Plant Biology Unit, Gembloux Agro-Bio Tech, Liège University, 2 A avenue de la Faculté d'agronomie, 5030 Gembloux, Belgium.
J Plant Physiol. 2010 Apr 15;167(6):497-501. doi: 10.1016/j.jplph.2009.10.014. Epub 2009 Dec 11.
Grain protein content (GPC) is a key quality factor for malting and brewing process. In wheat, a QTL explaining a large part of GPC variation was identified, which co-localizes with a gene encoding a NAC transcription factor (TtNAM-B1). NAC transcription factors influence GPC by their role in the regulation of senescence and in protein remobilization. An orthologous gene was discovered on barley chromosome 6H where a GPC QTL was mapped. In this study, we identify allelic variation of the NAM-1 gene for three species of Hordeum representing wild and cultivated barley and we investigate the possible link with GPC. Three haplotypes were identified, one corresponds to the sequences of 11 European varieties representing H. vulgare, one corresponds to the sequence found in H. spontaneum and one represents the sequence of H. bulbosum. Three SNPs were identified between H. spontaneum sequence and H. vulgare sequence. One of the H. bulbosum polymorphisms leads to the introduction of a stop codon and a non-functional protein. Differences in GPC between the 11 varieties were found but no polymorphism in the NAM-1 gene was observed, suggesting that differences in expression of the HvNAM-1 gene or other genes should play a role in GPC regulation. Nevertheless based on published values for GPC of H. bulbosum and H. spontaneum compared to GPC measured here in H. vulgare, the non-functional protein is associated with the lower GPC, suggesting that loss of functionality of the NAM-1 gene in Hordeum is related to lower GPC. Moreover H. spontaneum GPC seems to be higher than H. vulgare GPC, suggesting also that allelic variation of the functional NAM-1 gene could be associated with GPC variation within the genus Hordeum.
谷物蛋白质含量（Grain protein content，GPC）是麦芽和酿造过程的关键质量因素。在小麦中，已鉴定出一个解释 GPC 大部分变异的 QTL，该 QTL 与编码 NAC 转录因子（TtNAM-B1）的基因共定位。NAC 转录因子通过在衰老和蛋白质再动员中的作用影响 GPC。在大麦 6H 染色体上发现了一个与 GPC QTL 定位的同源基因。在这项研究中，我们鉴定了代表野生和栽培大麦的三个大麦属种的 NAM-1 基因的等位变异，并研究了与 GPC 的可能联系。鉴定出三种单倍型，一种与代表 H. vulgare 的 11 个欧洲品种的序列相对应，一种与在 H. spontaneum 中发现的序列相对应，一种代表 H. bulbosum 的序列。在 H. spontaneum 序列和 H. vulgare 序列之间鉴定出三个 SNPs。H. bulbosum 多态性之一导致引入一个终止密码子和一个无功能的蛋白质。在 11 个品种之间发现了 GPC 的差异，但在 NAM-1 基因中没有观察到多态性，这表明 HvNAM-1 基因或其他基因的表达差异可能在 GPC 调节中发挥作用。尽管基于与这里测量的 H. vulgare 相比，H. bulbosum 和 H. spontaneum 的 GPC 公布值，无功能的蛋白质与较低的 GPC 相关，表明 NAM-1 基因在大麦中的功能丧失与较低的 GPC 相关，但 H. spontaneum 的 GPC 似乎高于 H. vulgare 的 GPC，这也表明功能性 NAM-1 基因的等位变异可能与大麦属内的 GPC 变异有关。
