DELLA proteins are repressors of the gibberellin (GA) hormone signaling pathway that act mainly by regulating transcription factor activities in plants. GAs induce DELLA repressor protein degradation and thereby control a number of critical developmental processes as well as stress responses such as cold stress. The strong impact of cold temperatures on many physiological processes has rendered it difficult to assess, based on phenotypic criteria, the role of GA and DELLAs in plant growth during cold stress. Here, we uncover substantial differences in the GA transcriptomes between plants grown at ambient temperature (21°C) and plants exposed to cold stress (4°C). We further identify over 250, to the largest extent new, DELLA-transcription factor interactions using the yeast two-hybrid system. By integrating both data sets, we reveal that most members of the nine-membered GRF (GROWTH REGULATORY FACTOR) transcription factor family are DELLA interactors and, at the same time, that several GRFs are targets of DELLA-modulated transcription after exposure to cold stress. We find that plants with altered GRF dosage are differentially sensitive to the manipulation of GA and hence DELLA levels, also after cold stress, and identify a subset of cold stress-responsive genes that qualify as targets of this DELLA-GRF regulatory module.

DELLA蛋白是赤霉素（GA）激素信号通路的阻遏物，主要通过调节植物中的转录因子活性发挥作用。GA诱导DELLA阻遏蛋白降解，从而控制许多关键的发育过程以及应激反应（例如冷应激）。寒冷对许多生理过程的强烈影响使得根据表型标准难以评估GA和DELLA在寒冷胁迫下植物生长中的作用。在这里，我们发现在环境温度（21°C）下生长的植物和暴露于冷胁迫（4°C）的植物之间的GA转录组存在显着差异。我们进一步确定使用酵母双杂交系统在最大程度上超过250种新的DELLA转录因子相互作用。通过整合两个数据集，我们揭示了九元GRF（生长调节因子）转录因子家族的大多数成员是DELLA相互作用子，同时，几个GRF在暴露于冷应激后成为DELLA调节转录的目标。我们发现具有改变的GRF剂量的植物对GA的操纵差异敏感，因此对冷胁迫后的DELLA水平也有差异，并鉴定出有资格作为该DELLA-GRF调控模块目标的冷胁迫响应基因子集。