Abstract
Earliness of flowering and maturity are important traits in spring Brassica napus canola–whether grown under long- or short-day condition. By use of a spring B. napus mapping population carrying the genome content of B. oleracea and testing this population under 10 to 18 h photoperiod and 18 to 20 0C (day) temperature conditions, we identified a major QTL on the chromosome C1 affecting flowering time without being influenced by photoperiod and temperature, and a major QTL on C9 affecting flowering time under a short photoperiod (10 h); in both cases, the QTL alleles reducing the number of days to flowering in B. napus were introgressed from the late flowering species B. oleracea. Additive effect of the C1 QTL allele at 14 to18 h photoperiod was 1.1 to 2.9 days; however, the same QTL allele exerted an additive effect of 6.2 days at 10 h photoperiod. Additive effect of the C9 QTL at 10 h photoperiod was 2.8 days. These two QTL also showed significant interaction in the control of flowering only under a short-day (10 h photoperiod) condition with an effect of 2.3 days. A few additional QTL were also detected on the chromosomes C2 and C8; however, none of these QTL could be detected under all photoperiod and temperature conditions. BLASTn search identified several putative flowering time genes on the chromosomes C1 and C9 and located the physical position of the QTL markers in the Brassica genome; however, only a few of these genes were found within the QTL region. Thus, the molecular markers and the genomic regions identified in this research could potentially be used in breeding for the development of early flowering photoinsensitive B. napus canola cultivars, as well as for identification of candidate genes involved in flowering time variation and photosensitivity.
Highlights
Flowering and maturity are important traits for spring oilseed B. napus for growing this crop in temperate regions, under long-day conditions, as well as in sub-tropical or tropical regions, where the crop is grown during winter under a shorter day [1, 2]
The objective of this research was to understand the genetic control of earliness of flowering and photosensitivity in the C genome of B. napus carrying the genome content introgressed from B. oleracea
Significant correlation was found between the replications (Table B in S1 File); this indicates that the doubled haploid (DH) lines behaved for days to flowering under the same growth condition; data from the replications was pooled and LSmeans values were used for QTL mapping
Summary
Flowering and maturity are important traits for spring oilseed B. napus for growing this crop in temperate regions, under long-day conditions, as well as in sub-tropical or tropical regions, where the crop is grown during winter under a shorter day [1, 2]. In North America and Europe, spring canola requires about 4–5 months from seeding to harvest, while in a subtropical zone, such as Australia, it may require up to 6–7 months. Mapping of flowering time in Brassica C genome. RES0008449 (http://www.acidf.ca/) to HR; Alberta Canola Producers Commission (ACPC), Grant# 2011F006R/RES0008449 Com/) to HR; Crop Production Services (CPS), (http://www.cpsagu.ca/) to HR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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