Quantifying the sensitivity of barley seed germination to oxygen, abscisic acid, and gibberellin using a population-based threshold model
Quantifying the sensitivity of barley seed germination to oxygen, abscisic acid, and gibberellin using a population-based threshold model
复制标题
DOI：
10.1093/jxb/erm315
复制
发表时间：
2008-02-01
影响因子：
6.9
通讯作者：
Corbineau, Francoise
中科院分区：
文献类型：
--
作者：
Bradford, Kent J.;Benech-Arnold, Roberto L.;Corbineau, Francoise
大麦(Hordeum visgare L.)种子(籽粒)在成熟时表现出休眠，这主要是由于颖壳的存在减少了对胚胎的氧气供应(O-2)。此外，脱落酸(ABA)和赤霉素(GAs)与O-2相互作用调节大麦种子休眠。基于群体的阈值模型被用来量化种子和离体胚对O-2、ABA和GA的敏感性以及它们之间的交互作用。休眠的完整大麦种子萌发所需的氧气中位数是离体胚的400倍，这表明包裹胚芽的组织明显限制了氧气的穿透。然而，胚胎O-2阈值在后成熟后下降了另一个数量级。因此，谷壳对O-2的透性和胚胎对O-2的敏感性的增加有助于提高后熟过程中的萌发能力。ABA和GA对萌发对O-2的敏感性影响相对较小，但ABA和GA的阈值对O-2的响应变化在几个数量级内，对ABA的敏感性随着低氧的增加而增加，对GA的敏感性随着低氧的增加而降低。O-2-ABA和O-2-GA互作的简单相加模型需要考虑这些O-2对激素敏感性的影响，以解释实际的萌发模式。这些O-2、ABA和GA敏感性之间的定量和交互关系提供了深入了解休眠和萌发是如何受到物理(O-2通过壳体扩散)和生理(ABA和GA敏感性)因素组合调控的。
Barley (Hordeum vulgare L.) seeds (grains) exhibit dormancy at maturity that is largely due to the presence of the glumellae (hulls) that reduce the availability of oxygen (O-2) to the embryo. In addition, abscisic acid (ABA) and gibberellins (GAS) interact with O-2 to regulate barley seed dormancy. A population-based threshold model was applied to quantify the sensitivities of seeds and excised embryos to O-2, ABA, and GA, and to their interactive effects. The median O-2 requirement for germination of dormant intact barley seeds was 400-fold greater than for excised embryos, indicating that the tissues enclosing the embryo markedly limit O-2 penetration. However, embryo O-2 thresholds decreased by another order of magnitude following after-ripening. Thus, increases in both permeability of the hull to O-2 and embryo sensitivity to O-2 contribute to the improvement in germination capacity during after-ripening. Both ABA and GA had relatively small effects on the sensitivity of germination to O-2, but ABA and GA thresholds varied over several orders of magnitude in response to O-2 availability, with sensitivity to ABA increasing and sensitivity to GA decreasing with hypoxia. Simple additive models of O-2-ABA and O-2-GA interactions required consideration of these O-2 effects on hormone sensitivity to account for actual germination patterns. These quantitative and interactive relationships among O-2, ABA, and GA sensitivities provide insight into how dormancy and germination are regulated by a combination of physical (O-2 diffusion through the hull) and physiological (ABA and GA sensitivities) factors.