Nitrogen fertilizer rate but not form affects the severity of Fusarium wilt in banana

Ryan Orr; Paul G Dennis; Yide Wong; Daniel J Browne; Martha Cooper; Henry W G Birt; Hazel R Lapis-Gaza; Anthony B Pattison; Paul N Nelson

doi:10.3389/fpls.2022.907819

Nitrogen fertilizer rate but not form affects the severity of Fusarium wilt in banana

Front Plant Sci. 2022 Jul 22:13:907819. doi: 10.3389/fpls.2022.907819. eCollection 2022.

Authors

Ryan Orr¹, Paul G Dennis², Yide Wong^{3

4

5}, Daniel J Browne^{3

5}, Martha Cooper^{3

4}, Henry W G Birt^{2

6

7}, Hazel R Lapis-Gaza⁸, Anthony B Pattison⁸, Paul N Nelson¹

Affiliations

¹ College of Science and Engineering, James Cook University, Cairns, QLD, Australia.
² School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD, Australia.
³ Australian Institute of Tropical Health and Medicine (AITHM), James Cook University, Cairns, QLD, Australia.
⁴ Centre for Tropical Bioinformatics and Molecular Biology, James Cook University, Cairns, QLD, Australia.
⁵ Centre for Molecular Therapeutics, James Cook University, Cairns, QLD, Australia.
⁶ Department of Plant Science, The Pennsylvania State University, University Park, PA, United States.
⁷ Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, United States.
⁸ Department of Agriculture and Fisheries, South Johnstone, QLD, Australia.

Abstract

Nitrogen (N) fertilizers are routinely applied to bananas (Musa spp.) to increase production but may exacerbate plant diseases like Fusarium wilt of banana (FWB), which is the most economically important disease. Here, we characterized the effects of N rate and form on banana plant growth, root proteome, bacterial and fungal diversity in the rhizosphere, the concentration of Fusarium oxysporum f.sp. cubense (Foc) in the soil, and the FWB severity. Banana plants (Musa subgroup ABB) were grown under greenhouse conditions in soil with ammonium or nitrate supplemented at five N rates, and with or without inoculation with Foc. The growth of non-inoculated plants was positively correlated with the N rate. In bananas inoculated with Foc, disease severity increased with the N rate, resulting in the Foc-inoculated plant growth being greatest at intermediate N rates. The abundance of Foc in the soil was weakly related to the treatment conditions and was a poor predictor of disease severity. Fungal diversity was consistently affected by Foc inoculation, while bacterial diversity was associated with changes in soil pH resulting from N addition, in particular ammonium. N rate altered the expression of host metabolic pathways associated with carbon fixation, energy usage, amino acid metabolism, and importantly stress response signaling, irrespective of inoculation or N form. Furthermore, in diseased plants, Pathogenesis-related protein 1, a key endpoint for biotic stress response and the salicylic acid defense response to biotrophic pathogens, was negatively correlated with the rate of ammonium fertilizer but not nitrate. As expected, inoculation with Foc altered the expression of a wide range of processes in the banana plant including those of defense and growth. In summary, our results indicate that the severity of FWB was negatively associated with host defenses, which was influenced by N application (particularly ammonium), and shifts in microbial communities associated with ammonium-induced acidification.

Keywords: Fusarium wilt (causal agent Fusarium oxysporum); ammonium; banana; disease triangle; nitrate; nitrogen fertilisation; proteomics; qPCR.