阅读理解。
A team of Japanese scientists has discovered genes that enable rice to survive high water, providing
hope for better rice production in lowland areas that are affected by flooding.
The genes, called SNORKEL genes, help rice grow longer stems to deal with higher water levels.
Deepwater rice generally produces low-yield (低产的) rice plants. But the researchers report they have
succeeded in introducing the genes to rice varieties that are higher-yield.
According to the report, as water levels rise, accumulation of the plant hormone (激素) ethylene
(乙烯) makes the SNORKEL genes start working, making stem growth more rapid. When the
researchers introduced the genes into rice that does not normally survive in deep water, they were able
to rescue the plants from drowning.
Motoyuki Ashikari, who headed the project, said his team is-hoping to use the gene on long grain
rice widely used in Southeast Asian to help stabilize production in flood-prone (易受洪水袭击的)
areas where rice with the flood-resistant gene is low in production ---about one---third to one-quarter
that of regular rice.
" Scientifically, the gene that we found is rare but clear proof of a biological ability to adapt to a harsh
environment," he said. "It's a genetic strategy specifically to survive flooding."
High water levels in rice field can be a serious problem. In some areas, rains can cause water levels
to rise dangerously high during the growing season and flash flooding can fully submerge plants for days
or even weeks.
Rice is a main food for billions, and while productivity has increased dramatically since the 1960s,
yields must be doubled to meet projected requirements by 2050. More than 30 percent of Asian and
40 percent of African rice land is either lowland field or deepwater field.
Laurentius of Utrecht University said the study is significant because high-yield rice varieties cannot
survive extremes of floods. "The introduction of these genes into high-yield varieties, using advanced
breeding strategies, promises to improve the quality and quantity of rice," he said.
1. What is the main character of SNORKEL genes?
A. They prevent rice from being attacked by various diseases.
B. They help rice grow taller in highland regions.
C. They make rice grow tall enough to survive in deep water.
D. They make rice be ripe within a shorter time.
2. According to Ashikari, the rice with the gene his team found ______.
A. will be helpful for Southeast Asia
B. has been widely used in Southeast Asia
C. will be one third more expensive than regular rice
D. is lower in production than regular rice
3. The underlined word"submerge"in the sixth paragraph probably means _____.
A. cover
B. damage
C. produce
D. kill
4. What Laurentius said in the last paragraph suggests that_____.
A. rice will be planted on the farmland everywhere in the future
B. rice with SNORKEL genes will be of high quality in the future
C. high-yield rice varieties are not common nowadays
D. the quality of rice is difficult to improve
