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首页> 外文期刊>Journal of Experimental Botany >Expression of gibberellin 20-oxidase1 (AtGA20ox1) in Arabidopsis seedlings with altered auxin status is regulated at multiple levels
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Expression of gibberellin 20-oxidase1 (AtGA20ox1) in Arabidopsis seedlings with altered auxin status is regulated at multiple levels

机译：生长素状态改变的拟南芥幼苗中赤霉素20-氧化酶1（AtGA20ox1）的表达受到多个水平的调节。

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摘要

Bioactive gibberellins (GAs) affect many biological processes including germination, stem growth, transition to flowering, and fruit development. The location, timing, and level of bioactive GA are finely tuned to ensure that optimal growth and development occur. The balance between GA biosynthesis and deactivation is controlled by external factors such as light and by internal factors that include auxin. The role of auxin transport inhibitors (ATIs) and auxins on GA homeostasis in intact light-grown Arabidopsis thaliana (L.) Heynh. seedlings was investigated. Two ATIs, 1-N-naphthylthalamic acid (NPA) and 1-naphthoxyacetic acid (NOA) caused elevated expression of the GA biosynthetic enzyme AtGA20-oxidase1 (AtGA20ox1) in shoot but not in root tissues, and only at certain developmental stages. It was investigated whether enhanced AtGA20ox1 gene expression was a consequence of altered flow through the GA biosynthetic pathway, or was due to impaired GA signalling that can lead to enhanced AtGA20ox1 expression and accumulation of a DELLA protein, Repressor of ga1-3 (RGA). Both ATIs promoted accumulation of GFP-fused RGA in shoots and roots, and this increase was counteracted by the application of GA4. These results suggest that in ATI-treated seedlings the impediment to DELLA protein degradation may be a deficiency of bioactive GA at sites of GA response. It is proposed that the four different levels of AtGA20ox1 regulation observed here are imposed in a strict hierarchy: spatial (organ-, tissue-, cell-specific) developmental metabolic auxin regulation. Thus results show that, in intact auxin- and auxin transport inhibitor-treated light-grown Arabidopsis seedlings, three other levels of regulation supersede the effects of auxin on AtGA20ox1.
机译：具有生物活性的赤霉素（GAs）影响许多生物过程，包括发芽，茎生长，过渡到开花和果实发育。对生物活性GA的位置，时间和水平进行了微调，以确保发生最佳的生长和发育。 GA生物合成和失活之间的平衡受外部因素（例如光）和内部因素（包括生长素）的控制。生长素运输抑制剂（ATIs）和生长素在完整的轻度生长拟南芥（L.）Heynh中对GA稳态的作用。调查了幼苗。两种ATIs，即1-N-萘甲基卤代氨基甲酸（NPA）和1-萘氧基乙酸（NOA）导致了GA生物合成酶AtGA20-氧化酶1（AtGA20ox1）在芽中表达升高，但在根部组织中却没有表达，仅在某些发育阶段。研究了增强的AtGA20ox1基因表达是由于流经GA生物合成途径的流量改变的结果，还是归因于GA信号传导受损，从而导致增强的AtGA20ox1表达和DELLA蛋白，ga1-3阻遏物（RGA）的积累。两种ATI均可促进GFP融合的RGA在芽和根中的积累，而GA 4 的添加抵消了这种增加。这些结果表明，在ATI处理的幼苗中，DELLA蛋白降解的障碍可能是GA响应位点缺乏生物活性GA的原因。建议将此处观察到的四个不同水平的AtGA20ox1调控作用于严格的层次结构中：空间（器官，组织，细胞特异性）>发育>代谢>生长素调控。因此结果表明，在完整的生长素和生长素转运抑制剂处理的轻度生长的拟南芥幼苗中，其他三个调节水平取代了生长素对AtGA20ox1的作用。

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