O'Neill S D, Zheng C C
Division of Biological Sciences, University of California at Davis, 95616, USA.
Plant Mol Biol. 1998 May;37(2):235-41. doi: 10.1023/a:1005948406131.
The abundance of an mRNA encoding an HMG 1/2 protein from Pharbitis nil (HMG1) has been previously shown to be regulated by light and an endogenous rhythm in cotyledons. A second Pharbitis nil HMG cDNA (HMG2) was characterized. The sequence of HMG2 was 82% and 86% identical to HMG1 at the nucleotide and amino acid level, respectively. As with HMG1, HMG2 mRNA was detected in all vegetative tissues and was most abundant in roots. However, unlike HMG1, HMG2 mRNA abundance did not increase upon transfer of cotyledons to darkness and did not exhibit regulation by an endogenous circadian rhythm when maintained in continuous darkness over a 68 h period. Similarly, while the abundance of HMG1 mRNA during a dark period that induced photoperiodically controlled flowering was dramatically affected by brief light exposure (night break), this treatment had no effect on HMG2 mRNA abundance. Collectively, these data are consistent with a role of HMG1 in contributing to the circadian-regulated and/or dark-regulated gene expression with constitutive expression of HMG2 playing a housekeeping role in the general regulation of gene expression in Pharbitis nil cotyledons.
之前的研究表明，来自牵牛（HMG1）的编码HMG 1/2蛋白的mRNA丰度受子叶中的光和内源性节律调控。对牵牛的第二个HMG cDNA（HMG2）进行了表征。HMG2的序列在核苷酸和氨基酸水平上分别与HMG1有82%和86%的同一性。与HMG1一样，HMG2 mRNA在所有营养组织中均有检测到，且在根中最为丰富。然而，与HMG1不同的是，子叶转移到黑暗中后，HMG2 mRNA丰度并未增加，并且在连续黑暗中保持68小时期间，未表现出受内源性昼夜节律调控。同样，在诱导光周期控制开花的黑暗期，短暂光照（夜间中断）对HMG1 mRNA丰度有显著影响，但该处理对HMG2 mRNA丰度没有影响。总体而言，这些数据表明，HMG1在昼夜节律调节和/或黑暗调节的基因表达中发挥作用，而HMG2的组成型表达在牵牛子叶基因表达的一般调节中起看家作用。
