Effect of different pre-inoculation procedures on leaf spotting appearance in adult kiwifruit plants artificially inoculated with Pseudomonas syringae pv. actinidiae
Phytopathology studies most often rely on laboratory, greenhouse or field experiments in which plants are artificially inoculated using a variety of pre-inoculation procedures that aim to improve plant infection success. Concerning the Kiwifruit Bacterial Canker (KBC), whose aetiological agent is the bacterium Pseudomonas syringae pv. actinidiae (Psa), the pre-inoculation procedures most often target leaf tissues, promoting bacterial colonization through natural (e.g., stomata) or artificial openings (e.g., leaf wounds). However, the variability in pre-inoculation methods can influence the infection dynamics, making pathogenicity analysis amongst different research studies very complex. Here, four pre-inoculation procedures were tested in adult kiwifruit plants (Actinidia chinensis var. deliciosa ‘Tomuri’; lignified 15-month-old plants grown in pots) for their effect on leaf spotting appearance at 21 days after inoculation. These procedures consisted of: (i) plant enclosure in a plastic bag (maintained 24 h before and 24 h after inoculation; BAG), (ii) leaf wounding with three superficial cuts (CUTS), (iii) plant maintenance at 5 ℃ for 24 h (COLD) and (iv) a combination of all these procedures (ALL). Plants mock-inoculated with Ringer’s solution were included in the experiment as control. Results showed that BAG was the treatment with highest efficacy in causing appearance of leaf spots, since plants showed 7.1, 15 and 40 times more leaf spots than plants from ALL, CUTS and COLD, respectively. Furthermore, treatments ALL, CUTS and COLD did not appear to be suitable pre-inoculation procedures for promoting KBC foliar symptoms. This study highlights the importance of following precise pre-inoculation procedures in plant artificial inoculation with Actinidia chinensis – Psa, where leaf symptoms appearance is commonly utilized in disease severity analysis.info:eu-repo/semantics/publishedVersio
