<i>Wrinkled</i> 1 (WRI1) Homologs, AP2-Type Transcription Factors Involving Master Regulation of Seed Storage Oil Synthesis in Castor Bean (<i>Ricinus communis</i>L.)

Abstract

Among APETALA2 (AP2)-type plant specific transcription factor family, WRINKLED1 (WRI1), has appeared to be a master gene transcriptionally regulating a set of carbon metabolism-and fatty acid synthesis (FAS)-related genes responsible for seed specific triacylglycerols (TAGs) storage in oil plants. B3 type transcription factors, such as ABI3 and FUS3, are known to be involved in seed development, such as seed storage protein synthesis and maturation. Based on the recent whole genome sequence data of castor bean (Ricinus communis L.), putative WRI1 homologs (RcWRI1, RcWRI2) specifically expressed in castor bean seed have been identified by comparing organ specific expression profiles among seed development-related transcription factors, seed storage specific genes (Ricin, RcOleosin) and a set of FAS genes including genes for sucrose synthase (RcSUS2), biotin carboxyl carrier protein (a subunit of acetyl-CoA carboxylase, RcBCCP2) and ketoacyl-acyl carrier protein synthase (RcKAS1). Immunoreactive signals with WRI1, FUS3 and ABI5-related polypeptides were also detected in seed specifically, consistent with the expression profiles of seed development-related genes. The WRI1 binding consensus sites, [CnTnG](n)(7) [CG], designated as the AW-box, were found at the promoter region of RcBCCP2 and RcKAS1. Thus, RcWRI1 possibly play a pivotal role in seed specific TAGs storage during seed development by directly activating FAS -related genes.

The Mediator Complex MED15 Subunit Mediates Activation of Downstream Lipid-Related Genes by the WRINKLED1 Transcription Factor

“…Consistent with the results of the wri1 mutant, overexpression of WRI1 up-regulated a number of glycolytic and fatty acid biosynthetic genes in seedlings and increased the overall seed oil content without altering its fatty acid composition in Arabidopsis. Similar WRI1 overexpression results have been obtained in oilseed rape (Brassica napus), maize (Zea mays), and castor bean (Ricinus communis; Liu et al, 2010;Pouvreau et al, 2011;Sanjaya et al, 2011;Tajima et al, 2013), indicating functional conservation of WRI1 in both monocots and dicots.…”

Molecular Basis of Plant Oil Biosynthesis: Insights Gained From Studying the WRINKLED1 Transcription Factor

“…A high degree of cross-species conservation is a hallmark of important master transcriptional regulators. A number of WRI1 orthologs have been found in various monocot and dicot plant species, including Brassica napus (Liu et al, 2010), Brachypodium distachyon , Camelina sativa , Zea mays (Shen et al, 2010;Pouvreau et al, 2011), Elaeis guineensis (Bourgis et al, 2011;Ma et al, 2013), Glycine max (Manan et al, 2017;Zhang et al, 2017;Chen et al, 2020), Ricinus communis (Tajima et al, 2013;Ji et al, 2018), Avena sativa (Grimberg et al, 2015), Cocos nucifera , Cyperus esculentus (Grimberg et al, 2015), Gossypium spp (Qu et al, 2012), Jatropha curcas (Ye et al, 2018), Persea americana (Kilaru et al, 2015), Solanum tuberosum (Grimberg et al, 2015), and Oryza sativa (Mano et al, 2019). Expressing AtWRI1 or WRI1 orthologs in wri1 loss-of-function mutants complemented the decreased seed oil phenotype of wri1 (Cernac and Benning, 2004;Pouvreau et al, 2011;Ma et al, 2013;An et al, 2017;Ye et al, 2018;Chen et al, 2020).…”

Response of Castor Bean Plants to Different Row Spacings and Planting Seasons

“…The field was not irrigated. 12 The cultivar BRS Nordestina was sown during two different seasons, October 2007 (first season) and March 2008 (second season). Three seeds per hole were used for subsequent thinning, leaving one plant per hole.…”

“…In determining plant populations, the climate, soil characteristics, the cultivar to be planted and Response of Castor Bean Plants to Different Row Spacings and Planting Seasons 11 the management style to be employed all must be considered [9][10][11][12]. Highly fertile or adequately fertilised soils and water availability conditions can result in the lush growth of castor bean plants, leading to plant lodging and hindering management and harvesting operations and the final yield [11].…”