Lipid metabolites in seeds of diverse Gossypium accessions: molecular identification of a high oleic mutant allele

Abstract

Genetically diverse cottonseeds show altered compositions and spatial distributions of phosphatidylcholines and triacylglycerols. Lipidomics profiling led to the discovery of a novel FAD2 - 1 allele, fad2 - 1D - 1 , resulting in a high oleic phenotype. The domestication and breeding of cotton for elite, high-fiber cultivars have led to reduced variation of seed constituents within currently cultivated upland cotton genotypes. However, a recent screen of the genetically diverse U.S. National Cotton Germplasm Collection identified Gossypium accessions with marked differences in seed oil and protein content. Here, several of these accessions representing substantial variation in seed oil content were analyzed for quantitative and spatial differences in lipid compositions by mass spectrometric approaches. Results indicate considerable variation in amount and spatial distribution of pathway metabolites for triacylglycerol biosynthesis in embryos across Gossypium accessions, suggesting that this variation might be exploited by breeders for seed composition traits. By way of example, these lipid metabolite differences led to the identification of a mutant allele of the D-subgenome homolog of the delta-12 desaturase (fad2-1D-1) in a wild accession of G. barbadense that has a high oil and high oleic seed phenotype. This mutation is a 90-bp insertion in the 3' end of the FAD2-1D coding sequence and a modification of the 3' end of the gene beyond the coding sequence leading to the introduction of a premature stop codon. Given the large amounts of cottonseed produced around the world that is currently not processed into higher value products, these efforts might be one avenue to raise the overall value of the cotton crop for producers.

The genome of jojoba ( Simmondsia chinensis ): A taxonomically isolated species that directs wax ester accumulation in its seeds

“…Application of tissue-specific RNA-seq and matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has previously revealed heterogeneous distributions of lipid meta bolites and gene transcripts involved in lipid metabolism across different seed tissues, reflecting an underappreciated spatial regulation to oilseed lipid metabolism (21,(38)(39)(40)(41)(42)(43)(44)(45). Here, jojoba seeds were demonstrated to compartmentalize WEs and express genes involved in storage lipid synthesis in a tissue-specific manner.…”

Registration of four upland cotton germplasm lines with elevated levels of seed oil oleic acid

“…Sequencing of the GB713 genome revealed a divergent allele of the fatty acid desaturase 2-1d gene (fad2-1d) having an 89-bp insertion near the 3 ′ end of the coding sequence, which appears to contribute to the trait (Shockey et al, 2017). The same allele was also identified in GB331, another accession found to exhibit relatively high levels of oleic acid (Sturtevant et al, 2017).…”

“…Crude genomic DNA samples were treated with RNAase A to reduce RNA contamination, then purified using Clean and Concentrate spin columns (Zymo Research). Each sample was tested for the presence of the different FAD2-1D gene alleles by PCR, using combinations of oligonucleotide primers similar to those described by Sturtevant et al (2017). A common forward primer (GbFAD-F, 5 ′ -AGAGTGCCTTTACGT-3 ′ ) was paired with reverse primers specific to either GB713 (GbFAD-Gb713-R, 5 ′ -CCAATTTGTTGCGGAAAGG-3 ′ ) or SG747 (GbFAD-Gh747-R2, 5 ′ -CCAGCGTAAAGTTGAAAATATT-3 ′ ) and amplified using ExTaq HotStart polymerase (TakaraBio).…”

Spatial and Temporal Mapping of Key Lipid Species in Brassica napus Seeds

“…Moreover, observing the spatial context of lipid distribution gives new insights into how associated metabolic networks might be differentially regulated between different tissue types. MALDI-MSI has been used previously with great success to show the spatial heterogeneity of lipid distribution in various plant seeds, such as cotton (Gossypium hirsutum; Horn et al, 2012;Sturtevant et al, 2017b), maize (Zea mays; Feenstra et al, 2015), camelina (Camelina sativa; , and Arabidopsis (Sturtevant et al, 2016(Sturtevant et al, , 2017a, all of which show a certain degree of tissue-specific lipid accumulation across several different lipid classes.…”