| There are a large areas in northern China, and some of farmland have no crop in winter,so it has great potential to plant winter oilseed rape in these areas, but safe overwintering forwinter oilseed rape is a key limiting factor. Because of the good cold resistance in B.rapa, ithas important economic and ecological benefits to develop winter oilseed rape in the cold anddrought areas.The experiment were carried out with4different cold resistance winter rapeseedcultivars, namely2high cold resistance cultivars(Longyou6and Longyou7) and2low coldresistance cultivars(Tianyou2and Tianyou4). The morphological and physi-biochemicalchanges of leaf and root were measured during their natural wintering stage; what’s more,fuzzy mathematics method was used for comprehensive value, which intended to provide atheoretical and technical guidance for identification and cultivation of Brassica campestris L.Besides, based on F2population(Longyou6×Tianyou4), molecular markers was used toscreen cold-related molecular markers, which would be helpful to positioning cold-relatedgenes and molecular marker-assisted breeding of Brassica campestris L.Changes of physiological parameters of4Brassica campestris L.cultivars at winteringstage（5℃→0℃→-5℃→0℃→5℃）:(1) Super anti winter Brassica campestris L.(Longyou6and Longyou7) had a slowershoot growth, faster underground growth and more dry matter accumulation before winteringstage, whose leaves, leaf length and leaf area were less than2other cultivars(Tianyou2andTianyou4) while root length, root diameter, ground and below-ground wet and dry weightwere significantly more than Tianyou2and Tianyou4.(2) During wintering stage, relative conductivity showed the trend of from increasing todecreasing, reaching its peak at-5℃. Therelative conductivity of Tianyou2and Tianyou4were higher than Longyou6and Longyou7during whole wintering stage; The values weresignificant at-5℃, which intended that it was proper temperature to accurately evaluate itscold resistance.(3) During wintering stage, MDA content showed the trend of from increasing todecreasing, reaching its peak at-5℃. TheMDA content of Longyou6and Longyou7werelower than Tianyou2and Tianyou4during whole wintering stage; MDA content in leaf were higher than that in root.(4) During wintering stage, MDA content showed the trend of from increasing todecreasing, POD activity in leaf were lower than that in root at the same temperature. Beforewinter stage at5℃, POD activity in both leaf and root of Tianyou2and Tianyou4werehigher than that in Longyou6and Longyou7, while as the temperature changed, PODactivity in leaf of Longyou6and Longyou7were significant higher than that in Tianyou2and Tianyou4. The CAT of Tianyou2and Tianyou4were higher than Longyou6andLongyou7during whole wintering stage, CAT activity in leaf activity was always higherthan that of the root. In the early winter of5℃-5℃, all the materials showed a trend offirst increasing and then decreasing.(5) The comprehensive value of Longyou6and Longyou7was significantly higher thanTianyou2and Tianyou4, which indicated that the cold resistance of Longyou6andLongyou7were higher than2other cultivars(Tianyou2and Tianyou4).(6) The freezing indexes of F2population(Longyou6×Tianyou4), namely136singleplant, was57.54, the percentage of freezing plant was89.7％。The relative conductivity andMDA content of F2population showed normal distribution.The correlation between molecular markers and physiological indexes:Based on F2population(Longyou6×Tianyou4),504pairs of SSR primers and144pairs of AFLP primers were used to detect the parents, there were47pairs of SSR primersand97pairs of AFLP primers showed difference between them, and the polymorphism rateswere9%and67.4%respectively. Using these primers to screen F2population, the resultsshowed that there were42pairs of SSR primers and94pairs of AFLP primer could showpolymorphism in F2populations with48and162sites respectively.(1) Correlation between SSR markers and physiological indexes:11SSR markers showed significant correlation(P＜0.05) or higher significantcorrelation(P＜0.01) with relative conductivity and MDA content in F2population. Na10-C03,BrGMS4511R and BrGMS397F were higher significant correlation with above2indexes.(2) Correlation between AFLP markers and physiological indexes:6AFLP markers showed significant correlation(P＜0.05) or higher significantcorrelation(P＜0.01) with relative conductivity and MDA content in F2population. Besides,11AFLP markers showed significant correlation with relative conductivity and9AFLPmarkers showed significant correlation with MDA content. |
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