This paper describes the isolation of wheat mutants in the hard red spring Scarlet resulting in reduced sensitivity to the plant hormone abscisic acid (ABA) during seed germination. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature seeds. Wheat sensitivity to ABA gradually decreases with dry after-ripening. Scarlet grain normally fails to germinate when fully dormant, shows ABA sensitive germination when partially after-ripened, and becomes ABA insensitive when after-ripened for 8–12 months. Scarlet ABA-insensitive (ScABI) mutants were isolated based on the ability to germinate on 5 μM ABA after only 3 weeks of after-ripening, a condition under which Scarlet would fail to germinate. Six independent seed-specific mutants were recovered. ScABI1, ScABI2, ScABI3 and ScABI4 are able to germinate more efficiently than Scarlet at up to 25 μM ABA. The two strongest ABA insensitive lines, ScABI3 and ScABI4, both proved to be partly dominant suggesting that they result from gain-of-function mutations. The ScABI1, ScABI2, ScABI3, ScABI4, and ScABI5 mutants after-ripen more rapidly than Scarlet. Thus, ABA insensitivity is associated with decreased grain dormancy in Scarlet wheat. This suggests that ABA sensitivity is an important factor controlling grain dormancy in wheat, a trait that impacts seedling emergence and pre-harvest sprouting resistance.

中文翻译：

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小麦 ABA 不敏感突变体导致谷物休眠减少

本文描述了硬红春猩红色小麦突变体的分离，导致种子萌发过程中对植物激素脱落酸 (ABA) 的敏感性降低。ABA 在胚胎成熟过程中诱导种子休眠并抑制成熟种子的萌发。小麦对 ABA 的敏感性随着干后熟而逐渐降低。猩红色籽粒在完全休眠时通常不会发芽，在部分后熟时表现出对 ABA 敏感的发芽，而在后熟 8-12 个月时则变为对 ABA 不敏感。猩红 ABA 不敏感 (ScABI) 突变体是基于在后熟仅 3 周后在 5 μM ABA 上发芽的能力而分离的，在这种情况下，猩红将无法发芽。回收了六个独立的种子特异性突变体。ScABI1, ScABI2, 在高达 25 μM ABA 的情况下，ScABI3 和 ScABI4 能够比 Scarlet 更有效地发芽。两个最强的 ABA 不敏感品系 ScABI3 和 ScABI4 都被证明是部分显性的，表明它们是由功能获得性突变引起的。ScABI1、ScABI2、ScABI3、ScABI4 和 ScABI5 突变体的后熟速度比 Scarlet 快。因此，ABA 不敏感性与 Scarlet 小麦籽粒休眠减少有关。这表明 ABA 敏感性是控制小麦籽粒休眠的重要因素，这是影响幼苗出苗和收获前萌芽抗性的一个性状。和 ScABI5 突变体的后成熟速度比 Scarlet 快。因此，ABA 不敏感性与 Scarlet 小麦籽粒休眠减少有关。这表明 ABA 敏感性是控制小麦籽粒休眠的重要因素，这是影响幼苗出苗和收获前萌芽抗性的一个性状。和 ScABI5 突变体的后成熟速度比 Scarlet 快。因此，ABA 不敏感性与 Scarlet 小麦籽粒休眠减少有关。这表明 ABA 敏感性是控制小麦籽粒休眠的重要因素，这是影响幼苗出苗和收获前萌芽抗性的一个性状。