Rice in the Veins


2009 / 2月

Chang Chiung-fang /photos courtesy of Jimmy Lin /tr. by David Mayer

Humans have engaged in wet rice ag-riculture since as far back as 10,000 years ago. Today, the practice has spread across the entire planet, and the harvest constitutes the number-one staple in the diets of some 3.5 billion people worldwide.

During the "green revolution" of the 1960s, dwarfing of rice and wheat resulted in dramatically better yields (as dwarf plants use more of their energy for filling the grain than in growing taller), but the gains in output have not kept pace since then with population growth. To make matters worse, the United States triggered a global grain shortage and spiraling prices in 2006 when it diverted 14% of its corn harvest to ethanol production. Even major rice-producing nations such as Vietnam, Thailand, and India ordered rice exports to be halted or reduced.

Luckily, biotechnology is progressing at leaps and bounds. Scientists are working on transgenic crops to find more effective means of producing food and energy. The "second green revolution" is barreling ahead, and wet rice agriculture is once again a key focal point of research.

Yu Su-may, a distinguished research fellow at the Academia Sinica's Institute of Molecular Biology and a pioneer in the field of rice genetics in Taiwan, has obtained more patents in her field than anyone else.

So what is so engrossing about wet rice research? Why is Yu Su-may so hopelessly addicted to it?

On the first day of 2009, while virtually all of us were sleeping off the previous night's celebrations, Yu toiled away alone in the laboratory, where she works year-round without vacation on preparations for the bioenergy segment of the Executive Yuan's national energy plan.

But paddy rice is the true love of her life, and at the mere mention of it Yu's eyes light up.

Unfading memories

Those of us from an urban background may not have any particularly strong emotional reaction to rice or rice fields, but the waving fields of golden grain in the feature single of Jay Chou's album Capricorn are for Yu more than just a pretty bit of film; they are a vivid memory that has hovered in her consciousness since childhood.

Born to a farming family in Taichung County's Waipu Township, Yu grew up watching the rice fields transform with the four seasons. It left an indelible mark in her young mind, but even to her it must seem a bit ironic that going off for advanced schooling in Taipei and embarking upon a career in biotechnology should have taken her back once again to the rice fields of her youth.

"I've been studying wet rice agriculture all my life," says Yu. She did her master's thesis on rice paddy diseases. In her doctoral and post-doctoral research she focused on rice-paddy weed control and rice seed germination. After entering the Institute of Molecular Biology she began looking into "molecular farming" issues, such as how sugars and hormones can be used to regulate the growth of paddy rice and make rice paddies more productive. Then she single-handedly set up Taiwan's Rice T-DNA Insertion Mutant Library, only the fourth such library in the world after ones in China, South Korea, and France.

Apart from the emotional tug of her childhood memories, the central importance of rice to Yu's career also makes perfect sense from a professional angle because rice is a hot topic in plant molecular biology.

The rice genome is small (there are only 12 chromosomes and some 37,000 genes, while the genomes of corn and wheat are six and 40 times larger, respectively), and so has provided an important model for the study of plant genome functions. It is also the first crop genome to be sequenced. Researchers in Taiwan and nine other nations collaborated on the rice genome sequencing project, which was finally completed in 2005 after seven years. Since completion of the sequencing, rice researchers have begun studying the functions of each gene. According to Yu, less than 1% of all rice genes have been decoded to date.

Genetic database

The easiest way to translate a gene is to disrupt it and cause it to undergo genetic transformation. Yu is the first person in the world to successfully achieve Agrobacterium-mediated transformation of monocotyledonous plants.

A "monocotyledonous plant" is a flowering plant having a single cotyledon (seed leaf) in the seed (the presence of just one cotyledon is most obvious when the plant is just beginning to sprout). Monocots are chiefly herbaceous and have no cambium, which is why the stem is not capable of the secondary growth seen in woody plants. Dicots, in contrast, have two cotyledons. Their vascular bundles are arranged in a ring shape, and they have a cambium and develop a tree-ring growth pattern. The separation between monocots and dicots was complete some 200 million years ago, and for some reason gene transfer is more difficult to achieve in monocots. Yu conjectures that it may be due to their metabolites.

Agrobacterium has been dubbed a "natural genetic engineer." It is endemic to soil-borne plant pathogens, and frequently causes crown gall tumors and hairy root disease. Yu uses Agrobacterium as a medium to transfer a fragment of exogenous genetic material (T-DNA, short for "transferred DNA") into a host plant's nuclear DNA genome.

Yu studies the functions of paddy-rice genes by random insertion, either disrupting the genes (by inserting material directly into them) or activating them (by inserting material between two genes).

