The LONELY GUY gene family: from mosses to wheat, the key to the formation of active cytokinins in plants

第一作者：Lei Chen

第一单位：烟台大学

第一通讯：Paula E. Jameson

 Abstarct 

背景回顾：LONELY GUY (LOG) was first identified in a screen of rice mutants with defects in meristem maintenance. In plants, LOG codes for cytokinin riboside 5'-monophosphate phosphoribohydrolases, which convert inactive cytokinin nucleotides directly to the active free bases. Many enzymes with the PGGxGTxxE motif have been misannotated as lysine decarboxylases, conversely not all enzymes containing this motif are cytokinin-specific LOGs. 

LOG是通过筛选具有分生组织维持缺陷水稻突变株的方法第一次被鉴定到的。在植物中，LOG基因编码细胞分裂素核苷5'-单磷酸盐磷酸核糖水解酶，作用于将不具生物活性的细胞分裂素核苷直接转化为具生物活性的游离碱基。许多具有PGGxGTxxE基序的酶被错误注释成赖氨酸脱羧酶，反过来说，即并非所有具有该基序的酶都是细胞分裂素特异性LOGs。

主要研究：As LOG mutants clearly impact yield in rice, we investigated the LOG gene family in bread wheat. 

由于水稻中的LOG突变体会表现出明显的产量缺陷，因此作者研究了面包小麦中的LOG基因家族。

结果1-TaLOGs鉴定：By interrogating the wheat (Triticum aestivum) genome database, we show that wheat has multiple LOGs. The close alignment of TaLOG1, 2, and 6 with the X-ray structures of two functional Arabidopsis thaliana LOGs allows us to infer that the wheat LOGs 1-11 are functional LOGs. 

通过检索普通小麦的基因数据库，作者发现小麦中具有多个LOG基因。根据TaLOG1、TaLOG2和TaLOG6与两个拟南芥LOGs蛋白X射线结构的紧密配对，作者推测小麦中TaLOG1-11都是功能性的LOGs。

结果2-组织表达模式：Using RNA-seq data sets, we assessed TaLOG expression across 70 tissue types, their responses to various stressors, the pattern of cis-regulatory elements (CREs), and intron/exon patterns. TaLOG gene family members are expressed variously across tissue types. 

利用RNA-seq数据集，作者评估了TaLOG在70个不同组织类型中的表达情况、对于不同胁迫的响应情况、顺式调控元件的模式以及内含子/外显子模式。TaLOG基因家族的成员在不同的组织类型中具有不同的表达模式。

结果3-CK内稳态机制：When the TaLOG CREs are compared with those of the cytokinin dehydrogenases (CKX) and glucosyltransferases (CGT), there is close alignment of CREs between TaLOGs and TaCKXs reflecting the key role of CKX in maintaining cytokinin homeostasis. 

与细胞分裂素脱氢酶（CKX）和细胞分裂素糖基转移酶（CGT）的顺式作用元件相比，TaLOG的顺式作用元件与TaCKXs的更加匹配，说明了CKX在维持细胞分裂素稳态中发挥重要作用。

结果4-胁迫下的CK内稳态机制：However, we suggest that the main homeostatic mechanism controlling cytokinin levels in response to biotic and abiotic challenge resides in the CGTs, rather than LOG or CKX. 

但是，作者认为在响应生物和非生物胁迫时，控制植物体内细胞分裂素水平的内稳态平衡机制主要还是在于CGTs，而非LOG或CKX。

结论： However, LOG transgenics and identified mutants in rice variously impact yield, providing interesting avenues for investigation in wheat.

但是，水稻中的LOG转基因和突变体均会对产量有不同程度的影响，这为将来小麦的产量研究提供了可能的方向。

** Paula E. Jameson **

doi: https://doi.org/10.1111/pbi.13783

Journal: Plant Biotechnology Journal​

Published date: February 02, 2022