Bertrand Annick, Bipfubusa Marie, Claessens Annie, Rocher Solen, Castonguay Yves
Quebec Research and Development Centre, Agriculture and Agri-Food Canada, Québec, QC, G1V 2J3, Canada.
Quebec Research and Development Centre, Agriculture and Agri-Food Canada, Québec, QC, G1V 2J3, Canada.
Plant Sci. 2017 Nov;264:122-128. doi: 10.1016/j.plantsci.2017.09.003. Epub 2017 Sep 12.
Cold acclimation proceeds sequentially in response to decreases in photoperiod and temperature. This study aimed at assessing the impact of photoperiod prior to cold acclimation on freezing tolerance and related biochemical and molecular responses in two alfalfa cultivars. The fall dormant cultivar Evolution and semi-dormant cultivar 6010 were grown in growth chambers under different photoperiods (8, 10, 12, 14 or 16h) prior to cold acclimation. Freezing tolerance was evaluated as well as carbohydrate concentrations, levels of transcripts encoding enzymes of carbohydrate metabolism as well as a K-3dehydrin, before and after cold acclimation. The fall dormant cultivar Evolution had a better freezing tolerance than the semi-dormant cultivar 6010. The effect of photoperiod prior to cold acclimation on the level of freezing tolerance differed between the two cultivars: an 8h-photoperiod induced the highest level of freezing tolerance in Evolution and the lowest in 6010. In Evolution, the 8h-induced superior freezing tolerance was associated with higher concentration of raffinose-family oligosaccharides (RFO). The transcript levels of sucrose synthase (SuSy) decreased whereas those of sucrose phosphatase synthase (SPS) and galactinol synthase (GaS) increased in response to cold acclimation in both cultivars. Our results indicate that RFO metabolism could be involved in short photoperiod-induced freezing tolerance in dormant alfalfa cultivars.
冷驯化是根据光周期和温度的降低依次进行的。本研究旨在评估冷驯化前光周期对两个苜蓿品种抗冻性及相关生化和分子反应的影响。在冷驯化之前，将秋眠品种Evolution和半秋眠品种6010置于不同光周期（8、10、12、14或16小时）的生长室中培养。评估了冷驯化前后的抗冻性、碳水化合物浓度、编码碳水化合物代谢酶的转录本水平以及一种K-3脱水素。秋眠品种Evolution的抗冻性比半秋眠品种6010更好。冷驯化前光周期对两个品种抗冻性水平的影响不同：8小时光周期诱导Evolution达到最高抗冻水平，而在6010中则最低。在Evolution中，8小时诱导的较高抗冻性与棉子糖家族寡糖（RFO）的较高浓度有关。在两个品种中，蔗糖合酶（SuSy）的转录本水平下降，而蔗糖磷酸合酶（SPS）和肌醇半乳糖苷合酶（GaS）的转录本水平在冷驯化后升高。我们的结果表明，RFO代谢可能参与了短光周期诱导的休眠苜蓿品种的抗冻性。
