Termination of hull-imposed dormancy in developing barley grains is correlated with changes in embryonic ABA levels and sensitivity
Termination of hull-imposed dormancy in developing barley grains is correlated with changes in embryonic ABA levels and sensitivity
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DOI：
10.1017/s0960258599000045
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发表时间：
1999-03-01
影响因子：
2.1
通讯作者：
Rodriguez, V
中科院分区：
文献类型：
--
作者：
Benech-Arnold, RL;Giallorenzi, MC;Rodriguez, V
我们研究了两个商业大麦品种 B 1215 和 Quilmes Palomar 的籽粒发育过程中休眠的变化（由胚乳、果皮和胚芽等不同结构引起）及其与胚胎 ABA 水平和敏感性变化的关系，这两个品种在收获时分别具有低和高的休眠水平，因此在多雨年份具有对比的发芽行为。在两个品种的整个发育过程中，由胚乳和果皮造成的休眠逐渐且类似地减轻。相比之下，壳（荚膜）的存在完全抑制了两个品种谷物的发芽，直到生理成熟（PM）。从那时起，B 1215 谷物中由外壳强加的休眠突然被解除，而 Q. Palomar 谷物中的休眠被解除的速度要低得多。这种差异决定了这两个品种在从下午到作物收获的“时间窗口”内的不同发芽行为。两个品种在整个发育过程中直至 PM 的胚胎 ABA 含量和敏感性相似。从那时起，B 1215 胚胎中的 ABA 含量和敏感性急剧下降，与该品种中观察到的外壳强制休眠的突然终止同时发生。相比之下，Q. Palomar 胚胎中的 ABA 水平在较长时间内保持较高水平，并且对 ABA 的敏感性下降速度要慢得多。这种相关性表明，大麦的外壳休眠可能受到胚胎 ABA 水平和/或敏感性的调节。花后施用多效唑抑制 GA 合成，降低了两个品种谷粒的发芽能力，但未改变裸露颖果的发芽能力，从而进一步表明壳强加的休眠是在激素控制下的。
We studied changes in dormancy (as imposed by the different structures surrounding the embryo, namely, endosperm, pericarp and glumellae) and its relationship with changes in embryonic ABA levels and sensitivity, in developing grains of two commercial barley cultivars: B 1215 and Quilmes Palomar, which have, respectively, a low and high dormancy level at harvest and, consequently, a contrasting sprouting behaviour in rainy years. Dormancy imposed by endosperm plus pericarp was gradually and similarly alleviated throughout development in both cultivars. The presence of the hull (glumellae), in contrast, completely inhibited germination of grains from both cultivars until physiological maturity (PM). From there on, hull-imposed dormancy was removed abruptly in B 1215 grains, while in Q. Palomar ones, it was removed at a much lower rate. This difference determined the contrasting sprouting behaviour of these two cultivars within the 'time window' going from PM to crop harvest. Embryonic ABA content and sensitivity were similar in the two cultivars throughout development until PM. From there on, ABA content and sensitivity in B 1215 embryos declined dramatically coinciding with the abrupt termination of hull-imposed dormancy observed in this cultivar. In contrast, ABA levels in Q. Palomar embryos remained high for longer and sensitivity to ABA declined at a much slower rate. This correlation suggests that hull-imposed dormancy in barley might be regulated by embryonic ABA levels and / or sensitivity. Inhibition of GA synthesis with paclobutrazol applied after anthesis lowered the germination capacity of grains from both cultivars without altering that of the naked caryopses, thus further suggesting that hull-imposed dormancy is under hormonal control.