Nematode-citrus plant interactions: host preference, damage rate and molecular characterization of Citrus root nematode Tylenchulus semipenetrans

Abstract AimsCitrus plants are hosts of numerous plant-parasitic nematodes (PPNs), which are microscopic organisms and hidden enemies for plants. Among the PPNs, the citrus root nematode, Tylenchulus semipenetrans, causes significant damage to citrus plantations in the world. Understanding the citrus nematode population, precise nematode identification, host preference among the citrus species, and damage threshold level are crucially important to control T. semipenetrans. Although some studies have been conducted, minutiae about citrus plant-nematode interactions, nematodes density, and molecular nematode identification have not been well understood. MethodsThis study aimed to reveal nematode identification using molecular and morphological methods, host-nematode interactions, host (citrus species) preference, damage of economic threshold (ET), and economic-injury level (EIL). Therefore, citrus plantations of different provinces located in the Mediterranean region of Turkey were investigated.ResultsITS sequences revealed that samples were infested with the citrus root nematode Tylenchulus semipenetrans. The lowest nematode density was obtained from Mersin (80-second-stage juveniles(J2s)/150g-soil), while the highest density was obtained from Adana (18260-J2s/150g-soil). Out of the 73 samples collected from the Mediterranean region, 21.9% have passed the EIL, while 8.2% are on the ET. Citrus nematode reproduced utmost level on roots of Citrus reticulata, followed by C.sinensis, C.limon, and C.parasidisi, respectively. ConclusionThis study revealed that the Citrus nematode is more common than it was thought and that the population fluctuations change according to the citrus plant species. It is of great importance to investigate the possible genetic changes in nematode populations caused by global warming and its negative impact on citrus yield.