Martínez-Barajas Eleazar, Delatte Thierry, Schluepmann Henriette, de Jong Gerhardus J, Somsen Govert W, Nunes Cátia, Primavesi Lucia F, Coello Patricia, Mitchell Rowan A C, Paul Matthew J
Plant Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, United Kingdom.
Plant Physiol. 2011 May;156(1):373-81. doi: 10.1104/pp.111.174524. Epub 2011 Mar 14.
Trehalose 6-phosphate (T6P) is a sugar signal that regulates metabolism, growth, and development and inhibits the central regulatory SNF1-related protein kinase1 (SnRK1; AKIN10/AKIN11). To better understand the mechanism in wheat (Triticum aestivum) grain, we analyze T6P content and SnRK1 activities. T6P levels changed 178-fold 1 to 45 d after anthesis (DAA), correlating with sucrose content. T6P ranged from 78 nmol g(-1) fresh weight (FW) pregrain filling, around 100-fold higher than previously reported in plants, to 0.4 nmol g(-1) FW during the desiccation stage. In contrast, maximum SnRK1 activity changed only 3-fold but was inhibited strongly by T6P in vitro. To assess SnRK1 activity in vivo, homologs of SnRK1 marker genes in the wheat transcriptome were identified using Wheat Estimated Transcript Server. SnRK1-induced and -repressed marker genes were expressed differently pregrain filling compared to grain filling consistent with changes in T6P. To investigate this further maternal and filial tissues were compared pre- (7 DAA) and during grain filling (17 DAA). Strikingly, in vitro SnRK1 activity was similar in all tissues in contrast to large changes in tissue distribution of T6P. At 7 DAA T6P was 49 to 119 nmol g(-1) FW in filial and maternal tissues sufficient to inhibit SnRK1; at 17 DAA T6P accumulation was almost exclusively endospermal (43 nmol g(-1) FW) with 0.6 to 0.8 nmol T6P g(-1) FW in embryo and pericarp. The data show a correlation between T6P and sucrose overall that belies a marked effect of tissue type and developmental stage on T6P content, consistent with tissue-specific regulation of SnRK1 by T6P in wheat grain.
海藻糖-6-磷酸（T6P）是一种糖信号，可调节代谢、生长和发育，并抑制核心调节因子SNF1相关蛋白激酶1（SnRK1；AKIN10/AKIN11）。为了更好地了解小麦（Triticum aestivum）籽粒中的机制，我们分析了T6P含量和SnRK1活性。开花后1至45天（DAA），T6P水平变化了178倍，与蔗糖含量相关。T6P在籽粒灌浆前的鲜重（FW）中为78 nmol g⁻¹，比之前报道的植物中的含量高约100倍，在干燥阶段降至0.4 nmol g⁻¹ FW。相比之下，最大SnRK1活性仅变化了3倍，但在体外被T6P强烈抑制。为了评估体内SnRK1活性，使用小麦估计转录本服务器在小麦转录组中鉴定了SnRK1标记基因的同源物。与籽粒灌浆期相比，SnRK1诱导和抑制的标记基因在籽粒灌浆前的表达不同，这与T6P的变化一致。为了进一步研究这一点，比较了孕穗期（7 DAA）和籽粒灌浆期（17 DAA）的母体和子代组织。令人惊讶的是，与T6P组织分布的巨大变化形成对比的是，体外SnRK1活性在所有组织中相似。在7 DAA时，子代和母体组织中的T6P为49至119 nmol g⁻¹ FW，足以抑制SnRK1；在17 DAA时，T6P几乎完全积累在胚乳中（43 nmol g⁻¹ FW），胚和果皮中的T6P为0.6至0.8 nmol g⁻¹ FW。数据表明T6P与蔗糖总体上存在相关性，但掩盖了组织类型和发育阶段对T6P含量的显著影响，这与T6P在小麦籽粒中对SnRK1的组织特异性调节一致。
