Albertos Pablo, Romero-Puertas María C, Tatematsu Kiyoshi, Mateos Isabel, Sánchez-Vicente Inmaculada, Nambara Eiji, Lorenzo Oscar
Dpto. de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Facultad de Biología, Universidad de Salamanca, C/ Río Duero 12, Salamanca 37185, Spain.
Dpto. de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Profesor Albareda 1, Granada E-18008, Spain.
Nat Commun. 2015 Oct 23;6:8669. doi: 10.1038/ncomms9669.
Plant survival depends on seed germination and progression through post-germinative developmental checkpoints. These processes are controlled by the stress phytohormone abscisic acid (ABA). ABA regulates the basic leucine zipper transcriptional factor ABI5, a central hub of growth repression, while the reactive nitrogen molecule nitric oxide (NO) counteracts ABA during seed germination. However, the molecular mechanisms by which seeds sense more favourable conditions and start germinating have remained elusive. Here we show that ABI5 promotes growth via NO, and that ABI5 accumulation is altered in genetic backgrounds with impaired NO homeostasis. S-nitrosylation of ABI5 at cysteine-153 facilitates its degradation through CULLIN4-based and KEEP ON GOING E3 ligases, and promotes seed germination. Conversely, mutation of ABI5 at cysteine-153 deregulates protein stability and inhibition of seed germination by NO depletion. These findings suggest an inverse molecular link between NO and ABA hormone signalling through distinct posttranslational modifications of ABI5 during early seedling development.
植物的存活依赖于种子萌发以及通过萌发后的发育检查点。这些过程受胁迫植物激素脱落酸（ABA）的调控。ABA调节碱性亮氨酸拉链转录因子ABI5，它是生长抑制的核心枢纽，而活性氮分子一氧化氮（NO）在种子萌发过程中拮抗ABA。然而，种子感知更有利条件并开始萌发的分子机制仍然不清楚。在这里，我们表明ABI5通过NO促进生长，并且在NO稳态受损的遗传背景中ABI5的积累发生改变。ABI5第153位半胱氨酸的S-亚硝基化促进其通过基于CULLIN4和KEEP ON GOING的E3连接酶降解，并促进种子萌发。相反，ABI5第153位半胱氨酸的突变会解除蛋白质稳定性的调控，并通过耗尽NO抑制种子萌发。这些发现表明，在幼苗早期发育过程中，通过对ABI5进行不同的翻译后修饰，NO和ABA激素信号之间存在反向分子联系。
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