Researchers from the National Centre for Biological Sciences, Tata Institute
of Fundamental Research in India led by Dr. P.V. Shivaprasad investigated if
another form of molecular regulator known as microRNAs are responsible for
the domestication of rice.
The team made a comparison of the microRNA populations of high-yielding
indica rice lines, of wild rice and other traditional rice varieties. They
found that one microRNA species, miR397, accumulated to high levels in the
flag leaves of wild rice, but were very low in other plants analyzed. They
also found that miR397 silenced several members of the laccase gene family,
which encode proteins that promote woody tissue formation for mechanical
strength. By silencing a subset of these genes, miR397 greatly reduced the
formation of woody tissue.
Using genetic engineering techniques, the researchers expressed the gene
coding for miR397 in domesticated rice, which resulted to plants that were
more similar to wild rice plants than to domesticated ones, with long,
spindly stems; narrow, short leaves; few flowering structures; and hardly
any rice grains. These findings suggest the involvement of miRNAs in rice
domestication, particularly in boosting rice production.