Reassessment of an Arabidopsis cell wall invertase inhibitor AtCIF1 reveals its role in seed germination and early seedling growth
Reassessment of an Arabidopsis cell wall invertase inhibitor AtCIF1 reveals its role in seed germination and early seedling growth
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DOI：
10.1007/s11103-015-0402-2
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发表时间：
2015
影响因子：
5.1
通讯作者：
Tao Su;Sebastian Wolf;Mei-Ling Han;Hongbo Zhao;Hongbin Wei;S. Greiner;T. Rausch
中科院分区：
文献类型：
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作者：
Tao Su;Sebastian Wolf;Mei-Ling Han;Hongbo Zhao;Hongbin Wei;S. Greiner;T. Rausch
在高等植物中，细胞壁转化酶（CWI）和液泡转化酶（VI）被认为是糖代谢和糖信号传导的重要参与者，从而影响源库相互作用、植物发育和对环境信号的响应。CWI和VI的表达水平是转录控制的，然而，这两种酶也受到转化酶抑制剂蛋白的翻译后控制。抑制蛋白在种子萌发和幼苗早期发育过程中的生理意义尚未完全清楚。在这里，我们证明了抑制剂亚型AtCIF 1对拟南芥种子萌发和早期幼苗生长的影响。在烟草表皮和转基因烟草根中表达AtCIF 1 YFP融合构建体后，AtCIF 1的主要靶点被定位于质外体。表达谱分析表明，AtCWI 1与AtCIF 1在萌发早期的种子中时空共表达。种子萌发被观察到加速独立的外源脱落酸（阿坝）在AtCIF 1功能丧失mucif 1 -1。这种效应与CWI活性的急剧增加一致incif 1 - 1突变体种子萌发后24小时，无论是在体外和在植物。因此，糖含量的定量表明，己糖水平显着提高发芽种子的cif 1 - 1突变体。进一步研究AtCIF 1过表达基因在拟南芥中的表达，发现CWI活性受到明显抑制，种子萌发延迟。因此，我们得出结论，CWI活性AtCIF 1的翻译后调制有助于通过微调蔗糖水解，并可能通过糖信号来协调种子萌发和早期幼苗生长。
In higher plants, cell wall invertase (CWI) and vacuolar invertase (VI) are recognized as essential players in sugar metabolism and sugar signaling, thereby affecting source-sink interactions, plant development and responses to environmental cues. CWI and VI expression levels are transcriptionally controlled; however, both enzymes are also subject to posttranslational control by invertase inhibitor proteins. The physiological significances of inhibitor proteins during seed germination and early seedling development are not yet fully understood. Here, we demonstrate that the inhibitor isoform AtCIF1 impacted on seed germination and early seedling growth inArabidopsis. The primary target of AtCIF1 was shown to be localized to the apoplast after expressing an AtCIF1 YFP-fusion construct in tobacco epidermis and transgenicArabidopsisroot. The analysis of expression patterns showed thatAtCWI1was co-expressed spatiotemporally withAtCIF1within the early germinating seeds. Seed germination was observed to be accelerated independently of exogenous abscisic acid (ABA) in theAtCIF1loss-of-function mutantcif1-1. This effect coincided with a drastic increase of CWI activity incif1-1mutant seeds by 24 h after the onset of germination, both in vitro andin planta. Accordingly, quantification of sugar content showed that hexose levels were significantly boosted in germinating seeds of thecif1-1mutant. Further investigation ofAtCIF1overexpressors inArabidopsisrevealed a markedly suppressed CWI activity as well as delayed seed germination. Thus, we conclude that the posttranslational modulation of CWI activity by AtCIF1 helps to orchestrate seed germination and early seedling growth via fine-tuning sucrose hydrolysis and, possibly, sugar signaling.