Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N5A8, Canada.
Plant Mol Biol. 2010 May;73(1-2):49-65. doi: 10.1007/s11103-010-9610-y. Epub 2010 Feb 27.
The role of temperature during dormancy development is being reconsidered as more research emerges demonstrating that temperature can significantly influence growth cessation and dormancy development in woody plants. However, there are seemingly contradictory responses to warm and low temperature in the literature. This research/review paper aims to address this contradiction. The impact of temperature was examined in four poplar clones and two dogwood ecotypes with contrasting dormancy induction patterns. Under short day (SD) conditions, warm night temperature (WT) strongly accelerated timing of growth cessation leading to greater dormancy development and cold hardiness in poplar hybrids. In contrast, under long day (LD) conditions, low night temperature (LT) can completely bypass the short photoperiod requirement in northern but not southern dogwood ecotypes. These findings are in fact consistent with the literature in which both coniferous and deciduous woody plant species' growth cessation, bud set or dormancy induction are accelerated by temperature. The contradictions are addressed when photoperiod and ecotypes are taken into account in which the combination of either SD/WT (northern and southern ecotypes) or LD/LT (northern ecotypes only) are separated. Photoperiod insensitive types are driven to growth cessation by LT. Also consistent is the importance of night temperature in regulating these warm and cool temperature responses. However, the physiological basis for these temperature effects remain unclear. Changes in water content, binding and mobility are factors known to be associated with dormancy induction in woody plants. These were measured using non-destructive magnetic resonance micro-imaging (MRMI) in specific regions within lateral buds of poplar under SD/WT dormancing inducing conditions. Under SD/WT, dormancy was associated with restrictions in inter- or intracellular water movement between plant cells that reduces water mobility during dormancy development. Northern ecotypes of dogwood may be more tolerant to photoinhibition under the dormancy inducing LD/LT conditions compared to southern ecotypes. In this paper, we propose the existence of two separate, but temporally connected processes that contribute to dormancy development in some deciduous woody plant: one driven by photoperiod and influenced by moderate temperatures; the other driven by abiotic stresses, such as low temperature in combination with long photoperiods. The molecular changes corresponding to these two related but distinct responses to temperature during dormancy development in woody plants remains an investigative challenge.
休眠发育过程中的温度作用正受到重新审视，因为越来越多的研究表明，温度会显著影响木本植物的生长停止和休眠发育。然而，文献中对温暖和低温的反应似乎存在矛盾。本研究/综述旨在解决这一矛盾。该研究考察了四个杨树无性系和两个具有不同休眠诱导模式的山茱萸生态型在温度影响下的表现。在短日照（SD）条件下，温暖的夜间温度（WT）强烈加速了生长停止的时间，导致杨树杂种休眠发育和抗寒性增强。相比之下，在长日照（LD）条件下，低温（LT）可以完全绕过北方但不是南方山茱萸生态型的短日照要求。这些发现与文献中的结果一致，即针叶树和落叶木本植物的生长停止、芽形成或休眠诱导都可以通过温度加速。当考虑光周期和生态型时，这些矛盾就会得到解决，其中北方和南方生态型的 SD/WT（或北方生态型的 LD/LT）组合是分开的。对光周期不敏感的类型会被 LT 驱动进入生长停止。夜间温度在调节这些温暖和凉爽温度响应方面的重要性也保持一致。然而，这些温度效应的生理基础仍不清楚。水分含量、结合和流动性的变化是与木本植物休眠诱导相关的已知因素。在 SD/WT 休眠诱导条件下，使用非破坏性磁共振微成像（MRMI）在杨树侧芽的特定区域测量了这些因素。在 SD/WT 下，休眠与植物细胞间或细胞内水分运动的限制有关，这会降低休眠发育过程中的水分流动性。与南方生态型相比，北方山茱萸生态型在休眠诱导的 LD/LT 条件下可能对光抑制更耐受。在本文中，我们提出了两种独立但在时间上相互关联的过程的存在，它们有助于一些落叶木本植物的休眠发育：一种由光周期驱动，受中等温度影响；另一种由非生物胁迫驱动，如低温与长光照相结合。在木本植物休眠发育过程中，对应于这两种与温度相关但明显不同的反应的分子变化仍然是一个具有挑战性的研究课题。
