Splice Variants of the Castor WRI1 Gene Upregulate Fatty Acid and Oil Biosynthesis When Expressed in Tobacco Leaves

• Published in: International journal of molecular sciences 2018-01, Vol.19 (1), p.146
• Main Authors: Ji, Xia-Jie, Mao, Xue, Hao, Qing-Ting, Liu, Bao-Ling, Xue, Jin-Ai, Li, Run-Zhi
• Format: Article
• Language: English
• Subjects: alternative splice form; Alternative Splicing; Biosynthesis; castor (Ricinus communis L.); Castor Oil - biosynthesis; Castor Oil - genetics; fatty acid and oil biosynthesis; Fatty acids; Fatty Acids - biosynthesis; Fatty Acids - genetics; Flowers; Gene expression; Gene Expression Regulation, Plant; Isoforms; Leaves; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana tabacum; Oilseeds; Open reading frames; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; RcWRI1; Ricinus - genetics; Ricinus communis; Seeds; Tobacco; tobacco (Nicotiana benthamiana L.); Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transgenes; Up-Regulation
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms19010146

The plant-specific WRINKLED1 (WRI1) is a member of the AP2/EREBP class of transcription factors that positively regulate oil biosynthesis in plant tissues. Limited information is available for the role of WRI1 in oil biosynthesis in castor bean ( L.), an important industrial oil crop. Here, we report the identification of two alternatively spliced transcripts of , designated as and . The open reading frames of (1341 bp) and (1332 bp) differ by a stretch of 9 bp, such that the predicted RcWRI1-B lacks the three amino acid residues "VYL" that are present in RcWRI1-A. The transcript is present in flowers, leaves, pericarps and developing seeds, while the mRNA is only detectable in developing seeds. When the two isoforms were individually introduced into an loss-of-function mutant, total fatty acid content was almost restored to the wild-type level, and the percentage of the wrinkled seeds was largely reduced in the transgenic lines relative to the mutant line. Transient expression of each splice isoform in leaves upregulated the expression of the WRI1 target genes, and consequently increased the oil content by 4.3-4.9 fold when compared with the controls, and appeared to be more active than . Both and can be used as a key transcriptional regulator to enhance fatty acid and oil biosynthesis in leafy biomass.