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A diverse population (429 member) of canola (Brassica napus L.) consisting primarily of winter biotypes was assembled and used in genome-wide association studies. Genotype by sequencing analysis of the population identified and mapped 290,972 high-quality markers ranging from 18.5 to 82.4% missing markers per line and an average of 36.8%. After interpolation, 251,575 high-quality markers remained. After filtering for markers with low minor allele counts (count > 5), we were left with 190,375 markers. The average distance between these markers is 4463 bases with a median of 69 and a range from 1 to 281,248 bases. The heterozygosity among the imputed population ranges from 0.9 to 11.0% with an average of 5.4%. The filtered and imputed dataset was used to determine population structure and kinship, which indicated that the population had minimal structure with the best K value of 2–3. These results also indicated that the majority of the population has substantial sequence from a single population with sub-clusters of, and admixtures with, a very small number of other populations. Analysis of chromosomal linkage disequilibrium decay ranged from ~7 Kb for chromosome A01 to ~68 Kb for chromosome C01. Local linkage decay rates determined for all 500 kb windows with a 10kb sliding step indicated a wide range of linkage disequilibrium decay rates, indicating numerous crossover hotspots within this population, and provide a resource for determining the likely limits of linkage disequilibrium from any given marker in which to identify candidate genes. This population and the resources provided here should serve as helpful tools for investigating genetics in winter canola. [ABSTRACT FROM AUTHOR]

Including winter canola (Brassica napus L.) crop into cereal-based crop rotations can diversify the current agricultural systems in the United States (US). In addition, canola can help to satisfy market demand for plant-based edible oil, thus better understanding of oil productivity of canola in the US production areas is relevant for further study. Canola seed oil concentration is a function of the genotype (G), environment (E), management (M), and their interaction (G × E × M). The overall aim of this research study was to identify suitable production environments with increased canola seed oil concentration and opportunities to increase cropland area in the US. The objectives of this research were: i) characterize the environmental variability of seed oil concentration in the National Winter Canola Variety Trials (NWCVT), ii) identify geographical regions and states within the continental US with potential for production of winter canola with high seed oil concentration and the link with yield, and iii) explore the potential development of varieties with stable high seed oil concentration and high yield. In this study, the E component accounted for 75% of the total variation in seed oil concentration, with the G factor only explaining 8%. Overall, seed oil concentration averaged 398 g kg-1 but ranged from 311 to 461 g kg-1. The US Midwest and Great Plains regions were shown to have a greater frequency of medium (> 389 g kg-1) and high canola seed oil concentration (> 411 g kg-1). Genotypic variation for both seed oil concentration and yield was found with an opportunity to achieve high oil and yield under varying environments. Our findings suggests that there is significant potential to further expand the area of canola cropland to increase oil productivity and focus should be on breeding high yielding varieties with stable high seed oil concentration. • Environment explained most of the oil concentration variability in winter canola. • Precipitation and photothermal quotient explain the oil concentration variability. • Large winter canola production area with potential for high oil concentration in US. • Potential to develop varieties with stable high seed oil concentration and yield. [ABSTRACT FROM AUTHOR]

• Canola winter survival was linked to minimum temperature and its fluctuations • High probability of canola winter survival reported south latitude 35°N in US • There is potential to develop canola genotypes with tolerance to winter-kill • Semi-tolerant canola types for winter survival are already broadly used in US • Canola winter survival response driven by air temperatures and windchill The introduction of winter canola (Brassica napus L.) into rotations with winter wheat (Triticum aestivum L.) in the United States (US) revealed economic and agronomic benefits as well as improved weed and pest control. Canola stand establishment during the fall and plant survival over the winter are critical to the success of this crop. The environment plays a key role influencing survival, but in-depth evaluation of meteorological factors has not been conducted. This research study aimed to: i) identify meteorological factors underpinning winter canola survival, ii) build probabilistic response models based on historical meteorological data for different severities of winter kill across the US, and iii) define areas of adaptation of current germplasm. A winter survival dataset was compiled from the National Winter Canola Variety Trials from 2003 until 2018 (190 site-years) and auxiliary meteorological data over the last 40 years. A regression tree analysis indicated that meteorological variables related to minimum temperature, fluctuating temperatures above and below 0°C, and windchill during the cold period were the main factors accounting for winter kill. Cold periods across all site-years were classified into three clusters: cold periods with high (96%), medium (70%), and low (28%) average plant winter survival. For 94 US sites, the probabilities of these conditions were calculated and summarized in a map that defined areas of adaptation: a large area south of 35° N latitude for the US was identified with greater potential for overwintering success. Based on the response under multiple meteorological conditions, four distinct genotype survival groups were identified (tolerant, semi-tolerant, semi-susceptible, and susceptible). Groups with a greater number of genotypes differ in the impact of meteorological conditions on survival for the medium cluster. In regions with more favorable conditions for overwintering success, farmers may be open to introducing this crop to diversify their farming system. [ABSTRACT FROM AUTHOR]