Abstract
BackgroundThe fatty acid composition of B. napus’ seeds determines the oil’s nutritional and industrial values, and affects seed germination. Many studies have reported correlations among C16:0, C18:0, C18:1, C18:2 and C18:3 based on phenotypic data; however, the genetic basis of the fatty acid composition in B. napus is still not well understood.ResultsIn this study, unconditional and conditional quantitative trail locus (QTL) mapping analyses were conducted using a recombinant inbred line in six environments. In total, 21 consensus QTLs each for C16:0, C18:0 and C18:2, 16 for C18:1 and 22 for C18:3 were detected by unconditional mapping. The QTLs with overlapping confidence intervals were integrated into 71 pleiotropically unique QTLs by meta-analysis. Two major QTLs, uuqA5–6 and uuqA5–7, simultaneously affected the fatty acids, except C18:0, in most of environments, with the homologous genes fatty acid desaturase 2 (FAD2) and glycerol-3-phosphate sn-2-acyltransferase 5 (GPAT5) occurring in the confidence interval of uuqA5–6, while phosphatidic acid phosphohydrolase 1 (PAH1) was assigned to uuqA5–7. Moreover, 49, 30, 48, 60 and 45 consensus QTLs were detected for C16:0, C18:0, C18:1, C18:2 and C18:3, respectively, by the conditional mapping analysis. In total, 128 unique QTLs were subsequently integrated from the 232 conditional consensus QTLs. A comparative analysis revealed that 63 unique QTLs could be identified by both mapping methodologies, and 65 additional unique QTLs were only identified in conditional mapping.ConclusionsThus, conditional QTL mapping for fatty acids may uncover numerous additional QTLs that were inhibited by the effects of other traits. These findings provide useful information for better understanding the genetic relationships among fatty acids at the QTL level.
Highlights
The fatty acid composition of B. napus’ seeds determines the oil’s nutritional and industrial values, and affects seed germination
Conclusions: conditional quantitative trail locus (QTL) mapping for fatty acids may uncover numerous additional QTLs that were inhibited by the effects of other traits
These findings provide useful information for better understanding the genetic relationships among fatty acids at the QTL level
Summary
The fatty acid composition of B. napus’ seeds determines the oil’s nutritional and industrial values, and affects seed germination. The modern rapeseed varieties produce oil with less than 2% erucic acid, 5% to 8% saturated fats (mainly palmitic and stearic acids), 60% to 65% monounsaturated fats (mainly oleic acid) and 30% to 35% polyunsaturated fats (mainly linoleic and linolenic acids) [2]. For the two saturated FA components, the major QTLs for palmitic acid (C16:0) have mostly been identified on linkage groups A8, A10, C1, C4 and C8 in previous studies [3,4,5,6,7]; Chen et al BMC Plant Biology (2018) 18:49 and the major QTLs for stearic acid (C18:0) are generally located on A1, A5, A6, A7, A8 and C3 [3,4,5,6,7]. For the two polyunsaturated fats, the major QTLs for linoleic acid (C18:2) are largely across A5, A8, A9, C3 and C4 [3,4,5,6,7,8,9], and the major QTLs for linolenic acid (C18:3) are mainly distributed on A4, A5, A6, A7, C3 and C4 [3,4,5,6,7,8,9,10]
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