Developmental control of Arabidopsis seed oil biosynthesis

Abstract

Arabidopsis transcriptional factors LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON2 (LEC2), FUSCA3 (FUS3), ABSCISIC ACID3 (ABI3), and ABSCISIC ACID5 (ABI5) are known to regulate multiple aspects of seed development. In an attempt to understand the developmental control of storage product accumulation, we observed the expression time course of the five transcripts. The sequential expression of these factors during seed fill suggests differentiation of their normal responsibilities. By extending the expression periods of the two early genes LEC1 and LEC2 in transgenic seeds, we demonstrated that the subsequent timing of FUS3, ABI3, and ABI5 transcripts depends on LEC1 and LEC2. Because a delayed onset or reduced level of FUS3 mRNA coincided with reduction of seed oil content in the transgenic seeds, the role of FUS3 in oil deposition was further examined. Analysis of published seed transcriptome data indicated that FUS3 transcript increased together with nearly all the plastidial fatty acid biosynthetic transcripts during development. The ability of FUS3 to rapidly induce fatty acid biosynthetic gene expression was confirmed using transgenic Arabidopsis seedlings expressing a dexamethasone (DEX)-inducible FUS3 and Arabidopsis mesophyll protoplasts transiently expressing the FUS3 gene. By accommodating the current evidence, we propose a hierarchical architecture of the transcriptional network in Arabidopsis seeds in which the oil biosynthetic pathway is integrated through the master transcriptional factor FUS3.

Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds

“…Unfortunately, overexpression of these genes causes a pleiotropic phenotype and even a lethal phenotype, largely owing to that these genes also play a critical role in embryogenesis and seed maturation (Lotan et al, 1998;Stone et al, 2001;Kwong et al, 2003;Cernac and Benning, 2004;Wang et al, 2007;Mu et al, 2008;Shen et al, 2010). This detrimental effect renders it impractical for the use of these genes in molecular breeding by conventional overexpression.…”

“…Overexpression of these genes results in an increased level of FAs in the transgenic Arabidopsis plants, accompanied by up-regulated expression of key FA synthetic genes as well as glycolytic genes (Stone et al, 2001;Kwong et al, 2003;Cernac and Benning, 2004;Baud et al, 2007;Mu et al, 2008). However, in most, if not all cases, overexpression of these transcription factor genes causes a variety of developmental abnormalities and even lethality (Lotan et al, 1998;Stone et al, 2001;Cernac and Benning, 2004;Wang et al, 2007;Mu et al, 2008;Shen et al, 2010). These detrimental effects render it difficult to directly utilize these genes in genetic improvement of oil-producing crops.…”

Global Identification of Targets of theArabidopsisMADS Domain Protein AGAMOUS-Like15

“…The minority of embryo-defective genes encode key regulators of embryogenesis that are expressed primarily or specifically during embryo development and when ectopically expressed are sufficient to drive embryogenic programs in somatic cells. These include the LEAFY COTYLE-DON (LEC) genes that have also been shown to be necessary for somatic embryogenesis (Lotan et al, 1998;Stone et al, 2001;Gazzarrini et al, 2004;Gaj et al, 2005;Wang et al, 2007).…”

Phosphoproteomic Analysis of Seed Maturation in Arabidopsis, Rapeseed, and Soybean

“…The fatty acid composition of Arabidopsis seed is also influenced by a casein kinase I through the phosphorylation of transcription factors for the microsomal oleic acid desaturase (fad2) gene (Kim et al, 2010). The receptor-like kinases, somatic embryogenesis receptor-like kinases, and Crinkly4 have also been determined to be involved in seed development, although their substrate clients have yet to be elucidated (Wang et al, 2007).…”