Reaction of detached leaves from different varieties of sweet orange to inoculation with Xanthomonas citri subsp. citri

Abstract

Citrus genotypes show a broad range of resistance to infection with Xanthomonas citri subsp citri (Xcc), the causal agent of Asiatic citrus canker (ACC). The aim of this study was to evaluate a detached leaf inoculation method to compare nine different citrus genotypes that exhibit varied resistance levels to ACC, and to evaluate infection, colonization and symptom development of the varieties by using Scanning Electron Microscopy (SEM). Inoculation of Xcc in the leaves was carried out by producing injuries with needles. Lesion diameters were measured at 7, 10 and 13 days after inoculation (DAI). The variety Pera IAC was most resistant to the pathogen and had lesions with smaller diameters, while the variety Washington was most susceptible and had the largest lesions, indicating low resistance to Xcc. SEM images were taken from the lesion development, and sections were obtained from the disease lesions in the tested varieties. The most resistant variety, Pera IAC, had smaller stomatal openings and produced greater quantity of foliar exudates, compared with the variety Washington. We hypothesize that the exudates may contain Xcc toxic compounds and thus may be a defense mechanism against infection by Xcc, but further research is required to establish any antibiotic effects of the exudates against citrus canker.

Combination of Potassium Phosphite and Reduced Doses of Fungicides Encourages Protection against Phytophthora infestans in Potatoes

“…This suggests that results derived from in vivo bioassays can be generalized to greenhouse assays. Detached leaf assay is a fast, cost-effective and high-throughput screening approach which is less dependent on space limitations compared to the greenhouse or field screening methods [44,45]. In this context, Foolad et al [46] revealed correspon-dence relationship between detached leaf results and those from field and greenhouse screenings for late blight resistance.…”

Differences in Leaf Morphological Parameters of Pear (Pyrus communis L.) Based on Their Susceptibility to European Pear Rust Caused by Gymnosporangium sabinae (Dicks.) Oerst.

“…Plant stomata have many functions, but they can also be an indicator of pathogen resistance. Several studies have shown that susceptible cultivars have a higher stomatal density [22][23][24]. The interaction between pathogen and plant stomata is still being discussed, however.…”

<b>Zero-inflated beta regression model for leaf citrus canker incidence in orange genotypes grafted onto different rootstocks

“…citri. (Gonçalves-Zuliani et al, 2016). This disease does not have control, the recommendation is the elimination of infected plants, however, some studies have pointed possible means of control, indicating that in the future the disease will be controlled (Sauer et al, 2015).…”