NIU professor on team that decodes rice genome

by Tom Parisi

NIU professor Long Mao was among a team of researchers who described the draft sequence of the rice genome in the April 5 issue of the prestigious journal, Science. Cracking virtually the entire genetic code of rice, one of the world's most important crops and a potential genetic blueprint for other cereal crop plants, is considered a benchmark accomplishment in agricultural sciences that could lead to enhanced foods.

NIU professor Long Mao is on team of researchers studying the draft sequence of the rice genome.

"This is the first complete sequence of the rice genome and the first crop genome to be described in publication," said Mao, a professor in the Department of Biological Sciences. "The genetic map for rice will hopefully lead to the development of more nutritious rice, higher yields, more economical means of production and crops that are resistant to disease and more tolerant to harsh growing conditions."

Two groups of scientists published simultaneously in Science on near-complete genetic codes of two common species of rice. Mao was part of the team led by the agribusiness firm Syngenta. In collaboration with Myriad Genetics Inc., Syngenta announced early last year that it had completed the genome map for rice but had not published on the discovery.

"It's as if, a year ago, it was announced we wrote a book," Mao said. "Now people can read the book."

During the past year, the scientists embarked on a more detailed analysis of gene activity and function in the rice genome, described in Science. In addition to an analysis of the genetic composition of rice, comparisons are made to Arabidopsis, the first higher plant to be genetically decoded.

Rice is among the world's most important crops. About one-third of the world's population depends on rice for more than 50 percent of their caloric intake. Mao said rice also is important in genetic terms. It is closely related to cereal crops such as wheat, corn and barley. However, Mao said the rice genome is much smaller than other cereals, making it a logical choice for sequencing. The wheat genome, for example, is 40 times bigger than the rice genome.

The scientists used a method known as whole genome shotgun sequencing in mapping the genome of a rice variety known as Nipponbare, one of two major subspecies. The rice genome is spread across 12 chromosomes and is made up of about 420 million bases of DNA. The researchers also identified genes in rice that have the same origin and perform similar functions in other cereal crops.

"Rice is a model for cereal crops," Mao said. "The genetic map for rice provides us with a critical resource that allows us to better understand the genetic makeup of other crops."

Mao arrived on campus at NIU in August of 2001, after being recruited to bolster the university's program in bioinformatics, an area of study that uses advanced computing techniques to analyze vast amounts of biological data. A year earlier, NIU had become the first university in Illinois to offer a master's degree program with a specialization in bioinformatics.

Previously, Mao served as a postdoctoral fellow at Clemson University, where he worked in the bioinformatics group of the university's Genomics Institute. It was there that he began working on the DNA sequences of rice in a project supported by Syngenta.

Only weeks after arriving at NIU, Mao traveled to California to participate in a detailed analysis of the rice genome in preparation for the new publication. Mao classified and quantified the repetitive sequences of DNA.

"Repetitive sequences are ancient DNA elements that are non-functioning," Mao said. "However, they are an important component for the organization and structure of some chromosomes and they provide important information for studying genome evolution."

The draft assembled sequence of rice covers 93 percent of the 420-megabase genome. It is considered to be 99 percent accurate, when compared with finished segments of the rice genome already sequenced by a public consortium, Mao said. "We now know all the genes in the rice genome, but we don't know where each and every gene is located along each chromosome," he added.

The genetic map is considered a draft because the sequence, to be considered complete, must be 99.9 percent accurate, Mao said.

Mao, whose other research specialty is in the area of tomato genetics, teaches bioinformatics and molecular biology at NIU. His list of previous publications includes a first-authored article in the international journal, Nature.