Citrus genotypes inoculated with Xanthomonas citri subsp. citri: a study on disease severity and plant stomatic anatomy

Abstract

Brazilian citrus culture became the world's largest producer of fruit since 2012. However, in all harvests it is noted that there are reports of production losses due to the attack of pathogens, among them, we highlight the citrus canker caused by the Xanthomonas citri subsp. citri bacterium. Among the various control methodologies, studying plant resistance is the method considered most economical and efficient. Many studies claim that the variability in relation to the resistance of citrus cultivars may be related to the morphology of their structures, with stomatal density and stomata anatomy influencing the bacterium's ability to penetrate the plant. Thus, the objective of the present study was to evaluate 16 genotypes of citrus (Citrus spp.) relating the influence of the plant's morphology on the severity levels of the Xanthomonas citri subsp. citri bacterium. For this, we used to analyze the severity of the disease through detached leaves and analyze the morphology of the plant through scanning electron microscopy. From the results obtained, it was observed that both the number of stomata present in the plant and the diameter of its stomatal opening did not influence the levels of resistance to the disease. However, important information regarding the defense mechanisms of the plant against the pathogen was observed, such as the production of exudates, in addition to the classification of the Pera 436 genotype as a material with interesting characteristics of resistance to citrus canker.