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■科學家完全破解粟米的基因序列，除可大增產量，亦能應付全球的糧食危機。資料圖片
美國一隊科學家破解了粟米的基因序列，有助更快開發高產量的粟米。
研究員表示，粟米是全球產量最多的穀類植物，僅次於稻米和高粱。在全球氣候改變下，人口不斷增加，提升粟米生產技術是解決糧食問題的一大步。
由美國密蘇里州聖路易斯華盛頓大學領導的150人專家小組表示，粟米的基因組包括10對染色體，他們確認了3.2萬個基因，是歷來植物基因研究中最多。
與此相比，人類基因組有23對染色體，內有2萬個基因。
華盛頓大學基因組中心主任威爾遜表示：「擁有粟米的全部基因組序列，科學家更易研究出更高產、更耐熱、更耐旱的新品種粟米。」
威爾遜又說﹕「種子公司和粟米基因專家會抓住這些資料，尋找良好的基因，現在他們知道這些基因在哪裡。」
粟米的基因包括23億個DNA鹼基，由英文字母T、C、G、A組成。人類基因亦相差不遠，由29億個鹼基組成。
研究員歷盡艱辛，確認出字母的排列序。他們發現，85%排列都是重複。
華盛頓大學的研究員克利夫頓表示﹕「尋找粟米的基因排列有如在荒蕪的公路上駕車，途中只有零星的路牌。我們只有基本的地圖，但因為基因重複的性質，有些目標位置是錯誤的。能夠確認基因的位置，是眾多科學家的共同努力。」
這個計劃在2005年展開，由美國科學基金會、農業部和能源部資助，經費達2,950萬美元(約2.3億港元)。
全球人口在2050年內會增加23億人，聯合國預測，全球食物產量必須在未來40年間增加7成。
美國是全球最大的粟米生產國，每年產量2億噸，佔全球44%。 ■綜合外電消息 資深翻譯員 羅國偉
Scientists Uncover Corn's Full Genetic Code
A team of US scientists has uncovered the complete genetic code of corn, a discovery that promises to speed the development of higher yielding varieties of corn.
Corn is the third most abundant cereal crop, after rice and sorghum, researchers said. Advances in corn production could mean major steps toward feeding the world's growing population as it struggles with climate change.
The team of 150 experts, led by Washington University in St. Louis, Missouri, said they had identified some 32,000 DNA sequences, or genes, in the 10 chromosomes that make up the genome of maize, the largest of any plant examined so far.
By comparison, the human genome includes 20,000 genes distributed in 23 chromosomes.
"Having the complete genome in hand will make it easier to breed new varieties of corn that produce higher yields or are more tolerant to extreme heat, drought, or other conditions," said Richard Wilson, director of Washington University's Genome Center. "Seed companies and maize geneticists will pounce on this data to find their favorite genes," he said. "Now they'll know exactly where those genes are."
Corn's genetic code contains about 2.3 billion bases of DNA, represented by the letters T, C, G and A. Human genetic code is not far off with 2.9 billion.
After having great difficulty establishing the exact order of the letters, the researchers found that about 85 percent of the sequences are repetitive.
"Sequencing the corn genome was like driving down miles and miles of desolate highway with only sporadically placed sign posts," said researcher Sandra Clifton of Washington University.
"We had a rudimentary map to guide us, but because of the repetitive nature of the genome, some of the landmarks were erroneous. It took the dedicated efforts of many scientists to identify the correct placement of the genes."
The project, which began in 2005, cost 29.5 million dollars and was funded by the National Science Foundation and the US departments of agriculture and energy.
The United Nations predicts that world food output must grow by 70 percent over the next four decades to feed a projected extra 2.3 billion people by 2050.
The US is the world's top producer of corn with 200 million tons a year, or 44 percent of the world's output. ■AFP
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