A quick and efficient hydroponic potato infection method for evaluating potato resistance and Ralstonia solanacearum virulence

Abstract

BackgroundPotato, the third most important crop worldwide, plays a critical role in human food security. Brown rot, one of the most destructive potato diseases caused by Ralstonia solanacearum, results in huge economic losses every year. A quick, stable, low cost and high throughout method is required to meet the demands of identification of germplasm resistance to bacterial wilt in potato breeding programs.ResultsHere we present a novel R. solanacearum hydroponic infection assay on potato plants grown in vitro. Through testing wilt symptom appearance and bacterial colonization in aerial part of plants, we found that the optimum conditions for in vitro potato infection were using an OD600 0.01 bacterial solution suspended with tap water for infection, broken potato roots and an open container. Infection using R. solanacearum strains with differential degree of aggressivity demonstrated that this infection system is equally efficient as soil-drench inoculation for assessment of R. solanacearum virulence on potato. A small-scale assessment of 32 potato germplasms identified three varieties highly resistant to the pathogen, which indicates this infection system is a useful method for high-throughout screening of potato germplasm for resistance. Furthermore, we demonstrate the utility of a strain carrying luminescence to easily quantify bacterial colonization and the detection of latent infections in hydroponic conditions, which can be efficiently used in potato breeding programs.ConclusionsWe have established a quick and efficient in vitro potato infection system, which may facilitate breeding for new potato cultivars with high resistance to R. solanacearum.

Different epitopes of Ralstonia solanacearum effector RipAW are recognized by two Nicotiana species and trigger immune responses

“…Because R . solanacearum GMI1000 also causes brown rot disease on potato, we used an in vitro potato infection system to investigate whether this deletion affected the pathogen's fitness on potato plants (Wang et al, 2019 ). Similar to the wild‐type strain, the mutant strain caused severe wilting symptoms on potato (Figure S6 c,d).…”

“…For potato explants infection we followed the protocol as described in Wang et al ( 2019 ). Briefly, the roots of 2‐ to 3‐week‐old potato plants grown in liquid MS2 medium were cut with scissors and plants were subsequently transferred into glass jars containing 40 ml of a solution of R .…”

L-Amino Acid Oxidases From Mushrooms Show Antibacterial Activity Against the Phytopathogen Ralstonia solanacearum

“…The experiments were performed in two growing chambers, one with plants for groups (A-C) and the other for groups (D-H). For each time point from 1 to 14 days, the symptoms are expressed as proportion of plants with symptoms for each grade according to Winstead and Kelman (1952): dark green, grade 0 (no symptoms); light green, grade 1 (one leaf wilted); light purple, grade 2 (2-3 leaves wilted); dark purple, grade 3 (all leaves except the tip of the plant wilted); yellow, grade 4 (all leaves and the tip of the plant wilted); orange, grade 5 (plant dead). Within groups, the times at which the distribution of the symptoms differed significantly from the corresponding distribution in the positive control group, are indicated: *p < 0.05 and **p < 0.01 (chi-squared tests).…”

“…After the inoculations, the plants were grown at a 28 • C day temperature, with a 16 h photoperiod at 90 µmol m −2 s −1 photon irradiance, and at a 20 • C night temperature. The severities of the symptoms were evaluated regularly over 14 days, following the numerical grades of Winstead and Kelman (1952): 0 (no symptoms), 1 (one leaf wilted), 2 (2-3 leaves wilted), 3 (all leaves except the tip of the plant wilted), 4 (all leaves and the tip of the plant wilted), and 5 (plant dead).…”

Soluble Concentrate Formulation of Oxalic Acid and N-Acetyl-L-Cysteine: Potential of Use in Controlling Ralstonia solanacearum

“…This species is widespread in the world in tropical and subtropical regions. R. solanacearum causes significant yield losses and about 450 plant species have been recorded as hosts of this pathogen ( Maji andChakrabartty, 2014 andWang et al, 2019). Protection methods and chemical control of R. solanacearum are ineffective.…”