thorn - they can create new crops that can be grown in saline or even slightly alkaline land. Crossbreeding high-nutrition crops with high-yield ones can produce high-yield and nutritious new crops, as was the case when flax and corn were hybridized.

Zhu has created more than 100 new crops by combining pairs such as pea and corn, wheat and corn, sorghum and rice, corn and rice, as well as corn and wheat. By 2009, the Ministry of Agriculture had issued certificates for new plant varieties for his rice-corn and wheat-corn splices.

Biochemical analysis of flax-corn grown in northwest China's Shaanxi Province showed that the content of its oleic acid, a common monounsaturated fat in the human diet, has increased by 26.81 percent, which is higher than that of ordinary corn, representing a significant improvement over corn's original nutritional value.

There are three major ways in which to create a new plant variety: pollination, cell fusion and chromosome hybridization. Pollination can be achieved between different varieties of the same plant species, such as between different varieties of rice, and between different species or genuses, such as between the apple and pear. Cell fusion is when the protoplasts of plants from different species or families are artificially combined inside a cell, after which the cell is cultured and grown into a full-sized plant.

In 1972, American scientist Peter S. Carlson fused the protoplasts of two tobacco varieties - Nicotiana glauca and Nicotiana langsdorfii - to produce a hybrid, yet there was no evidence to demonstrate that the chromosomes in the cells were hybridized.

Chromosome hybridization technology differs from sexual hybridization in that it directly brings new chromosomes or their fragments into the cells of receptors to mix with the existing chromosomes, which will in turn produce a new hybrid chromosome.

Zhu said that although synthetic chromosome belongs to a eukaryote at the lowest level, the technology is still a milestone in synthetic biology.

(The author is a journalist with China Today magazine)