Ektaphelenchusberbericusn. sp. was recovered from soil samples collected in eastern Iran and is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by having female body 512-691 μm long, lip region separated from rest of body by a shallow depression, lips separated and equally sized, 19-22 μm long stylet with wide lumen and lacking knobs or swellings at its base, cuticle with fine, but distinct transverse annuli and three lines in lateral field, excretory pore located at base of metacorpus (with slight variation in position), reproductive system monodelphic-prodelphic with spheroid and fine sperm cells inside spermatheca in some individuals and short post-vulval uterine sac (PUS), rectum and anus vestigial (invisible in few individuals), conical posterior body end (tail), narrowing at mid-point between anus and rounded tail tip, and males lacking. The new species is typologically similar to species belonging to four genera:Devibursaphelenchus,Ektaphelenchoides,EktaphelenchusandSeinura, by a combination of morphological characters,e.g., gross morphology of stylet (lacking knobs or swellings at base), morphology of posterior body end (having short conical tail), PUS length, and having a vestigial anus and rectum in most individuals. In molecular phylogenetic analyses using sequences of the partial small subunit of the ribosomal RNA gene (SSU) and the D2-D3 expansion segments of the large subunit (LSU) ribosomal RNA gene, the new species is close to theEktaphelenchoides/Cryptaphelenchusclade in an inferred SSU tree, and formed a clade withEktaphelenchoidesandDevibursaphelenchusspp. in a D2-D3 LSU tree. Further phylogenetic analyses using full length sequences of the internal transcribed spacer region (ITS) (= ITS1 + 5.8S + ITS2) corroborated results from the SSU and D2-D3 LSU trees, and the multilocus analyses using the combined SSU and LSU data placed the new species in a robustly supported clade withEktaphelenchoides poinariandDevibursaphelenchus lini.

Knowledge of the molecular changes in resistant and susceptible cultivars during nematode attack is essential for developing plant resistance. Increased expression of genes related to the synthesis and signaling of salicylic acid, jasmonic acid, and ethylene is known to induce expression of genes related to defense against plant parasitic nematodes. Here, we inoculated approximately 3000 s-stage juveniles (J2s) of Meloidogyne javanica to moderately resistant and highly susceptible tomato cultivars (ALYSTE F-1 and Dutch Mobil, respectively) to compare the developmental disease stages. The roots of each cultivar were collected daily until 30 days after inoculation (DAI). The roots were stained with acid-fuchsin and dissected under a microscope. The results showed that a few parasitic J2s were converted to J3s in the moderately resistant cultivar at 14 DAI, at which time, the highly susceptible cultivar had the highest number of J3s. Comparison of hormonal pathways in the two cultivars revealed that the expression of genes related to the ethylene pathway in ALYSTE F-1 was more strongly upregulated than in Dutch Mobil at 14 DAI. Moreover, the jasmonic acid pathway in the roots of both cultivars decreased at 14 DAI. The expression of genes related to salicylic acid synthesis and signaling was not significantly different between the two cultivars with regard to their non-inoculated controls, respectively, but ALYSTE F-1 in general showed constitutively higher levels of these genes compared to Dutch Mobil at 14 DAI. These results suggest that constitutive and induced expression of genes related to the salicylic acid pathway and ethylene pathway, respectively, delay the development of M. javanica J2s in ALYSTE F-1.

Pistachio yield is annually reduced due to root-knot nematode infections. In order to evaluate its resistance to Meloidogyne javanica, three domestic pistachio rootstocks, namely, Badami, Ghazvini and Sarakhs, and a wild pistachio, Baneh (Pistacia atlantica subsp. mutica), were selected. Their response to the nematode infection was evaluated based on different plant and nematode indexes, 120 days post-inoculation (dpi). The penetration and development rate of nematode in roots of these four pistachio rootstocks were evaluated at different time points by acid fuchsin staining. Based on the measured indexes, Badami, Ghazvini, Sarakhs, and Baneh rootstocks ranked as susceptible, moderately resistant, moderately resistant, and resistant, respectively. The penetration rate of second-stage nematode juveniles (J2) into four rootstocks was discussed. The first “midstage” or swollen juveniles appeared at 4 dpi but to a lesser extent in Ghazvini, Sarakhs, and Baneh cultivars. The first females were seen in Badami at 21 dpi, in Ghazvini and Sarakhs at 35 dpi, and in Baneh at 45 dpi. Three types of defense responses were distinguished and characterized in the examined pistachio rootstocks: (i) a hypersensitive response (HR)-like reaction in the cortex in Ghazvini, Sarakhs, and Baneh root tips at 4 dpi and 6 dpi; (ii) an HR response, degrading J2 which induce giant cells in the vascular cylinder of all rootstocks, at 6 dpi and 10 dpi; and (iii) an HR response, degrading females and giant cells in the vascular cylinder of all rootstocks at 15 dpi onward. These observations open new fields of study in breeding programs of this crop.

Root-knot nematodes (RKNs) are the most destructive nematode species in main pistachio cultivation areas of Iran, and adversely affect crop quality and yield. So far, Meloidogyne incognita and M. javanica have been reported infecting pistachio. In this study, four populations of M. arenaria were found infecting pistachio in Kerman and Khorasan Razavi provinces. The morphology and morphometrics of the recovered populations closely match the data given for other populations of the species. Molecular characterization of the recovered populations was performed by sequencing three genomic and mitochondrial regions, including D2-D3 of LSU rDNA, COII-16S and Nad5 mtDNA. The D2-D3 sequences had more than 99% identity with many sequences of tropical species. The COII-16S sequences had more than 99% identity with sequences of M. arenaria, M. morocciensis and M. thailandica. The Nad5 sequences had 99.81% identity with some sequences of M. arenaria. The D2-D3 and COII-16S sequences of M. arenaria did not form independent clades in corresponding Bayesian trees, but Nad5 sequences formed a monophyletic group in corresponding phylogeny. Based on this study, M. arenaria is present in Iran’s pistachio gardens, necessitating appropriate management measures.