Assessment of seed quality performance and heterosis for seed quality traits in hybrid high erucic acid rapeseed (HEAR)

Cuthbert, R. D., Crow, G. and McVetty, P. B. E. 2011. Assessment of seed quality performance and heterosis for seed quality traits in hybrid high erucic acid rapeseed (HEAR). Can. J. Plant Sci. 91: 837–846. Hybrids are becoming the dominant cultivar type in Brassica napus L. to utilize the well-documented heterosis for seed yield in canola/rapeseed. While there are numerous reports of heterosis for agronomic traits in B. napus hybrids, there are few reports of heterosis for seed quality traits in this species. The objectives of this study were to determine if high parent or commercial heterosis for any seed quality traits occurs in high erucic acid rapeseed (HEAR) hybrids. Seed quality performance of 45 F1 B. napus HEAR hybrids, derived from crosses of 12 geographically and genetically distinct (based on known pedigrees) HEAR cultivars/lines, was assessed in the current study using seven HEAR cultivars/lines developed by the University of Manitoba (UM) and five proprietary European (EU) HEAR cultivars/lines. Replicated field trials to assess seed oil, protein, sum of oil and protein, glucosinolate, and erucic acid concentrations were conducted over six environments in Manitoba during 2004 and 2005. High parent heterosis and commercial heterosis for seed oil concentration up to 9% and up to 14%, respectively, was observed with hybrids displaying seed oil concentrations as high as 533 g kg−1. Low parent heterosis for protein and glucosinolate concentrations was also observed. Erucic acid concentration displayed commercial heterosis. Many hybrids displayed near zero percent heterosis for any seed quality traits; however, overall seed quality was maintained or increased even in these hybrids. The results of this study indicate that development of HEAR hybrids can be an effective way to improve seed quality components, especially oil concentration, in this crop.

Assessment of agronomic performance and heterosis for agronomic traits in hybrid high erucic acid rapeseed (HEAR)

Twelve genetically diverse and geographically distinct high erucic acid rapeseed (HEAR) Brassica napus L. cultivars/lines were selected and crossed by hand emasculation in a topcross design to produce 45 F1 hybrid combinations. Seven of the twelve parents were HEAR cultivars/lines developed by the University of Manitoba (UM) and the remaining five parents were proprietary European (EU) HEAR cultivars/lines. Adequate seed was produced to evaluate the hybrids and parents in replicated yield trials in six environments in Manitoba during 2004 and 2005. Vigor, days to first flower, days to maturity, lodging, plant height, and seed yield were assessed. The hybrids were generally more vigorous, taller and more lodging resistant than their parents with similar days to first flower and days to maturity as their earlier parents. The best hybrids in this study displayed high parent heterosis for seed yield of up to 143% and commercial heterosis for seed yield of up to 99%. These hybrids were from the most genetically diverse UM × EU crosses. HEAR hybrids appear very promising approach to increase seed yields in this crop. Key words: Brassica napus L., HEAR, heterosis, hybrids, genetic diversity

Comparison of pedigree selection and doubled haploid breeding methods for high erucic acid rapeseed cultivar development

Sixty families from pedigree selection and 60 lines from doubled haploid development per cross, for three different Brassica napus L. high erucic acid rapeseed (HEAR) crosses, were created and then compared for agronomic and seed quality performance in four environments in Manitoba in 2000 and 2001. Differences in mean performance for many traits were observed within crosses; however, these differences were not consistent among crosses. Similarly, there were differences observed in ranges for many traits within crosses but with few clear trends among crosses. Similar numbers of superior pedigree selection families and doubled haploid lines within and among crosses for individual traits and for combinations of all traits were found in this study. Financial and temporal resource requirements for these two breeding methods were found to be similar. It is concluded that both pedigree selection and doubled haploid breeding methods have their particular strengths and weaknesses but that neither is clearly superior for the development of B. napus HEAR cultivars. Key words: Brassica napus L., HEAR, breeding method comparisons

Enzymic activities and gene expression of enzymes of the acyl-CoA elongase during rapeseed development

Enzymic activities and gene expression of oleoylCoA elongase were studied during seed development using two different rapeseed cultivars, high-erucic-acid rapeseed (HEAR) and low-erucic-acid rapeseed (LEAR). The overall elongase activities were maximal in HEAR between the fourth and eighth weeks after pollination (WAP) and absent in LEAR. The 3-ketoacyl-CoA synthase (condensing enzyme, CE) mRNA levels and the developmental profiles in the two cultivars were different since maximal expression levels were detected in HEAR and LEAR at WAP 4 and WAP 6, respectively. Anti-CE antibodies revealed two proteins of 60 and 67 kDa in both cultivars and an additional reacting protein of 57 kDa in HEAR.