Canola, developed in Canada is a variety of the rapeseed or oilseed rape
plant, which is among the most popular vegetable oil crops worldwide. Miller
and colleagues grew about 100 rapeseed varieties, each of which had been
previously sequenced at the transcriptome level-revealing which genes each
variety expressed, and at what levels-and showing huge variation in gene
activity across varieties. Miller also harvested and weighed seeds from each
variety, with some seeds heavier than others, a proxy for their oil content.
Miller's team compared differences in seed weight and found that one gene,
UPL3, was highly active in plants with light seeds, suggesting that UPL3's
protein might be involved in seed development. The researchers then examined
mutants with nonfunctional UPL3 in Arabidopsis model and found that their
seeds were 10 percent heavier than wild-type seeds. To find out how UPL3
influenced seed weight, the researchers looked for genes already known to be
involved in seed development. They found three genes, all regulated by the
same protein, LEC2, a transcription factor that increases their expression,
leading to larger and oilier seeds.