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.

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

“…Mature females of T. semipenetrans in Turkey were compared with those in a previous study (Table 3). The PVSC of the Turkish population was larger than that documented by Park et al (2009) (1.42-7.86 lm 1.31-5.24 lm versus1.8-7.1 lm), while the PVSW was similar (11.52-16.60 lm versus 10.5-14.4 lm) to that described by Rashidifard et al (2015). The cuticle thickness of T. semipenetrans in the present study was thicker than that documented by Inserra et al (1988) (4.08-10.55 lm versus 3.9-9.2 lm).…”

“…The cuticle had not formed rings and the tail had a rounded terminus. The body length/maximum body width (a) was high compared with that in Park et al (2009), and body length/oesophageal length (b) was lower compared than that in Rashidifard et al (2015). The differentiation among species in the present study may be related to populations under different soil ecological conditions.…”

Development and Evaluation of Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Tylenchulus semipenetrans Using DNA Extracted from Soil

“…Furthermore, for PCR-based detection methods, DNA extraction is performed using individual nematode from a nematode suspension (Liu et al, 2011; Maafi et al, 2012; Rashidifard et al, 2015). The operational procedures of these methods are time-consuming, and require J2 of T. semipenetrans to be distinguished from the nematode mixture as well, which is not a simple and rapid diagnosis for T. semipenetrans .…”

“…Traditional method for T. semipenetrans identification depends mainly on morphological observation of mature females, males and second-stage juveniles (J2) by microscopy (Inserra et al, 1988; Rashidifard et al, 2015), which is time-consuming, laborious and requires taxonomic expertise. In particular, it is difficult to distinguish J2 of T. semipenetrans from many other plant-parasitic and non-plant-parasitic nematode species microscopically.…”

“…Detecting the presence of T. semipenetrans in the soil is essential for both the diagnosis of the disease and many cropping decisions, especially for establishing a citrus nursery site (Liu et al, 2011). Although PCR-based methods described above identified J2 of T. semipenetrans , they were designed to use DNA extracted from isolated individuals that requires a long operation time and experienced personnel (Liu et al, 2011; Maafi et al, 2012; Rashidifard et al, 2015). Hence, a rapid, simple and time-saving nematode extraction method is also needed for quick diagnostic of T. semipenetrans .…”