title: Nonsense-mediated mRNA degradation of CtFAD2-1 and development of a perfect molecular marker for olol mutation in high oleic safflower (Carthamus tinctorius L.).
abstract: There are two types of safflower oil, high oleic (HO) with 70-75 % oleic acid and high linoleic (HL) with about 70 % linoleic acid. The original HO trait in safflower, found in an introduction from India, is controlled by a partially recessive allele ol at a single locus (Knowles and Bill 1964). In the lipid biosynthesis pathway of developing safflower seeds, microsomal oleoyl phosphatidylcholine desaturase (FAD2) is largely responsible for the conversion of oleic acid to linoleic acid. In vitro microsomal assays indicated drastically reduced FAD2 enzyme activity in the HO genotype compared to conventional HL safflower. A previous study indicated that a single-nucleotide deletion was found in the coding region of CtFAD2-1 that causes premature termination of translation in the HO genotypes, and the expression of the mutant CtFAD2-1Δ was attenuated in the HO genotypes compared to conventional HL safflower (Guan et al. 2012). In this study, we hypothesise that down-regulation of CtFAD2-1 expression in the HO genotype may be explained by nonsense-mediated RNA decay (NMD). NMD phenomenon, indicated by gene-specific RNA degradation of defective CtFAD2-1Δ, was subsequently confirmed in Arabidopsis thaliana seed as well as in the transient expression system in Nicotiana benthamiana leaves. We have developed a perfect molecular marker corresponding to the olol mutation that can facilitate a rapid screening and early detection of genotypes carrying the olol mutation for use in marker-assisted selection for the management of the HO trait in safflower breeding programmes.
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, ACT 2601, Australia. qing.liu@csiro.au
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.forename: Shijiang
authors.initials: S
authors.lastname: Cao
authors.forename: Xue-Rong
authors.initials: XR
authors.lastname: Zhou
authors.forename: Craig
authors.initials: C
authors.lastname: Wood
authors.forename: Allan
authors.initials: A
authors.lastname: Green
authors.forename: Surinder
authors.initials: S
authors.lastname: Singh
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D031187:Carthamus tinctorius / Q000201:enzymology / Q000235:genetics*; D015536:Down-Regulation; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005819:Genetic Markers; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D007194:India; D019787:Linoleic Acid / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009154:Mutation; D059365:Nonsense Mediated mRNA Decay / Q000235:genetics*; D019301:Oleic Acid / Q000096:biosynthesis; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012639:Seeds / Q000737:chemistry; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000737:chemistry / Q000235:genetics
chemical_list: D005819:Genetic Markers; D010938:Plant Oils; D010940:Plant Proteins; D019301:Oleic Acid; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; C021904:Phosphatidylcholine desaturase; D044925:Oxidoreductases Acting on CH-CH Group Donors