Molecular basis of the low linolenic acid trait in soybean EMS mutant line RG10

Abstract

A possible solution to stability problems is to genetically reduce the content of linolenic acid in soybean seed. RG10 is a low linolenic acid line (<25 g/kg) produced by ethyl methane sulfonate (EMS) treatment of the low linolenic acid EMS mutant line C1640. The objective of this study was to determine the molecular basis of the low linolenic acid trait in RG10. Sequence analyses of mutant RG10 and wild-type OX948 x-fatty acid desaturase (Fad3) genes showed that the low level of linolenic acid in RG10 is likely a result of mutations in two Fad3 genes. A mutation in the Fad3A gene introduces a stop codon in exon 6 that would prematurely terminate translation and a second mutation in the 5¢ splice site of intron 5 of the Fad3B gene may result in abnormal mRNA splicing products. Both mutations would result in a non-functional enzyme. Molecular markers developed for these mutations should simplify and accelerate introgression of the RG10-based low linolenic acid trait into elite soybean cultivars.

Soybean Oil-Quality Variants Identified by Large-Scale Mutagenesis

“…Mutants with low linolenate (designated fan) have been identified previously, and two independent low linolenic mutants have been shown to contain lesions in the FAD3A gene [5,10,31,32]. When all three FAD3 homologs are downregulated with RNAi in seeds, International Journal of Agronomy linolenic acid levels can be further reduced, therefore, it is possible that mutation in FAD3B or FAD3C may also result in low levels of linolenic acid [33].…”

Identificação de SNPs para conteúdo de ácidos graxos em soja pela técnica HRM

“…Além desses, selecionaram-se, também, os genes FAD3B e FAD3C, que codificam as ω-3-dessaturases e afetam o acúmulo de ácido linolênico em grãos de soja (Bilyeu et al, 2006;Pinto et al, 2013), para os quais já foram desenvolvidos marcadores SNPs (Bilyeu et al, 2006). Portanto, no presente trabalho, testou-se a efetividade da metodologia HRM para a genotipagem desses SNPs, nas populações: A29 x Tucunaré e FA22 x CD219RR, uma vez que seu uso é promissor para a seleção de genótipos superiores de soja (Bilyeu et al, 2005(Bilyeu et al, , 2006(Bilyeu et al, , 2011Reinprecht et al, 2009;Pinto et al, 2013).…”

A Versatile Soybean Recombinant Inbred Line Population Segregating for Low Linolenic Acid and Lipoxygenase Nulls - Molecular Characterization and Utility for Soymilk and Bioproduct Production

“…In order to determine the molecular bases of the LLA and 3lx traits, four ω-3 fatty acid desaturases (Fad3A, Fad3B, Fad3C and Fad3D) and three LX genes (Lx1, Lx2 and Lx3) were sequenced in RG10 and OX948. The mutations in Fad3A gene (same as C1640) and the first characterized mutation in Fad3B gene, make RG10 an attractive source of the LLA trait (Reinprecht et al, 2009). A potential immediate use of RG10 (or its derivatives) is to produce very low LA content soybeans by crossing with lines containing the fan mutation only.…”

“…The initial EMS treatment of the cultivar Century (approximately 70 g kg -1 of linolenic acid) produced line C1640 (Wilcox et al, 1984) with the mutation at the Fad3A ω-3 fatty acid deasturase gene (Chappel & Bilyeu, 2006) resulting in about 50% reduction of LA content (34 g kg -1 ). Further reduction of LA (approximately 30%) to less then 25 g kg -1 , was achieved by mutating the Fad3B gene of C1640 by the EMS treatment to produce RG10 (Reinprecht et al, 2009). Therefore, RG10 has the first mutation in the Fad3A gene [same as C1640, fan(C1640) allele] and the second mutation in the Fad3B gene (fan-b allele).…”

“…Several markers were developed for ω-3 fatty acid desaturase alleles leading to low levels of LA (Reinprecht et al, 2009) and three seed LX nulls in soybean seed . These markers are useful to distinguish between the presence and absence of seed LX (LX1 + LX2 and LX3) as well between the high and low LA levels in a wide range of Ontario soybean germplasm.…”