青稞是青藏高原极具特色的作物类型。研究青稞早熟性形成的遗传机制

对于揭示青稞对青藏高原极短生育期条件的适应和进化过程具有重要的科学意义。日前，中科院西北高原生物研究所和四川大学合作，在青稞早熟适应性方面取得重要进展，相关成果发布于《理论与应用遗传学》。

科研人员在青海西宁和四川温江两地的表型鉴定结果发现，来自西藏的青稞地方品种“拉鲁青稞”开花时间比晚熟品种“迪青 1 号”早 15-21 天，生育期差异显著。他们通过对来自于这两种早熟与晚熟品种的杂交组合的 279 个 F2 个体的表型分析，认为“拉鲁青稞”的早开花性状由单个隐性基因控制。他们进一步的遗传和物理图谱构建工作将该控制基因定位于 1HL 上并确定其为生物种基因 EAM8 的隐性等位变异。相关序列分析结果表明，“拉鲁青稞”EAM8 第三个内含子中存在的 A / G 替换导致该基因在转录时发生可变剪接和内含子保留，之后提前出现的终止密码子最终导致无功能的截断蛋白的形成，将该等位基因定名为 eam8.l。

科研人员发现的 eam8.l 等位基因是植物中第一个发现的可变剪接导致早熟的自然突变基因。该项研究结果提示可变剪接可能是青稞生物钟基因进化和短生育期适应性形成的重要遗传机制之一，同时在青藏高原其它一年生植物中也可能存在相似的适应性形成机制。（来源：科学网 彭科峰）

The alternative splicing of EAM8 contributes to early flowering and short-season adaptation in a landrace barley from the Qinghai-Tibetan Plateau

Abstract  Barley is a staple crop grown over an extensive area in the Qinghai-Tibetan Plateau. Understanding the genetic mechanism for its success in a high altitude is important for crop improvement in marginal environments. Early flowering is a critical adaptive trait that strongly influences reproductive fitness in a short growing season. Loss-of-function mutations at the circadian clock gene EARLY MATURITY 8 (EAM8) promote rapid flowering. In this study, we identified a novel, spontaneous recessive eam8 mutant with an early flowering phenotype in a Tibetan barley landrace Lalu, which is natively grown at a high altitude of approximately 4000 m asl. The co-segregation analysis in a F2 population derived from the cross Lalu (early flowering) × Diqing 1 (late flowering) confirmed that early flowering of Lalu was determined to be due to an allele at EAM8. The eam8 allele from Lalu carries an A/G alternative splicing mutation at position 3257 in intron 3, designated eam8.l; this alternative splicing event leads to intron retention and a putative truncated protein. Of the 134 sequenced barley accessions, which are primarily native to the Qinghai-Tibet Plateau, three accessions carried this mutation. The eam8.l mutation was likely to have originated in wild barley due to the presence of the Lalu haplotype in H. spontaneum from Tibet. Overall, alternative splicing has contributed to the evolution of the barley circadian clock and in the short-season adaptation of local barley germplasm. The study has also identified a novel donor of early-flowering barley which will be useful for barley improvement.

原文链接：https://link.springer.com/article/10.1007/s00122-016-2848-2