Herrera-Rodríguez María Begoña, Pérez-Vicente Rafael, Maldonado José-María
Departamento de Fisiología, Anatomía y Biología Celular, Area de Fisiología Vegetal, Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, Ctra. de Utrera. km 1, 41013 Sevilla, Spain.
Plant Physiol Biochem. 2007 Jan;45(1):33-8. doi: 10.1016/j.plaphy.2006.12.002. Epub 2006 Dec 28.
In sunflower, asparagine synthetase (AS; EC 6.3.5.4) is encoded by a small family of three genes (HAS1, HAS1.1 and HAS2) that are differentially regulated by light, carbon and nitrogen availability. In this study, the response of each gene to various stress conditions was examined by Northern analysis with gene-specific probes in leaves and roots. The expression of HAS1 and HAS1.1 genes was induced by osmotic stress (300 mM mannitol), salt stress (150 mM NaCl), and heavy-metal stress (20 microM CuSO(4)), more in roots than in leaves. The expression of HAS2 was not significantly altered by stress treatments. The positive response of HAS1 and HAS1.1 genes to osmotic and salt stresses occurred in the light, in contrast to that previously found in unstressed plants. Measurements of sucrose and total free amino acid contents in leaves and roots indicate that the expression of root HAS1 and HAS1.1 genes in stressed plants is not under metabolic control by the intracellular C/N ratio, suggesting the involvement of some specific stress factor(s). Growth of plants at 40 degrees C for 12h negatively affected the expression of HAS1 and HAS1.1 but not that of HAS2.
在向日葵中，天冬酰胺合成酶（AS；EC 6.3.5.4）由一个包含三个基因（HAS1、HAS1.1和HAS2）的小基因家族编码，这些基因受光照、碳源和氮源的可用性差异调控。在本研究中，通过使用基因特异性探针进行Northern分析，检测了每个基因在叶片和根中对各种胁迫条件的响应。HAS1和HAS1.1基因的表达受渗透胁迫（300 mM甘露醇）、盐胁迫（150 mM NaCl）和重金属胁迫（20 μM CuSO₄）诱导，在根中的诱导程度高于叶片。HAS2的表达在胁迫处理下没有显著变化。与之前在未受胁迫植物中发现的情况相反，HAS1和HAS1.1基因对渗透胁迫和盐胁迫的正向响应发生在光照条件下。对叶片和根中蔗糖和总游离氨基酸含量的测量表明，胁迫植物中根HAS1和HAS1.1基因的表达不受细胞内C/N比的代谢控制，这表明存在一些特定的胁迫因子。植物在40℃下生长12小时对HAS1和HAS1.1的表达有负面影响，但对HAS2的表达没有影响。
