A characteristic feature of a plant immune response is the increase of the cytosolic calcium (Ca2+) concentration following infection, which results in the downstream activation of immune response regulators. The bryophyte Physcomitrella patens has been shown to mount an immune response when exposed to bacteria, fungi, or chitin elicitation, in a manner similar to the one observed in Arabidopsis thaliana. Nevertheless, whether the response of P. patens to microorganism exposure is Ca2+ mediated is currently unknown. Here, we show that P. patens plants treated with chitin oligosaccharides exhibit Ca2+ oscillations, and that a calcium ionophore can stimulate the expression of defense-related genes. Treatment with chitin oligosaccharides also results in an inhibition of growth, which can be explained by the depolymerization of the apical actin cytoskeleton of tip growing cells. These results suggest that chitin-triggered calcium oscillations are conserved and were likely present in the common ancestor of bryophytes and vascular plants.

中文翻译：

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几丁质触发植物假单胞菌中钙介导的免疫反应。

植物免疫应答的一个特征是感染后胞浆钙（Ca2 +）浓度增加，这导致免疫应答调节剂的下游激活。苔藓植物小立碗藓已经显示出当暴露于细菌，真菌或几丁质诱导下时会产生免疫反应，其方式类似于拟南芥中观察到的方式。然而，目前尚不清楚彭氏疟原虫对微生物暴露的反应是否是Ca 2+介导的。在这里，我们显示用几丁质寡糖处理的彭定康植物显示出Ca2 +振荡，并且钙离子载体可以刺激防御相关基因的表达。几丁质寡糖的治疗还可以抑制生长，这可以通过尖端生长细胞的顶端肌动蛋白细胞骨架解聚来解释。这些结果表明，几丁质触发的钙振荡是保守的，并且很可能存在于苔藓植物和维管植物的共同祖先中。