DNA Damage Triggers the Activation of Immune Response to Viral Pathogens via Salicylic Acid in Plants.

Plants are challenged by various pathogens throughout their lives, such as bacteria, viruses, fungi, and insects; consequently, they have evolved several defense mechanisms. In addition, plants have developed localized and systematic immune responses due to biotic and abiotic stress exposure. Animals are known to activate DNA damage responses (DDRs) and DNA damage sensor immune signals in response to stress, and the process is well studied in animal systems. However, the links between stress perception and immune response through DDRs remain largely unknown in plants. To determine whether DDRs induce plant resistance to pathogens, Arabidopsis plants were treated with bleomycin, a DNA damage-inducing agent, and the replication levels of viral pathogens and growth of bacterial pathogens were determined. We observed that DDR-mediated resistance was specifically activated against viral pathogens, including turnip crinkle virus (TCV). DDR increased the expression level of pathogenesis-related (PR) genes and the total salicylic acid (SA) content and promoted mitogen-activated protein kinase signaling cascades, including the WRKY signaling pathway in Arabidopsis. Transcriptome analysis further revealed that defense- and SA-related genes were upregulated by DDR. The atm-2atr-2 double mutants were susceptible to TCV, indicating that the main DDR signaling pathway sensors play an important role in plant immune responses. In conclusion, DDRs activated basal immune responses to viral pathogens.

Rapid and specific detection of apple chlorotic leaf spot virus in pear by reverse-transcription recombinase polymerase amplification.

Apple chlorotic leaf spot virus (ACLSV) is an important virus infecting fruit trees. It causes serious economic losses in the global production of fruit trees belonging to the genera Prunus and Malus and can be vegetatively transmitted during propagation. In this study, an isothermal reverse transcription-recombinase polymerase amplification (RT-RPA) assay method was developed for detecting ACLSV in pear leaves. A set of RT-RPA primers showed high rapidity, sensitivity, and specificity in ACLSV detection. The RT-RPA assay was performed at a single, constant temperature of 42°C, could be completed in approximately 10 min, and did not exhibit cross-reactivity with other common pear viruses. This RT-RPA assay was 100-fold more sensitive than regular RT-PCR. The optimized RT-RPA assay was further used to detect ACLSV in field-collected pear samples. These advantages make RT-RPA a promising diagnostic tool for determining ACLSV infection in pear certification programs. Keywords: apple chlorotic leaf spot virus; detection; pear; reverse transcription-recombinase polymerase amplification.