Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
Plant Cell Physiol. 2012 Apr;53(4):606-16. doi: 10.1093/pcp/pcs019. Epub 2012 Feb 25.
Thermospermine is a structural isomer of spermine, which is one of the polyamines studied extensively in the past, and is produced from spermidine by the action of thermospermine synthase encoded by a gene named ACAULIS5 (ACL5) in plants. According to recent genome sequencing analyses, ACL5-like genes are widely distributed throughout the plant kingdom. In Arabidopsis, ACL5 is expressed specifically during xylem formation from procambial cells to differentiating xylem vessels. Loss-of-function mutants of ACL5 display overproliferation of xylem vessels along with severe dwarfism, suggesting that thermospermine plays a role in the repression of xylem differentiation. Studies of suppressor mutants of acl5 that recover the wild-type phenotype in the absence of thermospermine suggest that thermospermine acts on the translation of specific mRNAs containing upstream open reading frames (uORFs). Thermospermine is a novel type of plant growth regulator and may also serve in the control of wood biomass production.
热稳定精胺是精胺的结构异构体，精胺是过去广泛研究的多胺之一，它由植物中命名为 ACAULIS5（ACL5）的基因编码的热稳定精胺合酶作用于精胺产生。根据最近的基因组测序分析，ACL5 样基因在整个植物界广泛分布。在拟南芥中，ACL5 特异性地在韧皮部细胞到分化的木质部导管的木质部形成过程中表达。ACL5 的功能丧失突变体显示木质部导管过度增殖以及严重的矮化，表明热稳定精胺在木质部分化的抑制中发挥作用。对 acl5 的抑制突变体的研究表明，在没有热稳定精胺的情况下，恢复野生型表型，提示热稳定精胺作用于含有上游开放阅读框（uORFs）的特定 mRNA 的翻译。热稳定精胺是一种新型的植物生长调节剂，也可能参与控制木材生物量的产生。
