Logemann E, Wu S C, Schröder J, Schmelzer E, Somssich I E, Hahlbrock K
Max-Planck-Institut für Züchtungsforschung, Abteilung Biochemie, Köln, Germany.
Plant J. 1995 Dec;8(6):865-76. doi: 10.1046/j.1365-313x.1995.8060865.x.
The effects of UV light or fungal elicitors on plant cells have so far been studied mostly with respect to defense-related gene activation. Here, an inverse correlation of these stimulatory effects with the activities of several cell cycle-related genes is demonstrated. Concomitant with the induction of flavonoid biosynthetic enzymes in UV-irradiated cell suspension cultures of parsley (Petroselinum crispum), total histone synthesis declined to about half the initial rate. A subclass of the histone H3 gene family was selected to demonstrate the close correlation of its expression with cell division, both in intact plants and cultured cells. Using RNA-blot and run-on transcription assays, it was shown that one arbitrarily selected subclass of each of the histone H2A, H2B, H3 and H4 gene families and of the genes encoding a p34cdc2 protein kinase and a mitotic cyclin were transcriptionally repressed in UV-irradiated as well as fungal elicitor-treated parsley cells. The timing and extent of repression differed between the two stimuli; the response to light was more transient and smaller in magnitude. These differential responses to light and elicitor were inversely correlated with the induction of phenylalanine ammonia-lyase, a key enzyme of phenylpropanoid metabolism. Essentially the same result was obtained with a defined oligopeptide elicitor, indicating that the same signaling pathway is responsible for defense-related gene activation and cell cycle-related gene repression. A temporary (UV light) or long-lasting (fungal elicitor) cessation of cell culture growth is most likely due to an arrest of cell division which may be a prerequisite for full commitment of the cells to transcriptional activation of full commitment of the cells to transcriptional activation of pathways involved in UV protection or pathogen defense. This conclusion is corroborated by the observation that the histone H3 mRNA level greatly declined around fungal infection sites in young parsley leaves.
到目前为止，紫外线或真菌激发子对植物细胞的影响主要是针对与防御相关的基因激活进行研究的。在此，证明了这些刺激效应与几个细胞周期相关基因的活性呈负相关。在紫外线照射的欧芹（Petroselinum crispum）细胞悬浮培养物中，伴随着类黄酮生物合成酶的诱导，总组蛋白合成下降至初始速率的约一半。选择组蛋白H3基因家族的一个亚类来证明其在完整植物和培养细胞中表达与细胞分裂的密切相关性。使用RNA印迹和连续转录分析表明，在紫外线照射以及真菌激发子处理的欧芹细胞中，组蛋白H2A、H2B、H3和H4基因家族以及编码p34cdc2蛋白激酶和有丝分裂周期蛋白的基因中，任意选择的一个亚类在转录上受到抑制。两种刺激之间抑制的时间和程度不同；对光的反应更短暂且幅度更小。对光和激发子的这些差异反应与苯丙烷代谢的关键酶苯丙氨酸解氨酶的诱导呈负相关。用一种确定的寡肽激发子获得了基本相同的结果，表明相同的信号通路负责与防御相关的基因激活和与细胞周期相关的基因抑制。细胞培养生长的暂时（紫外线）或持久（真菌激发子）停止很可能是由于细胞分裂的停滞，这可能是细胞完全致力于紫外线保护或病原体防御相关途径转录激活的先决条件。在幼嫩欧芹叶片的真菌感染部位周围组蛋白H3 mRNA水平大幅下降这一观察结果证实了这一结论。
