Department of Plant-bioscience, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan.
United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, Potsdam D-14476, Germany.
J Proteomics. 2019 Apr 15;197:71-81. doi: 10.1016/j.jprot.2018.11.008. Epub 2018 Nov 14.
Freezing stress is one of the most important limiting factors of plant survival. Plants have developed a freezing adaptation mechanism upon sensing low temperatures (cold acclimation). Compositional changes in the plasma membrane, one of the initial sites of freezing injury, is prerequisite of achieving cold acclimation and have been investigated in several plant species. Conversely, the cold dehardening process at elevated temperatures (de-acclimation) has not yet been fully characterized and few studies have addressed the importance of the plasma membrane in the de-acclimation process. In the present study, we conducted shotgun proteomics with label-free semiquantification on plasma membrane fractions of Arabidopsis leaves during cold acclimation and de-acclimation. We consequently obtained a list of 873 proteins with significantly changed proteins in response to the two processes. Although the cold-acclimation-responsive proteins were globally returned to non-acclimated levels by de-acclimation, several representative cold-acclimation-responsive proteins tended to remain at higher abundance during de-acclimation process. Taken together, our results suggest plants deharden right after cold acclimation to restart growth and development but some cold-acclimation-induced changes of the plasma membrane may be maintained under de-acclimation to cope with the threat of sudden freezing during de-acclimation process. SIGNIFICANCE: Plant freezing tolerance can be enhanced by low temperature treatment (cold acclimation), while elevated temperatures right after cold acclimation can result in the dehardening of freezing tolerance (de-acclimation). However, the de-acclimation process, particularly its relevance to the plasma membrane as the primary site of freezing injury, has not been elucidated. In the present study, a comprehensive proteomic analysis of the plasma membrane during cold acclimation and de-acclimation was carried out as a first step to elucidating how plants respond to rising temperatures. Cold acclimation induced a number of proteomic changes as reported in previous studies, but most proteins, in general, immediately returned to NA levels during de-acclimation treatment for two days. However, the abundances of stress-related proteins (e.g. LTI29, COR78 and TIL) decreased slower than other functional proteins during de-acclimation. Therefore, plants harden during cold acclimation by aborting growth and development and accumulating stress-responsive proteins but seem to deharden quickly under subsequent elevated temperature to resume these processes while guarding against the threat of sudden temperature drops.
植物在感知低温时会形成抗冻适应机制（冷驯化），抗冻压力是影响植物生存的最重要限制因素之一。在细胞膜等初始冻害部位的组成变化是冷驯化的前提，这在多个植物物种中已有研究。相反，在较高温度下的冷脱驯化过程（脱驯化）尚未完全阐明，很少有研究涉及细胞膜在脱驯化过程中的重要性。在本研究中，我们对拟南芥叶片冷驯化和脱驯化过程中的质膜进行了无标记半定量的鸟枪法蛋白质组学研究。因此，我们获得了一份 873 种蛋白质的列表，这些蛋白质的表达水平在这两个过程中发生了显著变化。虽然脱驯化使冷驯化响应蛋白总体上恢复到非驯化水平，但几种有代表性的冷驯化响应蛋白在脱驯化过程中仍倾向于保持较高的丰度。总之，我们的研究结果表明，植物在冷驯化后立即进行脱驯化以重新开始生长和发育，但在脱驯化过程中，可能会维持一些由冷驯化诱导的质膜变化，以应对脱驯化过程中突然降温的威胁。意义：低温处理（冷驯化）可以增强植物的抗冻性，而冷驯化后温度升高会导致抗冻性脱驯化（脱驯化）。然而，脱驯化过程，特别是其与细胞膜作为冻害初始部位的相关性，尚未阐明。在本研究中，我们首次对冷驯化和脱驯化过程中的质膜进行了全面的蛋白质组学分析，以阐明植物如何应对温度升高。冷驯化诱导了许多蛋白质组学变化，如先前研究报道的那样，但在脱驯化处理的两天内，大多数蛋白质通常立即恢复到非驯化水平。然而，应激相关蛋白（如 LTI29、COR78 和 TIL）的丰度在脱驯化过程中比其他功能蛋白下降得更慢。因此，植物通过停止生长和发育并积累应激响应蛋白来在冷驯化过程中变硬，但在随后的高温下似乎很快脱驯化，以恢复这些过程，同时防止突然降温的威胁。
