Detection and characterization of phytoplasma agents in lucernegrowing areas by molecular methods in Sanlıurfa province andbiochemical changes in the host

Symptoms similar to those caused by phytoplasma (such as small leaves, yellowing, reddening, stunting, witches' broom) have been observed in lucerne, one of the most important forage crops both in Turkey and worldwide, during the last 8 years. This study was conducted on plants showing symptoms of small leaves, yellowing, reddening, stunting, and witches' broom in lucerne fields in Şanlıurfa province between 2018 and 2021. As a result of a series of molecular tests (DNA isolation, DNA sequence, Direct-PCR and Nested-PCR), the factor was found to be 99.92% related to Canditatus Phytoplasma australasia (16SrII-D). In addition, the biochemical changes caused by the agent in the plant physiology were investigated. As a result of the research conducted on nine different parameters; ıt was determined that the chlorophyll and protein contents of infected plants were quite low compared to healthy plants, but the Phenol, Proline, MDA (lipid peroxidase activity), CAT (catalase activity), POX (peroxidase activity) and JA (jasmonic acid) contents were quite high (P≤0.05). It was determined that the SA (salicylic acid) content of infected plants was higher compared to healthy plants, but there was no statistically significant difference (P≤0.05). On the other hand, the ways of transfer of the agent to healthy plants and weed hosts were investigated. In conclusion; Sonchus asper (Prickly donkey lettuce) 98.7%, Convolvulus arvensis (Field creeper) 98.7%, Cuscuta spp. (Dodder) 98.7%, Lolium perenne (English grass) 98.7% and Orobanche (Monster grass) 98.6% were associated with Ca.P.australasia.