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In "Control of seed mass and seed yield by the floral homeotic gene
APETALA2," Dr. Diane Jofuku of the University of California, Santa Cruz and
colleagues demonstrate that the gene APETALA2 (AP2) also controls seed size
and weight. AP2 is best known as a regulator of flower organ identity and
development in Arabidopsis. Their findings are published in the February 22,
2005 issue of the Proceedings of the National Academy of Sciences.

By mutating AP2 in Arabidopsis plants and causing the gene to be expressed
in much lower quantities, Jofuku's research team found that average seed
mass significantly increased to as much as 104% greater than wild-type
controls. Seed weight also increased by as much as 104%. These increases,
they found, were due in part to increases in total seed protein and oil; for
instance, the mutant seeds showed a 37-57% increase in the levels of
lignoceric acid (C24:0).

Seed mass and size are good indicators of seedling survival and vigor upon
germination of many plant species. Larger seeds can mean increased tolerance
to flooding and insect predation. These advantages thus make it important to
identify what genes are involved in determining seed size and mass, and how
they may be manipulated to produce desirable agronomic traits.

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