Venturia inaequalis un Venturia pyrina populācijas daudzveidības raksturojums Latvijā: promocijas darba kopsavilkums zinātnes doktora grāda (Ph.D.) iegūšanai lauksaimniecības, meža un veterinārās zinātnēs = Characterization of population diversity of Venturia inaequalis and Venturia pyrina in Latvia: Summary of the doctoral thesis for the doctoral degree of science (Ph.D.) in agriculture, forestry and veterinary sciences

The scientific work was developed between 2013 and 2022 at APP LLU Institute of Horticulture. The aim: to describe the population diversity of local V. inaequalis and V. pyrina and determine the composition of V. inaequalis races in Latvia. The tasks of research: (1) characterize the diversity of the populations of V. inaequalis and V. pyrina in Latvia, (2) characterize the virulence of V. inaequalis isolates and determine the resistance of apple genotypes in vitro, (3) characterize the virulence of V. pyrina isolates and determine the resistance of pear genotypes under in vitro conditions, (4) determine the composition of V. inaequalis races in Latvia using race differentiating Malus genotypes in field conditions. Novelty of research: (1) for the first time, morphological characterisation of Latvian populations of apple scab causal agent V. inaequalis and pear scab causal agent V. pyrina have been performed, as well as the characterisation of genetic diversity of Latvian populations of apple scab causal agent V. inaequalis using 12 microsatellite (SSR) markers; (2) characterisation of virulence of V. inaequalis and V. pyrina isolates performed for the first time, with determination of the resistance of apple and pear genotypes using leaves and newly developed fruit in vitro; (3) for the first time, the composition of V. inaequalis races in Latvia has been determined by using Malus genotypes for discrimination. Research hypothesis: the populations of the causal agents of apple and pear scab V. inaequalis and V. pyrina in Latvia are diverse, and several V. inaequalis races are present in Latvia. Topicality of research: identifying the race composition and characterizing the diversity of the pathogen populations would allow prediction of increased pathogen aggression and the formation of new races, and assist in the evaluation of breeding material. Structure of the Doctoral Thesis: introduction, literature review, materials and methods, results and discussion, conclusions, reference list and annexes. Introduction describes the justification for the thesis, formulates the purpose and tasks of the work, justifies the novelty of the study, and provides a hypothesis. Includes a list of the author’s publications related to the topic of the thesis. The literature review is composed of 7 sub-chapters, which summarise information on apple and pear growing and the most significant diseases of the two species, the importance and prevalence of scab, the diversity and variability of scab causal agents, as well as the impact of agroecological factors on the development and spread of these pathogens, and the possibility of controlling pathogens within an integrated plant protection system. Materials and methods include 5 sub-chapters which contain information about the collection and development of scab causal agent isolates, the methodology for characterising population diversity using pathogen morphology, and using microsatellite (SSR) markers to characterise the genetic diversity of the population, description of the establishment of in vitro trials for the determination of scab agent virulence and host plant resistance, the establishment of a plantation of Malus genotypes for V. inaequalis scab race differentiation, and description of observation methods, meteorological conditions and statistical analysis methods.