Characterization and Ectopic Expression of CoWRI1, an AP2/EREBP Domain-Containing Transcription Factor from Coconut (Cocos nucifera L.) Endosperm, Changes the Seeds Oil Content in Transgenic Arabidopsis thaliana and Rice (Oryza sativa L.)

Abstract

Coconut (Cocos nucifera L.) is a key tropical crop and a member of the monocotyledonous family Arecaceae (Palmaceae). Few genes and related metabolic processes involved in coconut endosperm development have been investigated. In this study, a new member of the WRI1 gene family was isolated from coconut endosperm and was named CoWRI1. Its transcriptional activities and interactions with the acetyl-CoA carboxylase (BCCP2) promoter of CoWRI1 were confirmed by the yeast two-hybrid and yeast one-hybrid approaches, respectively. Functional characterization was carried out through seed-specific expression in Arabidopsis and endosperm-specific expression in rice. In transgenic Arabidopsis, high over-expressions of CoWRI1 in seven independent T2 lines were detected by quantitative real-time PCR. The relative mRNA accumulation of genes encoding enzymes involved in either fatty acid biosynthesis or triacylglycerols assembly (BCCP2, KASI, MAT, ENR, FATA, and GPDH) were also assayed in mature seeds. Furthermore, lipid and fatty acids C16:0 and C18:0 significantly increased. In two homozygous T2 transgenic rice lines (G5 and G2), different CoWRI1 expression levels were detected, but no CoWRI1 transcripts were detected in the wild type. Analyses of the seed oil content, starch content, and total protein content indicated that the two T2 transgenic lines showed a significant increase (P < 0.05) in seed oil content. The transgenic lines also showed a significant increase in starch content, whereas total protein content decreased significantly. Further analysis of the fatty acid composition revealed that palmitic acid (C16:0) and linolenic acid (C18:3) increased significantly in the seeds of the transgenic rice lines, but oleic acid (C18:1) levels significantly declined.

Ectopic expression of EuWRI1, encoding a transcription factor in E. ulmoides, changes the seeds oil content in transgenic tobacco

“…Our result suggested that the expression of EuWRI1 might be seed‐specific in E. ulmoides . This result was agreed with previous report that CoWRI1 was highly expressed in endosperm, whereas its expression was lower in other plant tissues . The expression pattern of EuWRI1 in different seed developmental stages with the treatment of GA3 or PAC was also studied in this study.…”

“…8,38 The CoWRI1 overexpression effect on fatty acid content in transgenic A. thaliana seeds significantly differed from the effect in transgenic rice seeds. 17 These results suggested that the transcriptional effects of WRI1 might depend on the origin of the transgene and the transgene recipient as well as the position effect of transgene integration into the host genome.…”

“…This result was agreed with previous report that CoWRI1 was highly expressed in endosperm, whereas its expression was lower in other plant tissues. 17 The expression pattern of EuWRI1 in different seed developmental stages with the treatment of GA3 or PAC was also studied in this study. The result indicated that application of GA3 significantly suppressed EuWRI1 transcript levels in E. ulmoides; however, the exogenous PAC application enhanced EuWRI1 gene expression in seeds of E. ulmoides ( Figure 4A).…”

“…), cotton ( Gossypium spp. ), poplar ( Populus trichocarpa L.), nutsedge ( Cyperus esculentus L.), camelina ( Camelina sativa L.), coconut ( Cocos nucifera L.), and potato ( Solanum tuberosum L.) . Overexpression of the WRI1 gene elevated the transcript level of its target genes involving in fatty acid synthesis and contributed to increased TAG levels in the seeds and vegetative tissues.…”

Unraveling lipid metabolism in maize with time‐resolved multi‐omics data

“…If conserved, knowledge about lipid pathways can be transferred between plant species. The oil content in the seeds of A. thaliana mutants lacking WRINKLED1 ( WRI1 ), a key master regulator of FA biosynthesis in higher plants, was restored with the respective orthologs from rapeseed (Liu et al ., ), Camelina sativa L. (An et al ., ), maize (Pouvreau et al ., ), oil palm (Ma et al ., ) and coconut (Sun et al ., ). In maize, WRI1a and WRI1b encode transcription factors of the APETALA2/ethylene‐responsive element‐binding (AP2/EREB) family that increase FA content in seeds and are co‐expressed with glycolytic enzymes and genes involved in FA and TAG biosynthesis in the kernel (Pouvreau et al ., ).…”