Ralstonia solanacearum Species Complex: A Quick Diagnostic Guide

Abstract

Ralstonia solanacearum (Smith 1896) Yabuuchi et al. 1996 is ranked second among the top 10 most economically important plant pathogenic bacteria. The soil-borne bacterium affects over 200 plant species worldwide, including economically and nutritionally important crops, such as potato (Solanum tuberosum), tomato (Solanum lycopersicum), and bananas (Musa spp.). R. solanacearum is a species complex, meaning that the species is composed of strains with differential characteristics, including different metabolic requirements, centers of origin, host range, and ideal environmental conditions for infection. Its nature and the fact that it is a species complex can make R. solanacearum a difficult bacterium to work with, especially when lacking experience. Inappropriate isolation or storage of the pathogen can lead to inaccurate diagnostics or misleading conclusions. Thus, the objectives of this diagnostic guide are to provide adequate methods for isolation, storage, and identification and to discuss other relevant aspects related to this important plant pathogenic bacterium.

Characterization of Ralstonia solanacearum Causing Bacterial Wilt Disease of Tomato in Coimbatore District of Tamil Nadu, India

“…Representative isolates highly virulent on tomato as well as tobacco led to death of plants were recorded. However, among all other races the R. solanacearum strains belong to race 1, biovar 3 is considered as most economically important disease in solanaceaous crops worldwide as well as from India which reported to cause wilt disease in tomato, eggplant, chilli, potato and tobacco respectively (Denny, 2006;Kumar et al, 2014;Garcia et al, 2019). This research findings forewarning the future spread of the R. solanacearum strains within Tamil Nadu state particularly for solanaceous vegetables cultivation.…”

“…biovars based on utilization of different carbohydrate media (Hayward, 1964) and four phylotypes based on its geographic origins (Fegan and Prior, 2005). R. solanacearum is widely distributed in tropical, sub-tropical and certain warm temperate countries of the world which causes vascular wilt in a wide range of hosts over 450 plant species and more than 50 families (Garcia et al, 2019). In this current study we characterize the R. solanacearum isolates infecting tomato from the Coimbatore district of Tamil Nadu, India for its pathogenicity, race and biovar nature respectively.…”

Revisiting the source of wilt symptoms: X-ray microcomputed tomography provides direct evidence thatRalstoniabiomass clogs xylem vessels

“…In trial 2, these lesions were more common in the 2 dpi plants inoculated with the high titer of bacteria (10 6 cfu) than the moderate titer (10 4 cfu). Internal lesions on tomato stems are an infrequent symptom of Ralstonia wilt of tomato (García et al 2019). Lesions like these are often pigmented brown, suggesting that they are part of a plant defense response that involves the activity of polyphenolic oxidases (Beckman 1964).…”

“…As a counter-point, the biofilm matrix of Ralstonia is highly fluidal (Dalsing and Allen 2014). A diagnostic sign of bacterial wilt disease is “bacterial streaming”, where a bacterial ooze streams out from cut stems when suspended in water (García et al 2019). Further, Ralstonia biomass exudes with xylem sap when partially wilted tomato plants are de-topped.…”

Induction of Defense Related Enzymes by β-aminobutyric Acid against Ralstonia solanacearum in Resistant and Susceptible Cultivars of Tomato

“…The pathogen is considered to have the potential to be developed as a bioterrorist weapon. Strains of R. solanacearum species complex has been grouped as 5 races, 6 biovars, 4 phylotypes and 20 sequevars (Garcia et al, 2019).…”