Distribution, morphology, seasonal dynamics, and molecular characterization of Tylenchulus semipenetrans from citrus orchards in southern Iran

Abstract

Tylenchulus semipenetrans was identified morphologically from root samples collected from citrus orchards in Shahdad region, southeastern Iran. The number of juveniles and females averaged 648/100 g soil and 65/10 g root, respectively, in infected samples. Monitoring these orchards for two years (2012-2013) indicated no significant correlation between soil pH (7.21-7.70) and EC (0.56-1.98) values and populations densities of T. semipenetrans. With respect to seasonal distribution, T. semipenetrans attained the highest density during fall and the lowest in spring. Sequence analysis of the D2-D3 segment of 28S rDNA confirmed this population as T. semipenetrans. Nblast indicates that the sequence from this population differs in only three or five nucleotides from corresponding sequences from T. semipenetrans populations from Korea (FJ969715, FJ060713, and FJ969712), with 99% identity. The phylogenetic position and a table of measurements of this species are provided