Sub‐lethal UV‐C radiation induces callose, hydrogen peroxide and defence‐related gene expression in Arabidopsis thaliana

Abstract

Exposure of plants to UV-C irradiation induces gene expression and cellular responses that are commonly associated with wounding and pathogen defence, and in some cases can lead to increased resistance against pathogen infection. We examined, at a physiological, molecular and biochemical level, the effects of and responses to, sub-lethal UV-C exposure on Arabidopsis plants when irradiated with increasing dosages of UV-C radiation. Following UV-C exposure plants had reduced leaf areas over time, with the severity of reduction increasing with dosage. Severe morphological changes that included leaf glazing, bronzing and curling were found to occur in plants treated with the 1000 J·m(-2) dosage. Extensive damage to the mesophyll was observed, and cell death occurred in both a dosage- and time-dependent manner. Analysis of H₂O₂ activity and the pathogen defence marker genes PR1 and PDF1.2 demonstrated induction of these defence-related responses at each UV-C dosage tested. Interestingly, in response to UV-C irradiation the production of callose (β-1,3-glucan) was identified at all dosages examined. Together, these results show plant responses to UV-C irradiation at much lower doses than have previously been reported, and that there is potential for the use of UV-C as an inducer of plant defence.

Using UV-C radiation and image analysis for fungus control in tomato plants

“…In a similar study, UV-C application was used as a complementary treatment to fungicide applications to reduce significantly the disease severity of B. cinerea (up to 82 %), demonstrating the possibility of combining UV-C with fungicides for improving disease management [11]. The effectiveness of UV-C founded in this study, could be also supported by the fact that it is likely that the reduction of development of new lesions after UV-C treatment observed in our work could be also due to that this light can induce defense in plants [51,52]. In addition, most powdery mildews grow superficial on leaves, making them easier to be reached by UV-C light [25].…”

Genome-wide analysis of expansin superfamily in wild Arachis discloses a stress-responsive expansin-like B gene

“…The notable induction of AraEXLB8 in A. stenosperma leaves in response to UV can be also associated with the general ROS-scavenging and signal transduction pathways that triggered changes in the expression of some genes, as expansins, and in the production of secondary metabolites, as resveratrol, to control numerous biological process, including pathogen defense (Baxter et al 2014; Han et al 2015; Lopes et al 2013), and therefore, contributing to the HR resistance mechanism of A. stenosperma , as previously suggested (Guimaraes et al 2010; Morgante et al 2013). UV irradiation and other physical stresses induce ‘cross-tolerance’ responses that are commonly associated with pathogen defense and reactions to wounding, promoting increased resistance to pathogens (Mintoff et al 2015). …”

Mechanisms of callose deposition in rice regulated by exogenous abscisic acid and its involvement in rice resistance to Nilaparvata lugens Stål (Hemiptera: Delphacidae)

“…Callose deposition can be induced by wounding, pathogen infection, methyl jasmonate treatment and ABA . Callose synthase has been found to be activated by glucosides, polyamines, calcium ions, magnesium ions, manganese ions and ABA, and is induced by insects such as aphids and sublethal UV‐C radiation . Thus, during plant growth and development, callose synthesis and degradation reflect abiotic and biological stress.…”