"Whether you disrupt or activate a gene, once a mutation is generated, it will affect the generation of proteins and cause either suppression or overexpression of a particular function, and the gene characteristic is changed," says Yu, citing mutant paddy rice as an example. Some stems are deformed, some are short, and some grow taller than a man. The spikes may stand up straight, like wheat, and the color of the leaves may be changed. To date, this work has already resulted in the addition of over 60,000 types of mutant paddy rice to Taiwan's Rice T-DNA Insertion Mutant Library. Some types may lack resistance to flooding, drought, or cold weather.

Each mutation produced by Yu's laboratory is delivered to the Council of Agriculture's Agricultural Research Institute for isolated field testing under rigorously controlled conditions (to prevent seeds from escaping and "contaminating" normal rice crops). After two generations of breeding, the seeds are collected and delivered to the national Mutant Library for safekeeping.

In addition to preserving different strains of rice, the Institute of Molecular Biology is also working to further decode the rice genome by finding disrupted genes, recording their characteristics and other biodata, and entering the information into a database. The genomic sequences of 30,000 mutations have been identified and announced on the Web. Interested researchers can apply to the Rice T-DNA Insertion Mutant Library for seeds to use in their own research.

Yu has identified 20 or 30 paddy-rice genes with special functions. Some make for bigger rice grains, some accelerate growth, and others enable rice to grow in adverse environments by making it more resistant to drought, cold, or saline soils.

It takes a promoter

One key focus of Yu's research is the use of enzyme staining to identify promoters of different gene functions.

"Promoters are very important," says Yu. They are required for genes to express specific functions. Tissue-specific genes and growth phase-regulated genes, for example, require promoters to direct their expression.

By identifying different promoters, a scientist can cause a special gene to be expressed only at a given location or at specific times. Take the nematode resistance gene, for example. Nematodes only infect rice plants via their roots, so the gene need only be expressed in the roots, not in the seeds. This is important, since consumers who are concerned about genetically modified crops need not worry that the grains of rice they eat contain transgenic protein.

The drought resistance gene is another good example. If it were expressed all the time, the plant would always be in drought resistance mode; to stay alive, it would remain stunted, which is no way to get a bumper crop. Scientists must find a promoter to direct its expression, so that the rice will grow well under normal weather conditions and put on the brakes only when water is scarce.

GM to rescue the hungry?

The world faces a grain shortage in the making, and the use of genetic engineering to make paddy rice more resistant to disease and adverse conditions is a means of addressing the problem.

World population is expected to reach 9 billion by the year 2050, and half the people on our planet depend on rice as their main food staple. Demand grew from 2.56 million metric tons in 1965 to 6 million tons in 2006, and is projected to reach 7.5 million tons by 2020.

Even as populations grow, the global supply of arable land declines due to industrial pollution, desertification, salination (e.g. by accumulation of fertilizer, or by seawater permeation of soil), erosion, and other factors. The question of how to produce enough grains to feed the world is emerging as an enormous challenge. Scientists believe that genetic modification is of key importance in efforts to resolve the grain shortage because it can increase crop yields and lower the cost of cultivation.

Raising crop productivity and improving resistance to diseases and pests will greatly reduce costs by enabling farmers to cut down on the use of chemical herbicides, pesticides, and fertilizers. Statistics indicate that the use of agricultural chemicals dropped by 14% (or 172.5 billion tons) from 1996, when GM crops were first introduced, to 2004.

"Disease and pest resistance is the most important thing here in Taiwan," says Yu. Living as we do on a small, densely populated island with a humid climate and an abundance of diseases and pests, farmers make heavy use of agricultural chemicals. Indeed, they rank No. 1 in Asia on this score. But if we can bring about widespread use of disease-resistant GM crops, explains Yu, we can resolve this longstanding problem.

And improving the resistance of crops to drought, salinity, and cold will increase arable land area, as crops could be planted in locations that were not formerly suitable, such as low-lying coastal zones subject to seawater incursion, for example, or areas with cold weather.

Besides food, many also hope to use GM crops to resolve the energy crisis.

Yu points out that converting the cellulose in crops to biofuels is quite feasible in theory, but the technology is still under development.

Using an architectural analogy, she likens cellulose to steel rebar, while lignin (which fills the spaces in a plant's cell wall between cellulose, hemicellulose, and pectin components) corresponds to the concrete. These two intertwined elements enable a plant to stand up straight, but the "rebar and concrete" just get in the way when we try to extract fuel from biomass. Cellulose has to be removed in order to break down sugar and process it into ethanol. Strong acids, high temperature, and high pressure are required to destroy the "rebar and concrete," but the acids generate pollution, while a huge amount of energy is consumed to produce the high temperature and pressure. The process is neither environmentally friendly nor economic.

So what kind of "smart crops" should we be growing for energy extraction? Yu believes that paddy rice, wheat, and sugarcane can all be modified from head to toe to suit the purpose. With paddy rice, for example, everything other than the edible seeds has always been seen as waste. Indeed, the rice stalk is generally burnt, causing air pollution, but in fact it is high-quality cellulose that in the future promises to be a "star performer" in the biofuels industry.

