Intracellular Ca2+ plays an essential role in plant cellular sensing of various environmental stress signals by modulating the activity of Ca2+-binding proteins. Leymus chinensis is a dominant forage grass widely distributed in the Eurasian Steppe that is well adapted to drought and salty soils common in the region. Through transcript profiling of L. chinensis roots, we identified a transcript predicted to encode histidine-rich calcium-binding protein (HRC), a protein recently characterized in wheat. L. chinensis HRC (LcH RC) localized in the nucleus, as demonstrated using a transient gene expression method that we developed for this species. Different regions of LcHRC showed affinity for either Ca2+ or Zn2+, but not Mg2+ and Mn2+. Arabidopsis thaliana seedlings heterologously overexpressing LcHRC showed greater sensitivity to abscisic acid (ABA), along with decreased expression of some ABA-induced marker genes, but no increase in ABA content. Screening a Arabidopsis cDNA yeast library identified a Tudor/PWWP/MBT-domain-containing protein (AtPWWP3) that interacts with LcHRC. AtPWWP3 also localized in the nucleus and is predicted to mediate gene expression by modifying histone deacetylation. Based on these results, we propose a functional model of LcHRC action.

中文翻译：

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羊草富含组氨酸的 Ca2+ 结合蛋白结合 Ca2+/Zn2+ 并抑制拟南芥中的脱落酸信号

细胞内 Ca2+ 通过调节 Ca2+ 结合蛋白的活性，在植物细胞感知各种环境胁迫信号中发挥重要作用。羊草是一种广泛分布于欧亚草原的优势牧草，能很好地适应该地区常见的干旱和盐碱地。通过对 L. chinensis 根的转录谱分析，我们确定了一个预测编码富含组氨酸的钙结合蛋白 (HRC) 的转录物，这是一种最近在小麦中表征的蛋白质。L. chinensis HRC (LcH RC) 位于细胞核中，正如使用我们为该物种开发的瞬时基因表达方法所证明的那样。LcHRC 的不同区域显示出对 Ca2+ 或 Zn2+ 的亲和力，但对 Mg2+ 和 Mn2+ 没有亲和力。异源过表达 LcHRC 的拟南芥幼苗对脱落酸 (ABA) 表现出更高的敏感性，随着一些 ABA 诱导的标记基因的表达降低，但 ABA 含量没有增加。筛选拟南芥 cDNA 酵母文库确定了与 LcHRC 相互作用的含有 Tudor/PWWP/MBT 域的蛋白质 (AtPWWP3)。AtPWWP3 也位于细胞核中，预计通过修饰组蛋白去乙酰化来介导基因表达。基于这些结果，我们提出了 LcHRC 行动的功能模型。