Heterotic patterns in rapeseed (Brassica napus L.): I. Crosses between spring and Chinese semi-winter lines

Abstract

Chinese semi-winter rapeseed is genetically diverse from Canadian and European spring rapeseed. This study was conducted to evaluate the potential of semi-winter rapeseed for spring rapeseed hybrid breeding, to assess the genetic effects involved, and to estimate the correlation of parental genetic distance (GD) with hybrid performance, heterosis, general combining ability (GCA) and specific combining ability (SCA) in crosses between spring and semi-winter rapeseed lines. Four spring male sterile lines from Germany and Canada as testers were crossed with 13 Chinese semi-winter rapeseed lines to develop 52 hybrids, which were evaluated together with their parents and commercial hybrids for seed yield and oil content in three sets of field trials with 8 environments in Canada and Europe. The Chinese parental lines were not adapted to local environmental conditions as demonstrated by poor seed yields per se. However, the hybrids between the Chinese parents and the adapted spring rapeseed lines exhibited high heterosis for seed yield. The average mid-parent heterosis was 15% and ca. 50% of the hybrids were superior to the respective hybrid control across three sets of field trials. Additive gene effects mainly contributed to hybrid performance since the mean squares of GCA were higher as compared to SCA. The correlation between parental GD and hybrid performance and heterosis was found to be low whereas the correlation between GCA((f + m)) and hybrid performance was high and significant in each set of field trials, with an average of r = 0.87 for seed yield and r = 0.89 for oil content, indicating that hybrid performance can be predicted by GCA((f + m)). These results demonstrate that Chinese semi-winter rapeseed germplasm has a great potential to increase seed yield in spring rapeseed hybrid breeding programs in Canada and Europe.

Nitrogen use efficiency in rapeseed. A review

“…Introgression between the comparatively diverse genetic pools of winter, semiwinter, and spring forms, however, may make it possible to exploit heterosis. For instance, Qian et al (2007) showed high heterosis for seed yield in hybrids between Chinese semiwinter pollinators and spring-type mother lines from Europe and Canada. Improvement of spring-type B. napus through the introgression of winter-type variability was also assessed by Kebede et al (2010), who demonstrated the heterosis effect of spring × winter doubled haploid lines over their parental lines.…”

“…Improvement of spring-type B. napus through the introgression of winter-type variability was also assessed by Kebede et al (2010), who demonstrated the heterosis effect of spring × winter doubled haploid lines over their parental lines. To avoid incompatibilities in developmental timing between these potential heterotic groups, Qian et al (2007) suggested that the genetic material should first be adapted to the local environment before being hybridized. It should be noted that the genetic distance between heterotic groups, commonly used to determine the hybridization scheme, is often not correlated with the hybrids' performance.…”

“…Replacing subgenomes in new-type B. napus varieties by introgression from related Brassica species (Udall et al 2004;Qian et al 2007) represents another possibility for widening the global genetic diversity of B. napus by creating new allelic combinations and new intersubgenomic heterosis effects. For instance, NUE diversity of new-type B. napus doubled haploid lines resulting from interspecific crosses between spring B. napus lines, B. rapa, and B. carinata, along with traditional lines of B. napus, were tested under two N regimes by Wang et al (2014).…”

Patterns of Heterosis in Three Distinct Inbred Populations of Spring Brassica napus Canola

“…Quijada et al (2006) identified quantitative trait locus (QTL) alleles of winter cultivars that increase seed yield in spring B. napus test hybrids. Qian et al (2007Qian et al ( , 2009 suggested that some of the alleles in Chinese semi-winter type, likely introgressed from B. rapa L., might contribute to high levels of heterosis for seed yield in both spring and winter B. napus hybrids.…”

“…Thus, most of the studies conducted to date to evaluate different gene pools of Brassica for the improvement of spring or winter or semi-winter B. napus were focused on either the use of spring B. napus for spring type hybrid (Grant and Beversdorf, 1985;Brandle and McVetty, 1990;Engqvist and Becker, 1991;Diers et al, 1996;Cuthbert et al, 2009), or the use of winter or semi-winter B. napus for spring type hybrid (Butruille et al, 1999;Udall et al, 2004;Quijada et al, 2004Quijada et al, , 2006Qian et al, 2007;Kramer et al, 2009), or the use of winter or semi-winter B. napus for winter type hybrid (Lefort-Buson et al, 1987;Qian et al, 2009), or the use of the allied species for winter or semiwinter (Gehringer et al, 2007;Radoev et al, 2008;Zou et al, 2010;Fu et al, 2012;Girke et al, 2012;Li et al, 2014) or spring Seyis et al, 2006) type of hybrid. However, so far, no study has been conducted to compare the value of different gene pools for increasing the level of heterosis and seed yield in spring B. napus hybrid canola.…”