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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #383898
Research Project: Trait Discovery, Genetics, and Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research

Title: Transcriptomic and histological analyses of the response of susceptible and resistant cucumbers to root-knot nematode infection reveal complex resistance via multiple signaling pathways

Author
item LI, XVZHEN - Northwest A&f University
item SUN, YINHUI - Northwest A&f University
item YANG, YUTING - Northwest A&f University
item YANG, XIAOPEI - Northwest A&f University
item XUE, WANYU - Northwest A&f University
item WU, MEIQIAN - Northwest A&f University
item CHEN, PANPAN - Northwest A&f University
item Weng, Yiqun
item CHEN, SHUXIA - Northwest A&f University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2021
Publication Date: 6/14/2021
Citation: Li, X., Sun, Y., Yang, Y., Yang, X., Xue, W., Wu, M., Chen, P., Weng, Y., Chen, S. 2021. Transcriptomic and histological analyses of the response of susceptible and resistant cucumbers to root-knot nematode infection reveal complex resistance via multiple signalling pathways. Frontiers in Plant Science. 12. Article 675429. https://doi.org/10.3389/fpls.2021.675429.
DOI: https://doi.org/10.3389/fpls.2021.675429

Interpretive Summary: The Southern root-knot nematode (SRKN) is a devastating soil-borne disease for cucumber production especially under protected environments or continuous cropping. No resistance against SRKN has been identified in cucumber. However, good resistance has been identified in the cucumber wild relative, African horned melon (CM). In this study, we conducted comparative anatomical studies in a susceptible cucumber line (Q24) and a resistant horned melon line (CM). We found that the resistance in CM was able to significantly reduce penetration numbers of second stage juveniles of the nematode, slow its development in the roots which resulted in fewer galls and smaller giant cells. Comparative transcriptome analysis of Q24 and CM before and after SRKN infection identified differentially expressed genes associated with host resistance in CM. We found that the most enriched genes involved in calcium signaling, salicylic acid/jamonate signaling (JA), as well as auxin/cytokinin signaling pathways. In particular, in CM, genes in the calcium-signaling pathway were upregulated at the early stage of RKN infection; genes for SA/JA synthesis/signal transduction were markedly activated, whereas the IAA/CTK signalling pathway genes were inhibited upon infection. These observations suggested the importance of SA/JA signaling pathways in mediating RKN resistance in CM. This work provides insights into potential mechanisms of RKN resistance in horned melon, which should be useful for exploring this resistance source for cucumber improvement.

Technical Abstract: The root-knot nematode (RKN), Meloidogyne incognita, is a devastating pathogen for cucumber (Cucumis sativus L.) especially in production under protected environments or continuous cropping. No host resistance against RKN has been identified in cucumber. However, high level RKN resistance has been identified in African horned melon, C. metuliferus (CM), a wild relative of C. sativus. In this study, we conducted comparative analysis between the susceptible cucumber inbred line Q24 and a resistant CM accession on phenotypic mechanisms of resistance to RKN in response to RKN infection. We found that, as compared with Q24, the resistance CM was able to significantly reduce penetration numbers of second stage juveniles (J2), slow its development in the roots resulting in fewer galls and smaller giant cells suggesting the presence of host resistance in CM. We conducted comparative analysis of the transcriptomes of Q24 and CM before and after RKN infection, and identified differentially expressed genes (DEGs) associated with host resistance in CM. Functional annotation, gene ontology and pathways enrichment analyses revealed most enriched DEGs in Ca2+ signaling, salicylic acid (SA)/jamonate signaling (JA), as well as auxin (IAA)/cytokinin (CTK) signaling pathways. In particular, in CM, DEGs in the Ca2+ signalling pathway such as those for the calmodulin and calcium-binding proteins were upregulated at the early stage of RKN infection; genes for SA/JA synthesis/signal transduction were markedly activated, whereas the IAA/CTK signalling pathway genes were inhibited upon infection suggesting the importance of SA/JA signalling pathways in mediating RKN resistance in CM. A model was established to explain the different molecular mechanisms on RKN susceptibility in cucumber and resistance to RKN infection in CM.