小麦tae-MIR156前体基因的克隆及其靶基因TaSPL17多态性分析

Cloning of tae-MIR156 precursor gene and sequence polymorphisms of tae-miR156 targeted TaSPL17

Squamosa-promoter binding protein(SBP)-box基因是植物特有的一类转录因子,广泛参与植物生长发育,其部分成员受miR156调控。文章克隆了小麦(Triticum aestivum)tae-MIR156前体基因,转录后能够形成茎环结构。小麦10个SBP-box基因中,仅TaSPL3和TaSPL17在编码区存在tae-miR156识别位点。SPL17在普通小麦的A基因组供体种乌拉尔图小麦(Triticum urartu,AA)UR209和B基因组供体种拟斯卑尔脱山羊草(Aegilops speltoides,BB)Y2001中均为多拷贝(SPL17-A1、SPL17-A2和SPL17-A3;SPL17-B1、SPL17-B2和SPL17-B3),在D基因组供体种粗山羊草(Aegilops tauschii,DD)Ae38中仅检测到一种序列(SPL17-D);SPL17-A2与SPL17-B2,SPL17-A3与SPL17-B3、SPL17-D两两之间序列的一致性程度均大于99%,且与普通小麦(中国春、衡观35和双丰收)的TaSPL17序列具有较高的一致性,提示它们可能来源于共同的祖先基因,并且在进化过程中高度保守。靶基因TaSPL17中的tae-miR156识别位点非常保守,在根据单株穗数和基因型多样性挑选的SubP1和SubP2群体中均未检测到tae-miR156识别位点存在变异碱基。

Squamosa-promoter binding protein （SBP）-box genes, encoding plant-specific transcription factors, play an important role in plant development. Some members of the SBP-box gene family are regulated by miR156. In this study, we cloned the tae-MIR156 precursor gene, which could form a stem loop after its transcription. Sequence analysis showed that TaSPL3 and TaSPL17 had putative targets of tae-miR156 among the ten wheat SBP-box genes. The diploid donor species of hexaploid common wheat （Triticum aestivum, genome AABBDD）, i.e., Triticum urartu （AA） UR209 and Aegilops spel-toides Y2001 （SS, closely related to BB） possessed more than one copy of SPL17 （SPL17-A1, SPL17-A2 and SPL17-A3 from Triticum urartu;SPL17-B1, SPL17-B2 and SPL17-B3 from Aegilops speltoides）, while Aegilops tauschii （DD） Ae38 only possessed one （SPL17-D）. The identities between nucleotide sequences of SPL17-A2 and SPL17-B2, SPL17-A3 and SPL17-B3 or SPL17-D were higher than 99%. They were highly similar with the sequence of TaSPL17 in common wheat cultivars Chinese Spring, Hengguan 35 and Shuangfengshou. These genes might originate from a common ancestor and were highly conserved in the process of evolution. The target site of tae-miR156 in TaSPL17 was also highly conserved in two subgroups consisted of accessions with diverse spike number per plant and genetic background.