Department of Plant Sciences, Weizmann Institute of Science, Rehovot, Israel.
New Phytol. 2011 Jan;189(1):148-59. doi: 10.1111/j.1469-8137.2010.03478.x. Epub 2010 Oct 11.
• Lysine is a nutritionally important essential amino acid, but significant elevation of its levels in Arabidopsis seeds, by enhancing its synthesis and blocking its catabolism, causes a retardation of germination. Here, we hypothesized that this negative effect is associated with changes in primary metabolism and gene expression programs that are essential for early germination. • Seeds at different stages of germination sensu stricto of the seed-high-lysine genotype were subjected to detailed analysis of primary metabolism, using GC-MS, as well as microarray analysis and two-dimensional, isoelectric focusing, sodium dodecylsulfate polyacrylamide gel electrophoresis, to detect storage protein mobilization. • Our results exposed a major negative effect of the seed-specific increased lysine synthesis and knockout of its catabolism on the levels of a number of TCA cycle metabolites. This metabolic alteration also influences significantly the transcriptome, primarily attenuating the boost of specific transcriptional programs that are essential for seedling establishment, such as the onset of photosynthesis, as well as the turnover of specific transcriptional programs associated with seed embryonic traits. • Our results indicate that catabolism of the aspartic acid family of amino acids is an important contributor to the energy status of plants, and hence to the onset of autotrophic growth-associated processes during germination.
赖氨酸是一种营养上重要的必需氨基酸,但通过增强其合成并阻断其分解代谢,使拟南芥种子中的赖氨酸水平显著升高,会导致发芽延迟。在这里,我们假设这种负效应与对早期发芽至关重要的初级代谢和基因表达程序的变化有关。
对种子高赖氨酸基因型种子发芽过程中不同阶段进行了详细的初级代谢分析,使用 GC-MS 以及微阵列分析和二维、等电聚焦、十二烷基硫酸钠聚丙烯酰胺凝胶电泳,以检测贮藏蛋白的动员。
我们的结果表明,种子特异性增加的赖氨酸合成和分解代谢的敲除对 TCA 循环代谢物的水平有很大的负面影响。这种代谢变化也显著影响转录组,主要是减弱了对幼苗建立至关重要的特定转录程序的促进,例如光合作用的开始,以及与种子胚胎特征相关的特定转录程序的转换。
我们的结果表明,天冬氨酸族氨基酸的分解代谢是植物能量状态的一个重要贡献者,因此也是发芽过程中自养生长相关过程开始的一个重要贡献者。