Mosses are known to have the ability to develop high degrees of resistance to desiccation and freezing stress at cellular levels. However, underlying cellular mechanisms leading to the development of stress resistance in mosses are not understood. We previously showed that freezing tolerance in protonema cells of the moss Physcomitrella patens was rapidly increased by exogenous application of the stress hormone abscisic acid (ABA) [Minami, A., Nagao, M., Arakawa, K., Fujikawa, S., Takezawa, D., 2003a. Abscisic acid-induced freezing tolerance in the moss Physcomitrella patens is accompanied by increased expression of stress-related genes. J. Plant Physiol. 160, 475-483]. Herein it is shown that protonema cells with acquired freezing tolerance specifically accumulate low-molecular-weight soluble sugars. Analysis of the most abundant trisaccharide revealed that the cells accumulated theanderose (G6-alpha-glucosyl sucrose) in close association with enhancement of freezing tolerance by ABA treatment. The accumulation of theanderose was inhibited by cycloheximide, an inhibitor of nuclear-encoded protein synthesis, coinciding with a remarkable decrease in freezing tolerance. Furthermore, theanderose accumulation was promoted by cold acclimation and treatment with hyperosmotic solutes, both of which had been shown to enhance cellular freezing tolerance. These results reveal a novel role for theanderose, whose biological function has been obscure, in high freezing tolerance in moss cells.

中文翻译：

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在苔藓 Physcomitrella patens 中，红藻糖的积累与耐寒性的发展有关

众所周知，苔藓具有在细胞水平上对干燥和冷冻应激产生高度抗性的能力。然而，导致苔藓抗逆性发展的潜在细胞机制尚不清楚。我们之前表明，外源性应用应激激素脱落酸 (ABA) [Minami, A., Nagao, M., Arakawa, K., Fujikawa, S.,竹泽 D.，2003a。脱落酸诱导的苔藓 Physcomitrella patens 的抗冻性伴随着应激相关基因的表达增加。J. 植物生理学。160, 475-483]。此处显示具有获得性冷冻耐受性的原丝体细胞特异性地积累低分子量可溶性糖。对最丰富的三糖的分析表明，细胞积累了红甘露糖（G6-α-葡萄糖基蔗糖），这与 ABA 处理对冷冻耐受性的增强密切相关。放线菌酮（一种核编码蛋白合成的抑制剂）抑制了红藻糖的积累，同时也显着降低了抗冻性。此外，冷驯化和高渗溶质处理促进了红豆蔻的积累，这两种方法均已显示出增强细胞冷冻耐受性。这些结果揭示了在苔藓细胞的高抗冻性中，其生物学功能一直不明确的红花菊糖的新作用。放线菌酮（一种核编码蛋白合成的抑制剂）抑制了红藻糖的积累，同时也显着降低了抗冻性。此外，冷驯化和高渗溶质处理促进了红豆蔻的积累，这两种方法均已显示出增强细胞冷冻耐受性。这些结果揭示了在苔藓细胞的高抗冻性中，其生物学功能一直不明确的红花菊糖的新作用。放线菌酮（一种核编码蛋白合成的抑制剂）抑制了红藻糖的积累，同时也显着降低了抗冻性。此外，冷驯化和高渗溶质处理促进了红豆蔻的积累，这两种方法均已显示出增强细胞冷冻耐受性。这些结果揭示了在苔藓细胞的高抗冻性中，其生物学功能一直不明确的红花菊糖的新作用。