BnWRI1 coordinates fatty acid biosynthesis and photosynthesis pathways during oil accumulation in rapeseed

Abstract

Photosynthesis in "green" seeds, such as rapeseed, soybean, and Arabidopsis, plays a substantial role in the improved efficiency of oil accumulation. However, the molecular mechanism underpinning the coordinated expression of fatty acid (FA) biosynthesis- and photosynthesis-related genes in such developing seeds remains to be elucidated. Here, we found that seed-specific overexpression of BnWRI1, a WRI1 homolog from rapeseed (Brassica napus cv. ZGY2), results in enhanced chlorophyll content in developing seeds and increased oil content and seed mass in matured seeds. BnWRI1 was co-expressed with BnBCCP and BnCAB, two marker genes of FA biosynthesis and photosynthesis during seed development, respectively. Overexpression of BnWRI1 increased expression of both marker genes. Further, the nuclear-localized BnWRI1 protein was found to act as a transcription activator. It could bind to the GT1-element and/or GCC-box, which are widespread in the upstream regions of genes involved in FA biosynthesis and photosynthesis pathways. Accordingly, BnWRI1 could interact with promoters of BCCP2 and LHB1B2 in vivo. These results suggested that BnWRI1 may coordinate FA biosynthesis and photosynthesis pathways in developing seeds via directly stimulating expression of GT1-element and/or GCC-box containing genes.

Overexpression of Arabidopsis WRI1 enhanced seed mass and storage oil content in Camelina sativa

“…3). Similar results were also obtained in transgenic Arabidopsis and rapeseed overexpressing BnWRI1 (Liu et al 2010;Wu et al 2014). Although the molecular mechanisms underlying the enhanced growth of embryonic cells in the transgenic lines overexpressing WRI1 are still unclear, a higher ratio of sucrose to hexose is known to be related with cell expansion and seed filling at the later stage of seed development (Weber et al 1996(Weber et al , 1997.…”

“…It was observed that the levels of seed oils increased by approximately 10-20 % in T 4 seeds of transgenic Arabidopsis overexpressing AtWRI1 (Cernac and Benning 2004). When rapeseed WRI1 (BnWRI1) was overexpressed in Arabidopsis and rapeseed, the total seed oil contents increased by approximately 20 and 10 %, respectively, and in particular, the size of seed oil bodies was observed to be enlarged in rapeseed overexpressing BnWRI1 (Liu et al 2010;Wu et al 2014). In addition, the overexpression of maize WRI1 (ZmWRI1) caused an increase in the contents of kernel oil in transgenic maize plants by approximately 31 % (Shen et al 2010;Pouvreau et al 2011).…”

“…Later, WRI1 orthologs were isolated from several crops including maize (Zea mays), rapeseed (Brassica napus), palm (Elaeis guineensis), and cotton (Gossypium spp.) (Ma et al 2013;Shen et al 2010;Pouvreau et al 2011;Qu et al 2012;Wu et al 2014). It has been reported that the seed oil contents in transgenic Arabidopsis, rapeseed, and maize overexpressing AtWRI1 or WRI1 orthologs increase by approximately 10-30 % (Cernac and Benning 2004;Liu et al 2010;Shen et al 2010;Wu et al 2014).…”

Multigene Engineering of Triacylglycerol Metabolism Boosts Seed Oil Content in Arabidopsis

“…Arabidopsis is only a model species and has not been subjected to artificial selection for agronomic traits such as seed oil content or yield. However, WRI1 and DGAT1 overexpression have been reported individually to boost seed oil content in maize (Zheng et al, 2008;Shen et al, 2010) and oilseed rape (Brassica napus; Weselake et al, 2008;Wu et al, 2014). Furthermore, suppression of SDP1 can also enhance seed oil content in oilseed rape (Kelly et al, 2013a) and Jatropha curcas (Kim et al, 2014).…”

Camelina, a Swiss knife for plant lipid biotechnology

“…WRINKLED1 (WRI1) was shown to be an essential transcription factor for TAG synthesis in many species, and its overexpression led to 10-30% increase in seed oil content in arabidopsis, rapeseed and even maize (Cernac and Benning, 2004;Baud et al, 2007;Liu et al, 2010;Pouvreau et al, 2011;Wu et al, 2014). Overexpression of arabidopsis AtWRI1 in camelina seeds led to an increase in seed weight and seed size, and as expected, to 8-31% increase in seed oil content (An and Suh, 2015).…”