The homeobox gene GLABRA2 affects seed oil content in Arabidopsis

Despite a good understanding of genes involved in oil biosynthesis in seed, the mechanism(s) that controls oil accumulation is still not known. To identify genes that control oil accumulation in seed, we have developed a simple screening method to isolate Arabidopsis seed oil mutants. The method includes an initial screen for seed density followed by a seed oil screen using an automated Nuclear Magnetic Resonance (NMR). Using this method, we isolated ten low oil mutants and one high oil mutant. The high oil mutant, p777, accumulated 8% more oil in seed than did wild type, but it showed no differences in seed size, plant growth or development. The high-oil phenotype is caused by the disruption of the GLABRA2 gene, a previously identified gene that encodes a homeobox protein required for normal trichome and root hair development. Knockout of GLABRA2 did not affect LEAFY COTYLEDON 1 and PICKLE expression in developing embryo. The result indicates that in addition to its known function in trichome and root hair development, GLABRA2 is involved in the control of seed oil accumulation.