Cheng J C, Seeley K A, Goupil P, Sung Z R
Department of Plant Biology, University of California Berkeley 94720, USA.
Plant Mol Biol. 1996 Apr;31(1):127-41. doi: 10.1007/BF00020612.
DC8 is a late embryogenesis-abundant (LEA) protein gene isolated from carrot (Daucus carota). Deletion analysis of the DC8 promoter was performed to determine the sequences required for ABA and seed-specific regulation of DC8 transcription. To investigate the mechanism of DC8 expression during seed development, chimeric gene constructs containing DC8 promoter fragments fused to a promoterless beta-glucuronidase gene (DC8:GUS) were introduced into carrot, tobacco (Nicotiana tobacum) and Arabidopsis thaliana plants. Seed-specific DC8 expression patterns was conserved among the three plant species. However, differences among the species in the patterns of DC8 expression in the embryo and endosperm that correlated with differences in the rates of embryo and endosperm growth were found. Lack of correspondence between DC8 activation and embryo development among the seeds of the three species suggests that DC8 expression, which is associated with seed maturation, is not coupled to the embryo development program. The presence of DC8 activity in carrot callus and endosperm is consistent with the notion that DC8 expression is independent of embryo morphogenesis. A similar DC8 activity time-course during callus induction and seed development suggests that explantation and 2,4-D treatment initiates a course of events similar to that in the carrot ovule. After fertilization, two pathways one leading to embryo development and another to seed maturation are initiated, but they are not closely linked. As a result we find DC8, part of the maturation program, being activated at different embryonic stages in different plant species.
DC8是从胡萝卜（Daucus carota）中分离出的一个晚期胚胎发生丰富（LEA）蛋白基因。对DC8启动子进行缺失分析，以确定DC8转录的ABA和种子特异性调控所需的序列。为了研究种子发育过程中DC8表达的机制，将含有与无启动子β-葡萄糖醛酸酶基因融合的DC8启动子片段的嵌合基因构建体（DC8:GUS）导入胡萝卜、烟草（Nicotiana tobacum）和拟南芥植物中。种子特异性的DC8表达模式在这三种植物物种中是保守的。然而，发现这三个物种在胚胎和胚乳中DC8表达模式的差异与胚胎和胚乳生长速率的差异相关。三种物种种子中DC8激活与胚胎发育之间缺乏对应关系，这表明与种子成熟相关的DC8表达与胚胎发育程序没有关联。胡萝卜愈伤组织和胚乳中存在DC8活性，这与DC8表达独立于胚胎形态发生的观点一致。愈伤组织诱导和种子发育过程中类似的DC8活性时间进程表明，外植体和2,4-D处理引发了一系列类似于胡萝卜胚珠中的事件。受精后，启动了两条途径，一条导致胚胎发育，另一条导致种子成熟，但它们没有紧密联系。因此，我们发现作为成熟程序一部分的DC8在不同植物物种的不同胚胎阶段被激活。
