Scientists identify
gene that may contribute to improved rice yield
By Sara LaJeunesse
Source:
September 29, 2008
Via: CheckBiotech
A team of scientists, including Hong Ma, Penn State
distinguished professor of biology, has identified a gene in rice that controls
the size and weight of rice grains.
The gene may prove to
be useful for breeding high-yield rice and, thus, may benefit the vast number
of people who rely on this staple food for survival. "Our work shows that
it is possible to increase rice's yield by enhancing the expression of a
particular gene," said Ma. The team's results will be published on Sept.
28 in an early online edition of the journal Nature Genetics, and in the
November print issue of the journal.
The researchers first searched for and identified mutant
strains of rice that exhibited underweight grains. "We found a particular
mutant that is defective in its ability to produce normal-sized grains,"
said Zuhua He, a biology professor at the
Next, to test the ability of the GIF1 gene to control the
production of invertase, the team measured the
activity of invertase within a normal strain of rice,
in which the GIF1 gene lacked any mutations, and within a mutant strain of
rice, in which the GIF1 gene contained a mutation that caused a defect in the invertase activity. The scientists found that invertase activity in the mutant strain was only 17 percent
of the activity that was observed in the normal strain, suggesting that the
GIF1 gene does, indeed, control invertase activity.
The team then created transgenic lines of rice in which the GIF1 gene is overexpressed and found that, compared with normal strains, the transgenic rice had larger and heavier grains.
According to Ma, the team was surprised to find that the
GIF1 gene was so specialized in controlling invertase
activity in a particular part of the grain - the vascular tissue, which
transports nutrients, including sugars generated by invertase,
to the developing grain. "The expression pattern was not expected, in part,
because invertase is a general enzyme that is used by
many cell types. In fact, the corresponding gene in wild rice is not expressed
specifically."
The team also found that the GIF1 gene is one of the genes
that were selected during the domestication of rice. "By selectively
growing only those strains of rice with heavier grains, humans for thousands of
years unknowingly have been increasing the frequency of rice populations that
had modifications in the GIF1 gene," said Ma. "This process has
caused GIF1 to be expressed specifically in the vascular tissue and, thus, to
produce larger rice grains," said Ma.
The scientists hope that their findings will help others to
create hybrid varieties of rice that produce even larger grains. In the
meantime, they plan to perform additional analyses that will help them to
understand how other genes might be involved in the process of improving rice
yield. "The goal is to understand what controls grain weight and other
factors, and to look for ways to increase yield," said Ma.
This research was supported by grants from the Ministry of
Science and Technology of China, the National Science Foundation of China and
the Shanghai Institutes for Biological Sciences.
CONTACT:
Barbara Kennedy
814-863-4682
www.science.psu.edu
Source:
greenbio.checkbiotech.org