Abstract
The seed oil of meadowfoam, a new crop in the Limnanthaceae family, is highly enriched in very long chain fatty acids that are desaturated at the Δ5 position. The unusual oil is desirable for cosmetics and innovative industrial applications and the seed meal remaining after oil extraction contains glucolimnanthin, a methoxylated benzylglucosinolate whose degradation products are herbicidal and anti-microbial. Here we describe EST analysis of the developing seed transcriptome that identified major genes involved in biosynthesis and assembly of the seed oil and in glucosinolate metabolic pathways. mRNAs encoding acyl-CoA Δ5 desaturase were notably abundant. The library was searched for simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). Fifty-four new SSR markers and eight candidate gene markers were developed and combined with previously developed SSRs to construct a new genetic map for Limnanthes alba. Mapped genes in the lipid biosynthetic pathway encode 3-ketoacyl-CoA synthase (KCS), Δ5 desaturase (Δ5DS), lysophosphatidylacyl-acyl transferase (LPAT), and acyl-CoA diacylglycerol acyl transferase (DGAT). Mapped genes in glucosinolate biosynthetic and degradation pathways encode CYP79A, myrosinase (TGG), and epithiospecifier modifier protein (ESM). The resources developed in this study will further the domestication and improvement of meadowfoam as an oilseed crop.
Highlights
Meadowfoam (Limnanthes sp.) is an herbaceous winter annual native to the West Coast of North America (Mason, 1952)
Construction and annotation of a developing embryo cDNA library To identify genes important for meadowfoam seed phenotypes, a cDNA library was made from developing embryos of L.alba subsp. alba excised from their seed coats 14–22 days after fertilization (DAF)
Embryos were collected from 20 plants of cultivar ‘Ross,’ a heterogeneous, open-pollinated population undergoing recurrent selection for desirable agronomic traits (Knapp, Crane & Brunick, 2005). mRNA was isolated from a heterogeneous population to capture sequence variation that could be utilized for DNA-based markers
Summary
Meadowfoam (Limnanthes sp.) is an herbaceous winter annual native to the West Coast of North America (Mason, 1952). Unusual plant fatty acids (FAs) are widespread. How to cite this article Slabaugh et al (2015), Genes affecting novel seed constituents in Limnanthes alba Benth: transcriptome analysis of developing embryos and a new genetic map of meadowfoam. Many of these have potential nutritional uses or novel commercial and industrial uses as renewable sources of raw materials. The synthesis of unusual FAs is restricted to developing seed tissues and they accumulate, often to high levels, in seed storage lipid as triacylglycerol (TAG) (Napier, 2007)
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