Determination of suitable plant tissue and sampling time for reliable detection of plmvd by RT-PCR method

Viroids are the smallest pathogens with no protein-coding properties, made up of a circular single-stranded RNA molecule, 246-401 nt length causing plant diseases. PLMVd is the type member of the Pelamoviroid genus of the Avsunviroidae family. This thesis study aimed to find out the optimal sampling time and tissue in plants infected with PLMVd. The study was conducted on two persimmon plants number TH7 and TH9 with NCBI accession numbers MZ289071 and MZ289070, respectively, which had previously been shown to be infected with PLMVd. Sampling was performed monthly between March 2021 and February 2022, and all available plant tissues were extracted and tested for TRNA using RT-PCR. The study concluded that the most reliable testing organs and times when there is a seasonal limitation are the flower bud, bark, and leaf tissue in April, the flower, leaf, bark, and fruit tissue in May, and the bark, leaf, and fruit tissue in September. It has been concluded that bark, leaf, and fruit tissue samples provide consistent results regardless of season. The independent sample T test was used to estimate the likelihood that the PLMVd concentration in climatic data would yield positive or negative findings and its significance. According to the study results, sampling is recommended between 14.40-20.90 °C, humidity rate 41.40-49.30%, average soil temperature 7.35-11.875 °C, sunshine duration 223.10-345.00 hours, and insolation intensity 223.56-313.33 cal÷cm². It was determined that sampling should be conducted by the viroid's biology, the host's phenological phase, and regional meteorological circumstances.