DataSheet_3_The Brittle Rachis Trait in Species Belonging to the Triticeae and Its Controlling Genes Btr1 and Btr2.fasta

In many non-cultivated angiosperm species, seed dispersal is facilitated by the shattering of the seed head at maturity; in the Triticeae tribe, to which several of the world's most important cereals belong, shattering takes the form of a disarticulation of the rachis. The products of the genes Btr1 and Btr2 are both required for disarticulation to occur above the rachis nodes within the genera Hordeum (barley) and Triticum/Aegilops (wheat). Here, it has been shown that both Btr1 and Btr2 are specific to the Triticeae tribe, although likely paralogs (Btr1-like and Btr2-like) are carried by the family Poaceae including Triticeae. Aegilops tauschii (the donor of the bread wheat D genome) lacks a copy of Btr1 and disarticulation in this species occurs below, rather than above the rachis node; thus, the product of Btr1 appears to be required for disarticulation to occur above the rachis node.

在诸多非栽培被子植物物种中，种子传播依赖于成熟时穗部的自然开裂脱落；在全球多数重要谷类作物所属的小麦族（Triticeae）中，该脱落过程表现为穗轴的节间断离。在大麦属（Hordeum，即大麦）以及小麦属/山羊草属（Triticum/Aegilops，即小麦）的类群中，Btr1与Btr2基因的编码产物均为穗轴节上方发生断离所必需。本研究证实，Btr1与Btr2均为小麦族所特有，尽管禾本科（Poaceae，包含小麦族）的基因组中普遍存在其疑似旁系同源基因（Btr1-like与Btr2-like）。节节麦（Aegilops tauschii，普通小麦D基因组的供体）缺失Btr1基因拷贝，其穗部断离发生于穗轴节下方而非上方；由此可见，Btr1的编码产物是穗轴节上方发生断离的必要条件。