Metabolomic Fingerprinting of Potato Cultivars Differing in Susceptibility to Spongospora subterranea f. sp. subterranea Root Infection.

Moleboheng Lekota,Jacquie E Van Der Waals,Kehumile J Modisane,Zeno Apostolides

doi:10.3390/ijms21113788

Moleboheng Lekota, Jacquie E Van Der Waals + Show 2 more

Open Access

https://doi.org/10.3390/ijms21113788

Copy DOI

Abstract

Plants defend themselves from pathogens by producing bioactive defense chemicals. The biochemical mechanisms relating to quantitative resistance of potato to root infection by Spongospora subterranea f. sp. subterranea (Sss) are, however, not understood, and are not efficiently utilized in potato breeding programs. Untargeted metabolomics using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was used to elucidate the biochemical mechanisms of susceptibility to Sss root infection. Potato roots and root exudate metabolic profiles of five tolerant cultivars were compared with those of five susceptible cultivars, following Sss inoculation, to identify tolerance-related metabolites. Comparison of the relative metabolite abundance of tolerant versus susceptible cultivars revealed contrasting responses to Sss infection. Metabolites belonging to amino acids, organic acids, fatty acids, phenolics, and sugars, as well as well-known cell wall thickening compounds were putatively identified and were especially abundant in the tolerant cultivars relative to the susceptible cultivars. Metabolites known to activate plant secondary defense metabolism were significantly increased in the tolerant cultivars compared to susceptible cultivars following Sss inoculation. Root-exuded compounds belonging to the chemical class of phenolics were also found in abundance in the tolerant cultivars compared to susceptible cultivars. This study illustrated that Sss infection of potato roots leads to differential expression of metabolites in tolerant and susceptible potato cultivars.

Highlights

The potato plant (Solanum tuberosum L.) is susceptible to attack by many insects and pathogens
Inoculation of plants with subterranea f. sp. subterranea (Sss) resulted in root zoosporangia development in all 10 cultivars assessed (Table 1), while no infection was observed on the uninoculated controls of the cultivars
Untargeted metabolomics analysis tentatively identified several metabolites related to the infection of potato roots by Sss

Summary

Introduction

The potato plant (Solanum tuberosum L.) is susceptible to attack by many insects and pathogens. Subterranea (Sss), the causal agent of powdery scab in potatoes, is one of the most yield-limiting pathogens of potato [1]. Powdery scab of tubers has long been considered the main disease caused by Sss infection of potato, resulting in a reduction in the quality of harvested tubers. It has recently been shown that the pathogen affects plant growth and tuber yields through infection of the roots [2,3,4,5]. Inoculation of potato plants with Sss reduced the root mass in susceptible cultivars compared to tolerant cultivars in the pot trials [7]. The root infection stages of the pathogen (zoosporangia and root galling) are important, due to effects on plant productivity and because of their contribution to increased soil inoculum for the development of powdery scab (tuber disease) epidemics. Potato roots are susceptible to infection at all stages of development [8]

Objectives

Methods

Results

Discussion

Conclusion