Fouad Mokrini

Diversity of root-lesion nematodes (Pratylenchus spp.) associated with wheat (Triticum aestivum and T. durum) in Morocco

Root-lesion nematodes ( Pratylenchus ) have a worldwide distribution and cause severe production constraints on numerous important crops. During a survey of the wheat-growing area of Morocco, 17 populations of root-lesion nematode were collected. They were identified on the basis of their morphological and morphometric characters, and by molecular methods. Microscopic observations of females and males demonstrated the occurrence of P. penetrans in 13 of the 17 samples; P. thornei and P. pseudocoffeae were detected in four samples from Zaers and a single sample from Settat, respectively. A duplex PCR primer set was used to confirm the presence of P. penetrans while the species-specific forward primer PTHO and the common reverse primer D3B were used for P. thornei . For the remaining populations, the D2-D3 expansion segments of the 28S rRNA gene were amplified and the obtained sequences were compared with those of Pratylenchus species in the GenBank database. This comparison confirmed the morphological identifications and revealed a population of P. pinguicaudatus . The study of the phylogenetic relationship of the Moroccan Pratylenchus populations showed a high similarity (99-100%) between all P. penetrans populations. The population dynamics of six Pratylenchus populations from Morocco were evaluated on carrot disk cultures at 4, 8 and 12 weeks after inoculation, and at 10, 15, 20 and 25°C. The optimum temperature for reproduction of all populations was 20°C. After 8 weeks at this temperature, nematode numbers increased up to 458-fold, 310-fold and 252-fold for the four populations of P. penetrans , the P. thornei and the P. pseudocoffeae population, respectively.

The β-1,4-endoglucanase gene is suitable for the molecular quantification of the root-lesion nematode, Pratylenchus thornei

A real-time quantitative PCR assay was developed for the accurate detection and quantification of the root-lesion nematode, Pratylenchus thornei. A qPCR primer set, including two primers and a probe, was designed based on the sequence of the beta-1,4-endoglucanase gene. The assay was optimised by using the primers with SYBR green I dye and setting the qPCR program to different annealing temperatures ranging from 62 to 69 degrees C. Based on the Ct values, we retained the program with an annealing temperature of 69 degrees C. The specificity of the qPCR assay including the probe was confirmed by the lack of amplification of DNA from 47 populations belonging to 15 other Pratylenchus species and nine isolates from P. thornei. The assay was very sensitive as it was able to detect a single individual of P. thornei, even when mixed with up to 80 individuals of P. penetrans. DNA was extracted from exactly 80 P thornei individuals. A dilution series from this DNA resulted in a standard curve showing a highly significant linearity between the Ct values and the dilution rates (R-2 = 0.98; slope = -3.38; E = 97.6%). The qPCR assay developed in this study proved to be specific and sensitive, thus providing a fast and accurate tool for detection and quantification of this pathogen during research, as well as for diagnostic labs.

Occurrence of the root-knot nematode species in vegetable crops in Souss region of Morocco

Root-knot nematodes ‘Meloidogyne spp’ are the most destructive group of plant parasitic nematodes causeing serious losses in vegetables crops and this damages worsened when crops grown under greenhouses conditions. In this sutdy, the distribution and characterization of root-knot nematode species collected from the Souss region of Morocco where vegetables crops intensively cultivated were determined by using both morphological and molecular tools. Out of the 110 samples collected from different greenhouses 91 (81.7%) were found to be infested with root-knot nematodes. Thirty-seven populations of root-knot nematodes were morphologically identified based on perineal patterns as well as molecularlly using species-specific primers. The obtained results indicated that Meloidogyne javanica and M. incognita were identified in 86.4% and 13.5% of the total populations, respectively. The lowest incidence of root-knot nematodes (64%) was found in Toussous, whereas the highest frequencies of 100% and 90% were detected in Taddart and Biogra, respectively. As the majority of the samples have been infested with Meloidogyne species; this indicates that there is an urgent need to provide farmers with a proper control strategy.

First Report of Hop stunt viroid Infecting Citrus Trees in Morocco

M.Afechtal, National Institute for Agricultural Research INRA, Regional Center of Kénitra, BP 257, Kénitra, Morocco; H.Jamai, National Institute for Agricultural Research INRA, Regional Center of Kénitra, BP 257, Kénitra, Morocco, and Faculty of Sciences, University Ibn Tofail, BP 133, Kénitra, Morocco; F.Mokrini, National Institute for Agricultural Research, Regional Center of Agadir, BP 124, Inezgane, Morocco; A.Essarioui, National Institute for Agricultural Research, Regional Center of Errachidia, Errachidia, Morocco; Z.Faddoul, National Institute for Agricultural Research INRA, Regional Center of Kénitra, BP 257, Kénitra, Morocco, and Faculty of Sciences, University Ibn Tofail, BP 133, Kénitra, Morocco; M.Sbaghi, National Institute for Agricultural Research, Plant Protection Department, BP 415, Rabat, Morocco; and A. A.Dababat, International Maize and Wheat Improvement Center (CIMMYT), Emek, Ankara, Turkey.