Pectin has been extensively studied in animal immunity, and exogenous pectin as a food additive can provide protection against inflammatory bowel disease. However, the utility of pectin to improve immunity in plants is still unstudied. Here, we found exogenous application of pectin triggered stomatal closure in Arabidopsis in a dose‐ and time‐dependent manner. Additionally, pectin activated peroxidase and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to produce reactive oxygen species (ROS), which subsequently increased cytoplasmic Ca2+ concentration ([Ca2+]cyt) and was followed by nitric oxide (NO) production, leading to stomatal closure in an abscisic acid (ABA) and salicylic acid (SA) signalling‐dependent mechanism. Furthermore, pectin enhanced the disease resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) with mitogen‐activated protein kinases (MPKs) MPK3/6 activated and upregulated expression of defence‐responsive genes in Arabidopsis. These results suggested that exogenous pectin‐induced stomatal closure was associated with ROS and NO production regulated by ABA and SA signalling, contributing to defence against Pst DC3000 in Arabidopsis.

中文翻译：

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外源应用果胶触发拟南芥气孔关闭和免疫

果胶在动物免疫方面已被广泛研究，外源果胶作为食品添加剂可以提供针对炎症性肠病的保护作用。然而，果胶在提高植物免疫力方面的效用尚未得到研究。在这里，我们发现果胶的外源应用引发了气孔关闭拟南芥以剂量和时间依赖性方式。此外，果胶激活过氧化物酶和烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶产生活性氧（ROS），随后增加细胞质 Ca2+2+浓度（[Ca2+]细胞色素），然后产生一氧化氮（NO），导致脱落酸（ABA）和水杨酸（SA）信号依赖机制中的气孔关闭。此外，果胶还增强了抗病能力丁香假单胞菌光伏。番茄DC3000 (Pst DC3000) 与丝裂原激活蛋白激酶 (MPK) MPK3/6 激活并上调防御反应基因的表达拟南芥。这些结果表明，外源果胶诱导的气孔关闭与 ABA 和 SA 信号调节的 ROS 和 NO 产生相关，有助于防御 Pst DC3000拟南芥。