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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #318403

Title: A novel nematode effector suppresses plant immunity by activating host reactuve oxygen species-scavenging system

item LIN, BORONG - South China Agricultural University
item ZHUO, KAN - South China Agricultural University
item CHEN, SHIYAN - Cornell University - New York
item HU, LILI - South China Agricultural University
item SUN, LONGHUA - South China Agricultural University
item Wang, Xiaohong
item ZHANG, LIAN-HUI - Imcb: Institute Of Molecular And Cell Biology
item LIAO, JINLING - South China Agricultural University

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2015
Publication Date: 10/20/2015
Citation: Lin, B., Zhuo, K., Chen, S., Hu, L., Sun, L., Wang, X., Zhang, L., Liao, J. 2015. A novel nematode effector suppresses plant immunity by activating host reactuve oxygen species-scavenging system. New Phytologist. 209:1159-1173.

Interpretive Summary: Root-knot nematodes (RKNs) (Meloidogyne spp.) are the most important nematode pathogens causing significant crop losses worldwide. These nematodes deliver effector proteins through their stylet into host root cells to promote infection. In this study, we utilized a variety of approaches, including stable and transient expression in plants, plant-derived RNAi, defense response and in planta interaction assays, to characterize the function of MjTTL5, an important effector protein secreted by the root-knot nematode M. javanica. Our results indicate that MjTTL5 can interact specifically with the host ferredoxin:thioredoxin reductase catalytic subunit protein (AtFTRc) to suppress plant defense, thereby allowing the nematode to have a successful infection. This study provides new evidence for a role of RKN-secreted effector proteins in host defense suppression.

Technical Abstract: Oxidative burst is a hallmark event of the pathogen-associated molecular pattern (PAMP) triggered immunity (PTI), which is the first line of plant defense mechanisms, but it remains unclear how nematodes can overcome this defense mechanism. In this study, we show that plant-parasitic nematode Meloidogyne javanica has evolved a novel effector MjTTL5 that is critical for the suppression of host basal defense responses. Transgenic Arabidopsis lines expressing MjTTL5 were found to be significantly more susceptible to M. javanica infection than wild-type control plants, and vice versa, in planta silencing of MjTTL5 through RNAi-technology substantially increased plant resistance to M. javanica. Consistent with these findings, we show that MjTTL5 can specifically suppress plant PTI responses including the expression of defense-related genes and the production of reactive oxygen species (ROS). We further demonstrate that MjTTL5 interacts specifically with the Arabidopsis ferredoxin:thioredoxin reductase catalytic subunit (AtFTRc), a key component of host antioxidant system. Significantly, we show that the expression of MjTTL5 could drastically increase the plant ROS scavenging activity. Our results show that the host ROS-scavenge system can be exploited cunningly by M. javanica, revealing a novel mechanism utilized by plant-parasitic nematodes to subjugate plant innate immunity and thereby promoting plant parasitism.