Graduate School of Science & Engineering, Saitama University, Saitama, Japan.
Physiol Plant. 2023 Jan;175(1):e13837. doi: 10.1111/ppl.13837.
Plants adapt to freezing stress through cold acclimation, which is induced by nonfreezing low temperatures and accompanied by growth arrest. A later increase in temperature after cold acclimation leads to rapid loss of freezing tolerance and growth resumption, a process called deacclimation. Appropriate regulation of the trade-off between freezing tolerance and growth is necessary for efficient plant development in a changing environment. The cell wall, which mainly consists of polysaccharide polymers, is involved in both freezing tolerance and growth. Still, it is unclear how the balance between freezing tolerance and growth is affected during cold acclimation and deacclimation by the changes in cell wall structure and what role is played by its monosaccharide composition. Therefore, to elucidate the regulatory mechanisms controlling freezing tolerance and growth during cold acclimation and deacclimation, we investigated cell wall changes in detail by sequential fractionation and monosaccharide composition analysis in the model plant Arabidopsis thaliana, for which a plethora of information and mutant lines are available. We found that arabinogalactan proteins and pectic galactan changed in close coordination with changes in freezing tolerance and growth during cold acclimation and deacclimation. On the other hand, arabinan and xyloglucan did not return to nonacclimation levels after deacclimation but stabilized at cold acclimation levels. This indicates that deacclimation does not completely restore cell wall composition to the nonacclimated state but rather changes it to a specific novel composition that is probably a consequence of the loss of freezing tolerance and provides conditions for growth resumption.
植物通过低温驯化适应冰冻胁迫,低温驯化是由非冻结低温诱导的,并伴随着生长停滞。低温驯化后温度的升高会导致快速丧失抗冻能力和恢复生长,这个过程称为脱驯化。在不断变化的环境中,为了实现植物的高效发育,需要适当调节抗冻能力和生长之间的权衡。细胞壁主要由多糖聚合物组成,参与抗冻能力和生长。然而,细胞壁结构的变化如何影响低温驯化和脱驯化过程中抗冻能力和生长之间的平衡,以及其单糖组成扮演什么角色,目前还不清楚。因此,为了阐明控制低温驯化和脱驯化过程中抗冻能力和生长的调节机制,我们通过顺序分级分离和单糖组成分析,在模式植物拟南芥中详细研究了细胞壁的变化,因为拟南芥有大量的信息和突变体株系可用。我们发现,在低温驯化和脱驯化过程中,阿拉伯半乳糖蛋白和果胶半乳糖与抗冻能力和生长的变化密切协调。另一方面,脱驯化后阿拉伯聚糖和木葡聚糖没有恢复到非驯化水平,而是稳定在低温驯化水平。这表明脱驯化不会将细胞壁组成完全恢复到非驯化状态,而是将其改变为特定的新组成,这可能是抗冻能力丧失的结果,并为恢复生长提供了条件。