Seed size is controlled by maternally produced small RNAs: research

Apr 11, 2012
Small RNAs affect development of seeds. These are arabidopsis seeds three, four, five, six and seven days after pollination (left to right). First row: diploid seeds. Second row: seeds from a cross between a diploid mother and tetraploid father. Third row: seeds from a cross between a tetraploid mother and diploid father. Fourth row: tetraploid seeds. Note that seeds in the third row (five to six days after pollination) are much smaller than those in the second row as a result of increased maternally inherited small RNAs. Credit: Z. Jeff Chen, The University of Texas at Austin

Seed size is controlled by small RNA molecules inherited from a plant's mother, a discovery from scientists at The University of Texas at Austin that has implications for agriculture and understanding plant evolution.

"Crop seeds provide nearly 70 to 80 percent of calories and 60 to 70 percent of all proteins consumed by the human population," said Z. Jeff Chen, the D.J. Sibley Centennial Professor in Plant at The University of Texas at Austin. "Seed production is obviously very important for agriculture and ."

Chen and his colleagues, including David Baulcombe at the University of Cambridge, provide the first genetic evidence that seed development is controlled by maternally inherited "small interfering RNAs," or siRNAs.

They published their research April 3 in the journal PNAS.

SiRNAs are known to control a number of aspects of growth and development in . The researchers used Arabidopsis, a rapidly growing flowering plant in the mustard family, for the study.

In this case, the researchers found that the siRNAs influence the development of a seed's , which is the part of the seed that provides nutrients to the developing , much like the placenta in mammals. The endosperm is also the source for most of the nutritional content of the seed for humans and animals.

Despite the importance of the endosperm, little has been known about the that govern its growth.

In flowering , the embryo is formed by fusion of one paternal and one maternal genome, while the endosperm combines one paternal and two maternal genomes. This process of embryo and endosperm formation is known as "double fertilization."

The scientists found that when a female plant with a duplicate genome (known as a tetraploid) is crossed with a male plant with a normal genome (called a diploid), not only is there an increase in the maternal genome in their offspring's seed endosperm, but there is also an associated increase in maternal siRNAs.

Those maternal siRNAs decrease the expression of genes that lead to larger endosperm growth, meaning that the siRNAs create smaller seeds.

"Now we understand that siRNAs play a large role in sensing maternal and paternal genome imbalance and controlling seed development, and that maternal control is important," said Chen.

The researchers are working to find out how exactly siRNAs regulate gene expression in the endosperm and embryo and how they control seed size. These new findings will enable scientists to develop biotechnological tools for improving seed production and crop yield.

But Chen cautioned that "bigger isn't always better." In fact, in his experiments, seeds lacking the control of the maternally inherited siRNAs grew so large that they collapsed.

Explore further: Chickens to chili peppers: Scientists search for the first genetic engineers

Related Stories

Maize gene could lead to bumper harvest

Jan 16, 2012

(PhysOrg.com) -- The discovery of a new ‘provisioning’ gene in maize plants that regulates the transfer of nutrients from the plant to the seed could lead to increased crop yields and improve food ...

Recommended for you

Deadly human pathogen Cryptococcus fully sequenced

13 hours ago

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Building better soybeans for a hot, dry, hungry world

Apr 16, 2014

(Phys.org) —A new study shows that soybean plants can be redesigned to increase crop yields while requiring less water and helping to offset greenhouse gas warming. The study is the first to demonstrate ...

User comments : 0

More news stories

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

Venture investments jump to $9.5B in 1Q

Funding for U.S. startup companies soared 57 percent in the first quarter to a level not seen since 2001, as venture capitalists piled more money into an increasing number of deals, according to a report due out Friday.