细胞质葡萄糖-6-磷酸脱氢酶缺失增加拟南芥对根结线虫感染的易感性。
Loss of cytosolic glucose-6-phosphate dehydrogenase increases the susceptibility of Arabidopsis thaliana to root-knot nematode infection.
机构信息
Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China.
College of Life Sciences, Northwest A&F University, Yangling, Shanxi, China.
出版信息
Ann Bot. 2019 Jan 1;123(1):37-46. doi: 10.1093/aob/mcy124.
BACKGROUND AND AIMS
Root knot nematodes (RKNs, Meloidogyne spp.) are microscopic roundworms with a wide host range causing great economic losses worldwide. Understanding how metabolic pathways function within the plant upon RKN infection will provide insight into the molecular aspects of plant-RKN interactions. Glucose-6-phosphate dehydrogenase (G6PDH), the key regulatory enzyme of the oxidative pentose phosphate pathway (OPPP), is involved in plant responses to abiotic stresses and pathogenesis. In this study, the roles of Arabidopsis cytosolic G6PDH in plant-RKN interactions were investigated.
METHODS
Enzyme assays and western blotting were used to characterize changes in total G6PDH activity and protein abundance in wild-type Arabidopsis in response to RKN infection. The susceptibility of wild-type plants and the double mutant g6pd5/6 to RKNs was analysed and the expression of genes associated with the basal defence response was tested after RKN infection using quantitative reverse transcription PCR.
KEY RESULTS
RKN infection caused a marked increase in total G6PDH activity and protein abundance in wild-type Arabidopsis roots. However, the transcript levels of G6PDH genes except G6PD6 were not significantly induced following RKN infection, suggesting that the increase in G6PDH activity may occur at the post-transcriptional level. The double mutant g6pd5/6 with loss-of-function of the two cytosolic isoforms G6PD5 and G6PD6 displayed enhanced susceptibility to RKNs. Moreover, reactive oxygen species (ROS) production and gene expression involved in the defence response including jasmonic acid and salicylic acid pathways were suppressed in the g6pd5/6 mutant at the early stage of RKN infection when compared to the wild-type plants.
CONCLUSIONS
The results demonstrated that the G6PDH-mediated OPPP plays an important role in the plant-RKN interaction. In addition, a new aspect of G6PDH activity involving NADPH production by the OPPP in plant basal defence against RKNs is defined, which may be involved in ROS signalling.
背景与目的
根结线虫（RKNs，Meloidogyne spp.）是一种微小的圆形蠕虫，宿主范围广泛，在全球范围内造成了巨大的经济损失。了解 RKN 感染后植物代谢途径的功能将为植物与 RKN 相互作用的分子方面提供深入了解。葡萄糖-6-磷酸脱氢酶（G6PDH）是氧化戊糖磷酸途径（OPPP）的关键调节酶，参与植物对非生物胁迫和发病机制的反应。在这项研究中，研究了拟南芥细胞质 G6PDH 在植物与 RKN 相互作用中的作用。
方法
使用酶测定法和 Western blot 分析来表征野生型拟南芥对 RKN 感染的总 G6PDH 活性和蛋白丰度的变化。分析了野生型植物和双突变体 g6pd5/6 对 RKN 的敏感性，并在 RKN 感染后使用定量逆转录 PCR 测试与基础防御反应相关的基因的表达。
主要结果
RKN 感染导致野生型拟南芥根中总 G6PDH 活性和蛋白丰度显著增加。然而，除 G6PD6 之外，G6PDH 基因的转录水平在 RKN 感染后没有显著诱导，表明 G6PDH 活性的增加可能发生在转录后水平。失去两个细胞质同工型 G6PD5 和 G6PD6 的双突变体 g6pd5/6 对 RKN 的敏感性增强。此外，与野生型植物相比，在 RKN 感染的早期阶段，g6pd5/6 突变体中与防御反应相关的活性氧（ROS）产生和基因表达（包括茉莉酸和水杨酸途径）受到抑制。
结论
结果表明，G6PDH 介导的 OPPP 在植物与 RKN 相互作用中起重要作用。此外，定义了 G6PDH 活性的一个新方面，涉及 OPPP 产生 NADPH 以抵御 RKNs 的植物基础防御，这可能涉及 ROS 信号转导。
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