Freezing triggers extracellular ice formation leading to cell dehydration and deformation during a freeze–thaw cycle. Many plant species increase their freezing tolerance during exposure to low, non‐freezing temperatures, a process termed cold acclimation. In addition, exposure to mild freezing temperatures after cold acclimation evokes a further increase in freezing tolerance (sub‐zero acclimation). Previous transcriptome and proteome analyses indicate that cell wall remodelling may be particularly important for sub‐zero acclimation. In the present study, we used a combination of immunohistochemical, chemical and spectroscopic analyses to characterize the cell walls of Arabidopsis thaliana and characterized a mutant in the XTH19 gene, encoding a xyloglucan endotransglucosylase/hydrolase (XTH). The mutant showed reduced freezing tolerance after both cold and sub‐zero acclimation, compared to the Col‐0 wild type, which was associated with differences in cell wall composition and structure. Most strikingly, immunohistochemistry in combination with 3D reconstruction of centres of rosette indicated that epitopes of the xyloglucan‐specific antibody LM25 were highly abundant in the vasculature of Col‐0 plants after sub‐zero acclimation but absent in the XTH19 mutant. Taken together, our data shed new light on the potential roles of cell wall remodelling for the increased freezing tolerance observed after low temperature acclimation.

中文翻译：

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木葡聚糖内转葡糖基化酶/水解酶XTH19对细胞壁的修饰会影响低温和零度适应后的冷冻耐受性

冻结触发细胞外冰的形成，导致细胞在冻融循环中脱水和变形。许多植物在暴露于低温，非冰冻温度时会提高其耐寒性，这一过程称为冷驯化。此外，冷驯化后暴露于温和的冰冻温度会引起冰冻耐受性的进一步提高（亚零驯化）。先前的转录组和蛋白质组分析表明，细胞壁重塑对于零度以下适应可能特别重要。在本研究中，我们结合了免疫组织化学，化学和光谱学分析来表征拟南芥的细胞壁并鉴定了XTH19中的突变体基因，编码木葡聚糖内转葡糖基酶/水解酶（XTH）。与Col-0野生型相比，该突变体在寒冷和零度适应后显示出降低的抗冻性，这与细胞壁组成和结构的差异有关。最为显着的是，免疫组织化学结合玫瑰花心的3D重建表明，在低于零的适应水平后，木葡聚糖特异性抗体LM25的表位在Col-0植物的脉管系统中高度丰富，但在XTH19突变体中却不存在。两者合计，我们的数据为低温适应后观察到的细胞壁重塑对于提高耐冻性的潜在作用提供了新的启示。