The Transcriptomic Profile of Watermelon Is Affected by Zinc in the Presence of Fusarium oxysporum f. sp. niveum and Meloidogyne incognita.

Bhabesh Dutta,Tim Coolong,Abolfazl Hajihassani,Brendon K. Myers,Mihir Mandal,Kasmita Karki,Aparna Petkar,Chandrasekar Kousik

doi:10.3390/pathogens10070796

Abstract

Zinc (Zn) accumulation and deficiency affect plant response to pests and diseases differently in varying pathosystems. The concentrations of Zn in plants aid in priming defense signaling pathways and help in enhanced structural defenses against plant pathogens. Studies are lacking on how concentrations of Zn in watermelon plants influence defense against two important soil-borne pathogens: Fusarium oxysporum f. sp. niveum (FON) and southern root-knot nematode (RKN, Meloidogyne incognita). In this study a comparative transcriptomics evaluation of watermelon plants in response to high (1.2 ppm) and low (0.2 ppm) levels of Zn were determined. Differential transcript-level responses differed in watermelon plants when infected with FON or RKN or both under high- and low-Zn treatment regimes in a controlled hydroponics system. Higher numbers of differentially expressed genes (DEGs) were observed in high-Zn-treated than in low-Zn-treated non-inoculated plants, in plants inoculated with FON alone and in plants inoculated with RKN alone. However, in the co-inoculated system, low-Zn treatment had higher DEGs as compared to high-Zn treatment. In addition, most DEGs were significantly enriched in hormone signal transduction and MAPK signaling pathway, suggesting an induction of systemic resistance with high-Zn concentrations. Taken together, this study substantially expands transcriptome data resources and suggests a molecular potential framework for watermelon-Zn interaction in FON and RKN.

Highlights

The Fusarium wilt fungus (Fusarium oxysporum f. sp. niveum, Fusarium oxysporum sp. niveum (FON)) and the rootknot nematode (Meloidogyne incognita (Kofoid and White) Chitwood; RKN) are important soil-borne pathogens causing severe damage in watermelon production throughout the world [1,2,3,4]
differentially expressed genes (DEGs) in high-Zn treated plants inoculated with FON and RKN was upregulated
The one DEG in high-Zn treated plants inoculated with FON and RKN was upregulated

Summary

Introduction

The Fusarium wilt fungus (Fusarium oxysporum f. sp. niveum, FON) and the rootknot nematode (Meloidogyne incognita (Kofoid and White) Chitwood; RKN) are important soil-borne pathogens causing severe damage in watermelon production throughout the world [1,2,3,4]. Niveum, FON) and the rootknot nematode (Meloidogyne incognita (Kofoid and White) Chitwood; RKN) are important soil-borne pathogens causing severe damage in watermelon production throughout the world [1,2,3,4]. FON can infect and induce symptoms in watermelon plants at any growth stage [5]. Symptoms of Fusarium wilt at the seedling stage include seedling dieback and a scorched appearance. Tissue chlorosis and unilateral wilting can be observed after loss of turgor pressure. RKN is an obligatory parasite that induces galls on the infected root system of a susceptible host. Galls disrupt the vascular system of plants making them grow poorly and can lead to plant death under heavy infestation [7,8]

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