Ascenzi R, Gantt J S
Department of Plant Biology, University of Minnesota, St. Paul 55108, USA.
Plant Mol Biol. 1999 Sep;41(2):159-69. doi: 10.1023/a:1006302330879.
Linker histones are ubiquitous structural components of chromatin that have been shown to influence the expression of a subset of genes in diverse organisms. Plants contain a minor linker histone variant that is expressed in most tissues of all organs, and is induced during drought stress. Based on reporter gene analysis in roots, His1-3 is expressed almost exclusively in emerging secondary roots in unstressed plants, but is primarily expressed in the root meristem and elongation zone of stressed plants. In shoots, expression is higher in younger tissues than older tissues. In order to investigate the function of H1-3, we have generated lines with altered levels of H1-3. Plants expressing an antisense His1-3 transcript exhibit a greatly impaired induction (5% of wild-type RNA levels during stress) of His1-3 transcripts in shoots during drought and contain decreased protein relative to wild-type control plants. In plants overexpressing His1-3, more H1-3 is bound to chromatin than in unstressed wild-type plants. None of the plants containing these transgenes display phenotypic aberrations or differences in water content during drought stress. Additionally, the expression of several drought-responsive genes is not significantly altered in lines misexpressing His1-3.
连接组蛋白是染色质中普遍存在的结构成分，已被证明会影响多种生物体中一部分基因的表达。植物含有一种次要的连接组蛋白变体，在所有器官的大多数组织中都有表达，并在干旱胁迫期间被诱导表达。基于根中的报告基因分析，His1-3在未受胁迫的植物中几乎只在新出现的侧根中表达，但在受胁迫的植物中主要在根分生组织和伸长区表达。在茎中，年轻组织中的表达高于老组织。为了研究H1-3的功能，我们构建了H1-3水平改变的株系。表达反义His1-3转录本的植物在干旱期间茎中His1-3转录本的诱导表达严重受损（胁迫期间为野生型RNA水平的5%），并且相对于野生型对照植物，其蛋白质含量降低。在过表达His1-3的植物中，与未受胁迫的野生型植物相比，更多的H1-3与染色质结合。含有这些转基因的植物在干旱胁迫期间均未表现出表型异常或含水量差异。此外，在错误表达His1-3的株系中，几个干旱响应基因的表达没有明显改变。
