Aoyama T, Dong C H, Wu Y, Carabelli M, Sessa G, Ruberti I, Morelli G, Chua N H
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6339, USA.
Plant Cell. 1995 Nov;7(11):1773-85. doi: 10.1105/tpc.7.11.1773.
The Arabidopsis thaliana Athb-1 is a homeobox gene of unknown function. By analogy with homeobox genes of other organisms, its gene product, Athb-1, is most likely a transcription factor involved in developmental processes. We constructed a series of Athb-1-derived genes to examine the roles of Athb-1 in transcriptional regulation and plant development. Athb-1 was found to transactivate a promoter linked to a specific DNA binding site by transient expression assays. In transgenic tobacco plants, overexpression of Athb-1 or its chimeric derivatives with heterologous transactivating domains of the yeast transcription factor GAL4 or herpes simplex virus transcription factor VP16 conferred deetiolated phenotypes in the dark, including cotyledon expansion, true leaf development, and an inhibition of hypocotyl elongation. Expression of Athb-1 or the two chimeric derivatives also affected the development of palisade parenchyma under normal growth conditions, resulting in light green sectors in leaves and cotyledons, whereas other organs in the transgenic plants remained normal. Both developmental phenotypes were induced by glucocorticoid in transgenic plants expressing a chimeric transcription factor comprising the Athb-1 DNA binding domain, the VP16 transactivating domain, and the glucocorticoid receptor domain. Plants with severe inducible phenotypes showed additional abnormality in cotyledon expansion. Our results suggest that Athb-1 is a transcription activator involved in leaf development.
拟南芥Athb-1是一个功能未知的同源异型盒基因。通过与其他生物体的同源异型盒基因进行类比，其基因产物Athb-1很可能是一种参与发育过程的转录因子。我们构建了一系列源自Athb-1的基因，以研究Athb-1在转录调控和植物发育中的作用。通过瞬时表达分析发现，Athb-1能反式激活与特定DNA结合位点相连的启动子。在转基因烟草植株中，Athb-1或其与酵母转录因子GAL4的异源反式激活结构域或单纯疱疹病毒转录因子VP16的嵌合衍生物的过表达，在黑暗中赋予了去黄化表型，包括子叶扩展、真叶发育以及下胚轴伸长的抑制。在正常生长条件下，Athb-1或这两种嵌合衍生物的表达也影响了栅栏薄壁组织的发育，导致叶片和子叶出现浅绿色区域，而转基因植株的其他器官保持正常。在表达包含Athb-1 DNA结合结构域、VP16反式激活结构域和糖皮质激素受体结构域的嵌合转录因子的转基因植株中，这两种发育表型均由糖皮质激素诱导产生。具有严重诱导表型的植株在子叶扩展方面还表现出额外的异常。我们的结果表明，Athb-1是一种参与叶片发育的转录激活因子。
