Effect of the biopesticide Novoсhizol on the expression of defense genes during wheat infection with stem rust Puccinia graminis f. sp. tritici.

Stem rust, caused by the fungus Puccinia graminis f. sp. tritici (Pgt), is a harmful disease affecting grain crops. The traditional way to combat this and other infectious plant diseases is to use chemical pesticides. Biopesticides, as well as plant disease resistance inducers - in particular those based on chitosan, a derivative of chitin - are increasingly being considered as an effective and safe alternative. Recently, a globular form of chitosan, Novochizol, has been developed, which has a number of advantages and has shown its effectiveness in preliminary field and laboratory experiments. However, there are no works devoted to the effect of this preparation on the expression of defense genes. Therefore, the aim of this work was to search for genes involved in the response of common wheat (Triticum aestivum L.) to stem rust infection and to evaluate the effect of Novochizol treatment on their transcription during the infection process. The wheat line ISr6-Ra with the stem rust resistance gene Sr6 and two Pgt isolates - an avirulent one, Avr6, and a virulent one, vr6 - were used as a model, allowing us to compare the effects of Novochizol depending on the genetic compatibility in the plant-pathogen pathosystem. To analyze the transcription level of defense genes, leaf material was collected at different time points from 3 to 144 h after inoculation of plants with the pathogen. Quantitative PCR analysis showed an increase in the transcription levels of the CERK1, PR3, PR4, PR5, PR6 and PR9 genes in plants treated with Novochizol and infected with various Pgt isolates compared to untreated infected plants. Pgt isolate Avr6 induced the highest expression of some defense genes (primarily CERK1), which is consistent with the phytopathology data showing the maximum degree of resistance (IT1) to stem rust in Novochizol-treated plants with a combination of Sr6-Avr6 genes. The data obtained confirm that one of the optimal strategies for increasing the resistance of grain crops to fungal pathogens is a combination of selection for specific resistance genes with the use of biological control agents.