Expression of GhWRI1 Increases Seed Mass and Oil Content in Arabidopsis

WRINKLED1 (WRI1) is an APETALA2 (AP2)-type specific transcription factor with two AP2 DNA-binding domains which involved in many developmental processes in plant, including in seed development. Here, a homolog GhWRI1 was isolated from upland cotton (Gossypium hirsutum L.) by using RT-PCR and RACE strategy. GhWRI1 had the transcriptional activation and the transcription activation domain was located in the C-terminal of the protein with yeast one-hybrid. The expression patterns of GhWRI1 in five Gossypium species contain different seed oil content indicated that GhWRI1 participated in the process of oil accumulation in cotton seed. GhWRI1 was over expressed driven by cauliflower mosaic virus 35S promoter in Arabidopsis thaliana and 29 homozygous transgenic lines were obtained. Gas chromatography (GC) analysis on seeds from transgenic lines showed that most of transgenic seeds had 5% more oil contents than those wild seeds of Col-0 type. Over-expression of GhWRI1 could increase the seed sizes and weights obviously in several transgenic lines, and the changes were due to increasing the embryo cell sizes of seeds investigated under the scanning electron microscope (SEM). Furthermore, the expression level of enoyl-ACP reductase (EAR), pyruvate kinases (PKp2), and acetyl CoA carboxylase (ACCase) BCCP2 subunit, which played important role in de novo fatty acid synthesis and had been reported were the downstream targets of AtWRI1, were significantly induced in homozygous transgenic lines by qRT-PCR. These results showed that GhWRI1 gene has potential applications in modification of seed oil content and enlarged seed size and seed mass in cotton plants.