Man, the Creator

By staff reporter LI WUZHOU

ON January 1, the New Plant Variety Protection Office of China’s Ministry of Agriculture issued “birth certificates” to two new plant species, Bioroad Pearl 18 and Bioroad Pearl 216, which were created by hybridizing the chromosomes of peas and corn. The achievements are just two among many that 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 at Shenzhen Bioroad Biotechnology Co., Ltd. in Shenzhen, South China’s Guangdong Province, has proved this to be false.

In past years experts from Shanghai-based Fudan University and Hong Kong University proved that peas and corn had indeed been successfully crossbred into a new crop variety after conducting an immunoelectrophoresis analysis of Bioroad’s samples. That heralded the official dawning of a new era in which man can modify any graminaceous crop.

Fluorescence imaging photos of in situ hybridiz

ation of chromosomes between peas and corn clearly showed that the chromosomes of the two crops were successfully brought together to produce a new chromosome type.

Zhu, the forerunner of higher plant chromosome hybridization, began his research in this field in 1982. In the beginning, he wanted to crossbreed cabbage and garlic, which are also distantly related. He hoped to protect the cabbage from aphids by making them smell of garlic.

After graduating from the Department of Biology at Fudan University, he went on to teach at his alma mater. Since 1986, he had conducted research at the University of Minnesota in the United States and the Hong Kong University of Science and Technology. He returned 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, the 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 one plant species into the cells of another, 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 plant to produce a new plant variety.

Zhu said that by crossbreeding crops with plants that have a stronger tolerance for droughts or saline environments, such as cordgrass and camel thorn, scientists can create new crops that can be cultivated in saline or even slightly alkaline land. Crossbreeding high-nutrition crops with high-yield crops can produce high yielding and nutritious new crops, as was the case when flax and corn were hybridized.

So far, Zhu has created more than 100 new crops by combining pairs such as peas and corn, wheat and corn, sorghum and rice, corn and rice, and corn and wheat. By 2009, the Ministry of Agriculture had already 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 the nutritional value of corn.

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 different varieties of rice; and between different species or genera, such as apples and pears. Cell fusion is when the protoplasts of plants from different species or families are artificially combined inside a cell, after which the plant cell is then 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 of the pair, 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 the synthetic chromosome belongs to an eukaryote of the lowest level, the technology is still a milestone in synthetic biology.