title: Altered seed oil and glucosinolate levels in transgenic plants overexpressing the Brassica napus SHOOTMERISTEMLESS gene.
abstract: SHOOTMERISTEMLESS (STM) is a homeobox gene conserved among plant species which is required for the formation and maintenance of the shoot meristem by suppressing differentiation and maintaining an undetermined cell fate within the apical pole. To assess further the role of this gene during seed storage accumulation, transgenic Brassica napus (Bn) plants overexpressing or down-regulating BnSTM under the control of the 35S promoter were generated. Overexpression of BnSTM increased seed oil content without affecting the protein and sucrose level. These changes were accompanied by the induction of genes encoding several transcription factors promoting fatty acid (FA) synthesis: LEAFY COTYLEDON1 (BnLEC1), BnLEC2, and WRINKLE1 (BnWRI1). In addition, expression of key representative enzymes involved in sucrose metabolism, glycolysis, and FA biosynthesis was up-regulated in developing seeds ectopically expressing BnSTM. These distinctive expression patterns support the view of an increased carbon flux to the FA biosynthetic pathway in developing transformed seeds. The overexpression of BnSTM also resulted in a desirable reduction of seed glucosinolate (GLS) levels ascribed to a transcriptional repression of key enzymes participating in the GLS biosynthetic pathway, and possibly to the differential utilization of common precursors for GLS and indole-3-acetic acid synthesis. No changes in oil and GLS levels were observed in lines down-regulating BnSTM. Taken together, these findings provide evidence for a novel function for BnSTM in promoting desirable changes in seed oil and GLS levels when overexpressed in B. napus plants, and demonstrate that this gene can be used as a target for genetic improvement of oilseed species.
authors.affiliation: Department of Plant Science, University of Manitoba, Winnipeg, R3T 2N2, Manitoba, Canada.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Elhiti
authors.forename: Cunchun
authors.initials: C
authors.lastname: Yang
authors.forename: Ainsley
authors.initials: A
authors.lastname: Chan
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Durnin
authors.forename: Mark F
authors.initials: MF
authors.lastname: Belmonte
authors.forename: Belay T
authors.initials: BT
authors.lastname: Ayele
authors.forename: Muhammad
authors.initials: M
authors.lastname: Tahir
authors.forename: Claudio
authors.initials: C
authors.lastname: Stasolla
mesh_terms: D000244:Adenosine Diphosphate / Q000032:analysis / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D001692:Biological Transport; D029688:Brassica napus / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D005961:Glucosinolates / Q000032:analysis / Q000378:metabolism*; D006019:Glycolysis; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D010938:Plant Oils / Q000032:analysis / Q000378:metabolism*; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D012639:Seeds / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013395:Sucrose / Q000032:analysis / Q000378:metabolism; D015854:Up-Regulation / Q000235:genetics
chemical_list: D005227:Fatty Acids; D005961:Glucosinolates; D010938:Plant Oils; D010940:Plant Proteins; D013395:Sucrose; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate