PDF(Pubmed)
Abstract：
Sucrose is the transport form of carbohydrate in plants serving as signal molecule besides nutrition, but the signaling is elusive. Here, neutral invertase 8 (OsNIN8) mutated at G461R into OsNIN8m, which increased its charge and hydrophobicity, decreased hydrolysis of sucrose to 13% and firmer binding to sucrose than the wildtype. This caused downstream metabolites and energy accumulation forming overnutrition. Paradoxically, division of subinitials in longitudinal cell lineages was only about 15 times but more than 100 times in wildtype, resulting in short radicle. Further, mutation of OsNIN8 into deficiency of hydrolysis but maintenance of sucrose binding allowed cell division until ran out of energy showing the association but not hydrolysis gave the signal. Chemically, sucrose binding to OsNIN8 was exothermic but to OsNIN8m was endothermic. Therefore, OsNIN8m lost the signal function owing to change of thermodynamic state. So, OsNIN8 sensed sucrose for cell division besides hydrolyzed sucrose.
摘要：
蔗糖是碳水化合物在植物中的运输形式，除了营养外，还作为信号分子，但是信号难以捉摸。这里,中性转化酶8（OsNIN8）在G461R突变为OsNIN8m，增加了它的电荷和疏水性，与野生型相比，蔗糖的水解降低至13％，并且与蔗糖的结合更牢固。这导致下游代谢物和能量积累形成营养过剩。矛盾的是,纵向细胞谱系的亚首字母的划分在野生型中只有约15倍，但超过100倍，导致短胚根。Further,OsNIN8突变为水解不足，但保持蔗糖结合允许细胞分裂，直到耗尽显示缔合但不水解的能量发出信号。化学上,蔗糖与OsNIN8的结合是放热的,但与OsNIN8m的结合是吸热的。因此,由于热力学状态的变化，OsNIN8m失去了信号功能。所以,除水解蔗糖外，OsNIN8还感应蔗糖用于细胞分裂。
