Differential colonization patterns of Xylella fastidiosa infecting citrus genotypes

Abstract

Xylella fastidiosa is a phytopathogenic bacterium that causes disease in many different crops worldwide. In Brazil, X. fastidiosa subsp. pauca causes citrus variegated chlorosis (CVC), which is a disease responsible for economic losses in the citrus agribusiness. Variable host responses to bacterial colonization and disease development have been observed. This work studies the colonization processes of a pathogenic GFP-labelled X. fastidiosa citrus strain in sweet orange (susceptible) and tangor (resistant) parents and two resulting hybrids that exhibited contrasting responses to CVC. Xylella fastidiosa showed increased populations and movement in the susceptible genotypes, but slower compared to other hosts such as grapevine. Scanning electron microscopy revealed that the predominant pitted stem morphology in citrus makes the bacterial movement difficult. In susceptible genotypes X. fastidiosa can move from the primary to the secondary xylem, whilst it is confined to the primary xylem in resistant plants. Associated with this is an induction of lignification that occurs earlier in the resistant genotypes when in the presence of the pathogen, and represents a genetic mechanism that leads to formation of a physical barrier, impairing bacterial colonization.

Nanowire Arrays as Cell Force Sensors To Investigate Adhesin-Enhanced Holdfast of Single Cell Bacteria and Biofilm Stability

“…60 The authors of this genomic analysis concluded that the high similarity might indicate identical metabolic functions shared by these two strains, which could likely use a common set of genes in plant colonization and pathogenesis, permitting convergence of functional genomic strategies. However, bacterial movement is slower in citrus plants, 61,62 suggesting that, in this case, cell adhesiveness may be 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 20 intrinsically different from X. fastidiosa Temecula 1. In fact, the adhesin function might be strongly related to the pathogen-host interaction, which determines adaptation mechanisms towards the host colonization.…”

Susceptibility ofCitrusspp.,Quercus ilexandVitisspp. toXylella fastidiosastrain CoDiRO

“…In the susceptible sweet orange cv. It can locally multiply around the inoculation point but is unable to systemically invade the plant and to colonise tissues distant from the inoculation point (Niza et al, 2015). All sweet orange cultivars tested so far are susceptible, except Navelina ISA 315, which shows very low bacterial titre (Fadel et al, 2014).…”

“…pauca (Coletta-Filho et al, 2007;Garcia et al, 2012;Niza et al, 2015). However, from the experimental evidence and the known variability in sweet orange-X.…”

“…Caipira, for example, a CVC isolate was shown to multiply and move systemically over time, reaching concentrations that increased from log 4-5 CFU/g of tissue at 1 week to log 5-7 CFU/g at 2-4 months after mechanical inoculation. pauca can be detected in resistant genotypes 2-3 months after inoculation, bacterial populations usually decline after several months (Coletta-Filho et al, 2007;Niza et al, 2015). However, acid lime (Citrus aurantifolia), lemon (Citrus limon), grapefruit (Citrus paradisi), pummelo (Citrus grandis), kumquats, Poncirus trifoliata and most mandarins (Citrus reticulata) and tangors (C. sinensis 9 C. reticulata) are highly tolerant or resistant to this pathogen (Coletta-Filho et al, 2007;Garcia et al, 2012).…”

Nanowire Arrays as Force Sensors with Super‐Resolved Localization Position Detection: Application to Optical Measurement of Bacterial Adhesion Forces

“…The bacterial strain used in our work has been modified to overexpress GFP using a genome‐integrated GFP gene . The autofluorescence spectral range of bacterial cells is usually rather large.…”