Subburaj Saminathan, Luo Nana, Lu Xiaobing, Li Xiaohui, Cao Hui, Hu Yingkao, Li Jiarui, Yan Yueming
College of Life Science, Capital Normal University, Beijing, 100048, China.
Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA.
J Appl Genet. 2016 Aug;57(3):287-303. doi: 10.1007/s13353-015-0316-3. Epub 2015 Oct 30.
Farinins are one of the oldest members of the gluten family in wheat and Aegilops species, and they influence dough properties. Here, we performed the first detailed molecular genetic study on farinin genes in Brachypodium distachyon L., the model species for Triticum aestivum. A total of 51 b-type farinin genes were cloned and characterized, including 27 functional and 24 non-functional pseudogenes from 14 different B. distachyon accessions. All genes were highly similar to those previously reported from wheat and Aegilops species. The identification of deduced amino acid sequences showed that b-type farinins across Triticeae genomes could be classified as b1-, b2-, b3-, and b4-type farinins; however, B. distachyon had only b3- and b4-type farinins. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) revealed that farinin genes are transcribed into mRNA in B. distachyon at much lower levels than in Triticeae, despite the presence of cis-acting elements in promoter regions. Phylogenetic analysis suggested that Brachypodium farinins may have closer relationships with common wheat and further confirmed four different types of b-type farinins in Triticeae and Brachypodium genomes, corresponding to b1, b2, b3 (group 1), and b4 (group 2). A putative evolutionary origin model of farinin genes in Brachypodium, Triticum, and the related species suggests that all b-type farinins diverged from their common ancestor ~3.2 million years ago (MYA). The b3 and b4 types could be considered older in the farinin family. The results explain the loss of b1- and b2-type farinin alleles in Brachypodium.
醇溶蛋白是小麦和山羊草属物种中面筋家族最古老的成员之一，它们会影响面团特性。在此，我们对小麦的模式物种二穗短柄草中的醇溶蛋白基因进行了首次详细的分子遗传学研究。总共克隆并鉴定了51个b型醇溶蛋白基因，包括来自14个不同二穗短柄草种质的27个功能基因和24个无功能的假基因。所有基因都与先前从小麦和山羊草属物种中报道的基因高度相似。推导氨基酸序列的鉴定表明，小麦族基因组中的b型醇溶蛋白可分为b1-、b2-、b3-和b4型醇溶蛋白；然而，二穗短柄草只有b3-和b4型醇溶蛋白。实时定量逆转录聚合酶链反应（qRT-PCR）显示，尽管启动子区域存在顺式作用元件，但二穗短柄草中醇溶蛋白基因转录成mRNA的水平远低于小麦族。系统发育分析表明，短柄草醇溶蛋白可能与普通小麦有更密切的关系，并进一步证实了小麦族和短柄草基因组中存在四种不同类型的b型醇溶蛋白，分别对应b1、b2、b3（第1组）和b4（第2组）。一个关于短柄草、小麦及相关物种中醇溶蛋白基因的推测进化起源模型表明，所有b型醇溶蛋白在约320万年前（百万年前）从它们的共同祖先分化而来。b3和b4类型在醇溶蛋白家族中可能被认为更古老。这些结果解释了二穗短柄草中b1-和b2型醇溶蛋白等位基因的丢失。