Molecular farming

In addition to providing food and energy, genetic engineering can also be used to make rice produce proteins and enzymes with medical or industrial applications. The pursuit is often referred to as "molecular farming," and is a key focus of scientific research.

The "golden rice" that is now being tested at the International Rice Research Institute in the Philippines and is scheduled to hit the market in another two or three years, is a typical example of molecular farming.

Swiss scientists Ingo Potrykus and Peter Beyer announced the development of golden rice in 2000. The pair used gene transfer to produce rice with a high level of beta carotene, which is converted to vitamin A in the body. Every year some 127 million babies and 7 million young mothers contract blindness or even die due to a lack of vitamin A, but golden rice promises to provide a very effective way of solving the problem.

Yu has achieved numerous breakthroughs in molecular paddy rice farming over the years. One such breakthrough came with the development of phytase-enhanced rice.

Rice containing transgenic phytase helps the body break down and absorb phosphorus. Yu explains that most pigs and poultry mainly feed on corn and soybeans. The phosphorus in their food is generally chemically bound to other elements and cannot be absorbed in the intestines, so it is mostly passed out with the animals' stools. A lack of phosphorus affects an animal's skeletal development, and runoff phosphorus can pollute ground in and around the farm while causing eutrophication of nearby lakes and ponds. But adding phytase-enhanced rice to the animals' feed helps livestock absorb the phosphorus, thus solving the problems described above.

In addition to livestock and the environment, phytase is also for humans.

"Phytase is especially good for vegetarians," says Yu, because they eat a lot of beans. Phytase-enhanced rice helps them break down the phosphorus, which is good for digestion.

In 2000, Yu transferred the technology for producing phytase-enhanced rice to Ingene Biotechnology Co.. However, to everyone's surprise, the Council of Agriculture has had three successive reviewers on the project, but the rice has yet to pass field testing eight years on.

Taiwan exports rice to Japan, the only developed nation that has not approved the planting of GM crops. The term "genetically modified" makes Japanese people uneasy, and Taiwan's Council of Agriculture is therefore concerned that allowing GM rice to be grown could restrict Taiwan's rice exports to Japan. This is one reason why the authorities in Taiwan have been so reluctant to allow phytase-enhanced rice to pass field testing. However, Chen Yu-hui, a professor in the Department of Agricultural Economics at National Taiwan University, has published a report on the economic returns generated by phytase-enhanced rice and concluded that once the rice is approved for the market, the value of phytase-enhanced rice output will exceed the value of rice exports to Japan.

A cry in the wilderness

After eight years of struggle, Yu no longer holds out hope of seeing her research breakthroughs put into practice on farms in Taiwan, so she has turned her attention overseas, and is beginning to cooperate with foreign biotech firms.

BASF, headquartered on Germany's Rhine River and the largest agrochemicals company in the world, has signed a cooperation agreement with the Academia Sinica. Under the agreement, BASF is providing funding for research on 30 genes related to paddy rice yields. As soon as Yu's laboratory identifies a gene's function, BASF can immediately begin licensed use of the gene. In addition, multinational giant Monsanto is very interested in a promoter that directs gene expression at the seedling phase, and will receive a license very soon.

Yu, who leads the pack in Taiwan with over 20 plant-related patents, points out a big field testing backlog at the Council of Agriculture, and laments that the lack of approvals is stifling the prospects for development of Taiwan's agricultural biotech industry.

When the Academia Sinica first hooked up with BASF, 100 genes were originally selected for research, but the number was slashed to 30 in the end because teams from other countries had already filed patent claims on the rest.

"In another two or three years, Taiwan is not going to have any shot at leadership in high-tech agriculture," complains Yu, ruefully noting that once all the patents have been taken, researchers in Taiwan won't be able to study anything without infringing on someone's patent. Golden rice offers a glimpse of just how competitive things are in this industry: the new rice is being developed with the humanitarian aim of helping impoverished mothers and children, yet research work has been held up by more than 20 patent-related matters.

Yu wistfully recalls that the "Dee-geo-woo-gen" and "Taipei 309" rice strains that propelled the first green revolution in the 1960s were developed from Taiwanese paddy rice. But now our pussyfooting policymakers threaten to stand between Taiwan's paddy rice researchers and their chance at leadership in the field; it is not hard to imagine the frustration that Yu must be feeling. Will anyone heed her urgent cries?



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瑞士科學家Ingo Potrykus與Peter Beyer在2000年發表的「黃金米」,成功地以基因轉殖方式,讓米含有較高的β胡蘿蔔素,食用後可轉化為維生素A,以有效解決全球1.27億兒童及700萬孕婦因維他命A缺乏而導致眼盲,甚至死亡的問題。















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