Publications

3867

AbstractIncreasing incidences of phytoplasma infestations in Almond trees warrants the better management approach to prevent yield losses. Disease management rely on identification of the pathogen based on molecular profiling. The present study aimed, to identify the phytoplasma agent in almond trees and to measure the biochemical responses it causes in the host. Direct and Nested PCRs performed using phytoplasma specific primer pairs 16S rRNA, detected the presence of phytoplasma agent in symptomatic trees but not in symptomless trees. Phylogeny based on the sequence analysis revealed that the infecting agent was closely related to ‘Candidatus Phytoplasma phoenicium’ (16SrIX‐B subgroup). Then the study was carried out to determine the responses of physiological and biochemical mechanisms in almond trees infected with phytoplasma. Total chlorophyll and protein contents of infected almond trees were lower compared to healthy control, on the other hand, the levels of catalase and peroxidase activity increased in infected trees. Higher levels of stress‐related metabolites such as proline (20.53–39.23 μmol/g), phenol (3.00–4.44 mg GAE/g), salicylic (94.96–138.22 ng SA/mg protein) and jasmonic acid (965.86–1465.10 ng JA/mg protein) were observed in infected trees compared to asymptomatic trees, respectively in healthy and infected trees. The results showed that the Ca. P. phoenicium, which was detected for the first time in Türkiye, was able to change the physiological and biochemical mechanisms. The pathogenic agent could possess a potential danger in almond production areas. It is crucially important that this agent should be considered in certification programs.

AbstractThe evolution of insect vector‐pathogen relationships has long been of interest in the field of molecular ecology. One system of special relevance, due to its economic impacts, is that between Diaphorina citri and ‘Candidatus Liberibacter asiaticus’ (CLas), the cause of the severe Asian form of huanglongbing. CLas‐positive D. citri are more fecund than their CLas‐negative counterparts, boosting opportunities for pathogens to acquire new vector hosts. The molecular mechanism behind this life‐history shift remains unclear. Here, we found that CLas promoted ovarian development and increased the expression of the vitellogenin receptor (DcVgR) in ovaries. DcVgR RNAi significantly decreased fecundity and CLas titer in ovaries, extended the preoviposition period, shortened the oviposition period and blocked ovarian development. Given their importance in gene regulation, we explored the role of miRNAs in shaping these phenotypes and their molecular triggers. Our results showed that one miRNA, miR‐275, suppressed DcVgR expression by binding to its 3' UTR. Overexpression of miR‐275 knocked down DcVgR expression and CLas titer in ovaries, causing reproductive defects that mimicked DcVgR knockdown phenotypes. We focused, further, on roles of the Juvenile Hormone (JH) pathway in shaping the observed fecundity phenotype, given its known impacts on ovarian development. After CLas infection, this pathway was upregulated, thereby increasing DcVgR expression. From these combined results, we conclude that CLas hijacks the JH signalling pathway and miR‐275, thereby targeting DcVgR to increase D. citri fecundity. These changes simultaneously increase CLas replication, suggesting a pathogen‐vector host mutualism, or a seemingly helpful, but cryptically costly life‐history manipulation.

This survey presents the first precise records of Leucomigus candidatus candidatus (Pallas, 1781) in Romania, confirming thus the presence of this species almost a century after its first and single record. Furthermore, ecology, habitat preference and distribution are discussed. We illustrate this taxon with high quality macro photographs, including the male genitalia with the everted and inflated endophallus. Comparative plates with similar-looking species are provided. New localities from Romania and Republic of Moldova are recorded for Cleonis pigra (Scopoli, 1763) and Cyphocleonus dealbatus (Gmelin, 1790).