Genetic control of yield and yield components in winter oilseed rape (Brassica napus L.) grown under nitrogen limitation

Abstract

Despite its high nitrogen absorption capacity, oilseed rape (OSR) has a low apparent nitrogen use efficiency (NUE), which makes its production highly dependent on nitrogen fertilization. Improving NUE in OSR is therefore a main target in breeding. The objectives of the present work were to determine the genomic regions (QTLs) associated with yield and to assess their stability under contrasted nitrogen nutrition regimes. One mapping population, AM, was tested in a French location for three growing seasons (2011, 2012 and 2013), under two nitrogen conditions (optimal and low). Eight yield-related traits were scored and nitrogen-responsive traits were calculated. A total of 104 QTLs were detected of which 28 controlled flowering time and 76 were related to yield and yield components. Very few genotype 9 nitrogen interactions were detected and the QTLs were highly stable between the nitrogen conditions. In contrast, only a few QTLs were stable across the years of the trial, suggesting a strong QTL 9 year interaction. Finally, eleven critical genomic regions that were stable across nitrogen conditions and/or trial years were identified. One particular region located on the A5 linkage group appears to be a promising candidate for marker assisted selection programs. The different strategies for OSR breeding using the QTLs found in the present study are discussed.

Nitrogen use efficiency in rapeseed. A review

“…In rapeseed, this interaction is particularly relevant in relation to the negative correlation between oil and protein content of the seeds (Bouchet et al 2014;Stahl et al 2015). Because the main breeding objective is oil yield, both of these traits have to be considered in breeding programs because the protein component represents the major N sink.…”

“…In rapeseed, studies reporting interactions between genotypes and the N nutrition regime (G × N) remain scarce. Miro (2010) found significant quantitative trait locus (QTL) × N interactions for most yieldrelated and NUE-related traits, whereas Gül et al (2002) and Bouchet et al (2014) found relatively consistent control of yield by QTLs between different N nutrition conditions. In addition, the QTL values detected in Miro (2010) and Bouchet et al (2014) varied between the different trials, demonstrating a strong effect of other environmental factors on Nefficiency loci.…”

“…Miro (2010) found significant quantitative trait locus (QTL) × N interactions for most yieldrelated and NUE-related traits, whereas Gül et al (2002) and Bouchet et al (2014) found relatively consistent control of yield by QTLs between different N nutrition conditions. In addition, the QTL values detected in Miro (2010) and Bouchet et al (2014) varied between the different trials, demonstrating a strong effect of other environmental factors on Nefficiency loci. In fact, direct selection appears to be a convenient strategy for NUE breeding in rapeseed (Kessel et al 2012), an observation that has also been reported for wheat (Brancourt-Hulmel et al 2005).…”

“…Such information represents a first step toward the identification of candidate genes, although fine mapping is complicated in rapeseed by the highly complex genome, the long generation time, and the low recombination rates. Some genetic analyses have investigated the genetic control of yieldrelated traits under N stress per se (Gül 2002;Miro 2010;Bouchet et al 2014), but to date, we are aware of no studies that describe the B. napus genome regions associated with NUE-related traits.…”

Development of a breeding strategy for nitrogen use efficiency in spinach (Spinacia oleracea L.)

“…Many studies on genetic variation for NUE in various crops reported large interactions between genotype and N stress and other environmental conditions (Cabrera-Bosquet et al 2007, Anbessa et al 2009, Beatty et al 2010, Wei et al 2012, Chen et al 2013). The investigations of Bouchet et al (2014), using an oilseed rape mapping population are a good example of such studies in which they determined genomic regions (Quantitative Trait Loci (QTLs)) associated with yield and assessed their stability under contrasting nitrogen nutrition regimes. They found many QTLs related to yield and yield components that were stable across N conditions within trial years but not across trial years.…”