Divergent responses of tomato cultivars with resistance to Tomato yellow leaf curl virus to infection by Meloidogyne javanica

Commercial tomatoes are usually complex F1 hybrids with multiple resistances genes 9 from different wild Solanum species. The response of tomato cultivars with resistance to root-knot 10 nematodes (RKN) and Tomato yellow leaf curl virus (TYLCV) to infection by M. javanica was deter- 11 mined in controlled environment and in the field. Four treatments were tested: cultivars with i) 12 RKN resistance alone, ii) RKN and TYLCV resistance (RKN+TYLCV), iii) TYLCV resistance alone, 13 and iv) none (susceptible to the nematode and virus). The RKN resistant plants were highly effective 14 suppressing nematode infection and reproduction both in controlled environment and in the field. 15 The RKN+TYLCV resistant plants were also effective but less (P<0.001) than the RKN plants in con- 16 trolled environment although their resistance levels were significantly reduced in the field. None- 17 theless, the RKN+TYLCV plants supported lower (P<0.001) nematode infection and reproduction 18 than the susceptible control plants. The TYLCV resistant plants reduced (P<0.001) nematode infec- 19 tion and reproduction compared to the susceptible control in controlled environment and in the 20 field. The divergent response of tomato cultivars with resistance to TYLCV to infection by Meloido- 21 gyne javanica was attributed to the genetic background of the cultivars.info:eu-repo/semantics/publishedVersio

Penetration and post-infection development of root-knot nematodes in watermelon

Meloidogyne javanica has showed less reproductive success than M. incognita in watermelon genotypes. This study was conducted to elucidate the low reproduction of M. javanica in watermelon. The post-infection development of M. javanica in watermelon ‘Sugar Baby’ was determined at progressively higher initial population (Pi) levels at two time points during the life cycle. Plants were inoculated with 0, 25, 50, 100, 200, and 300 second-stage juveniles (J2)/plant. The increase in Pi was correlated with the penetration rates (R2= 0.603, p&lt;0.001) and total numbers of nematodes in the root (R2 =0.963, p&lt; 0.001) but there was no correlation between the Pi and the reproduction factor (eggs/plant/Pi). The population in the roots at 26 days post-inoculation (dpi) consisted primarily of third-stage juveniles (J3) with a small presence of J2 and fourth stages, and egg-laying females. The dominance of the J3, when egg-laying females are expected, point to the malfunction of the feeding sites that failed to support nematode development beyond the J3 stage. The similarities in egg-laying females at 26 and 60 dpi imply the disruption of the life cycle. Watermelon compensated for M. javanica parasitism by increasing vine length (19% to 33%) and dry top weight (40%) in comparison with the non-inoculated plants. The area under the vine length progress curve was significantly larger as the Pi progressively increased (R²=0.417, p&lt;0.001). Physiological variation was detected between the M. incognita populations. M. arenaria had less ability to invade watermelon roots than did M. incognita and M. javanica

Resistencia al nematodo Meloidogyne en patrones de tomate a temperaturas del suelo superiores a los 28ºC

El gen Mi en tomate confiere resistencia al nematodo Meloidogyne, aunque su eficacia disminuye a temperaturas superiores a los 28ºC. Para determinar la resistencia relativa de 12 patrones y cultivares de tomate frente a M. arenaria y M. javanica se realizaron ensayos en un invernadero sin control climático donde las plantas estaban sujetas a fluctuaciones diarias de temperatura. En el transcurso de los ensayos, la temperatura del suelo fue superior a 28ºC durante 31 días en el primer ensayo (Exp.1) y durante 20 días en el segundo (Exp. 2). El intervalo de tiempo en que la temperatura se mantuvo por encima de los 28oC osciló entre 0,5 a 6 horas/día en el Exp.1 y entre 0,5 a 7,5 horas/día en Exp. 2. Los patrones Morgan, King Kong y Unifort consistentemente mostraron alta resistencia frente a M. arenaria y M. javanica en ambos experimentos, incluso con picos de temperaturas superiores a 28ºC durante parte del experimento. Los patrones Multifort y Maxifort expresaron menor grado de resistencia que los anteriores bajo las mismas condiciones experimentales. En general, la tasa de multiplicación de M. javanica fue mayor (P<0,05) que la de M. arenaria tanto en los tomates resistentes como en los susceptibles.Postprint (published version

Nematodes fitoparàsits: epidemiologia i control

Des de l'any 1991, el grup de nematologia UPC-IRTA està treballant en l'epidemiologia i el control de dos dels principals nematodes limitants de la producció vegetal: Meloidogyne en hortalisses i Tylenchulus semipenetrans en cítrics. Els estudis en ambdós sistemes agrícoles han estat dissenyats per: 1) determinar la distribució i l'abundància dels nematodes, 2) determinar les espècies presents en les àrees de producció i caracteritzar la capacitat parasitària de les poblacions en hostes seleccionats, 3) determinar la fluctuació de les densitats de població en relació amb els condicionants agroecològics de les àrees de producció, 4) determinar la relació densitat de nematodes - pèrdues de producció i 5) determinar l'eficàcia de mètodes i estratègies de control. Es presenten els resultats aconseguits fins al moment en el sistema Meloidogyne - hortalisses i els objectius dels treballs que actualment duem a terme.Desde el año 1991, el grupo de nematología UPC-IRTA está trabajando en la epidemiología y el control de dos de los principales nematodos limitantes de la producción vegetal: Meloidogyne en hortalizas y Tylenchulus semipenetrans en cítricos. Los estudios realizados en ambos sistemas agrícolas han sido diseñados para: 1) determinar la distribución y abundancia de los nematodos, 2) determinar las especies presentes en las áreas de producción y caracterizar la capacidad parasitaria de las poblaciones en huéspedes seleccionados, 3) determinar la fluctuación de las densidades de población en relación con los condicionantes agroecológicos de las áreas de producción, 4) determinar la relación densidad de nematodos - pérdidas de producción y 5) determinar la eficacia de métodos y estrategias de control. Se presentan los resultados conseguidos hasta el momento en el sistema Meloidogyne - hortalizas y los objetivos de los trabajos que llevamos a cabo actualmente.In 1991 the research group on Nematology from UPC-IRTA started working on the epidemiology and control of two of the most important plant parasitic nematodes that limit plant production: Meloidogyne on vegetables and Tylenchulus semipenetrans on citrus. The studies that have been carried out on both agricultural systems were designed to determine: 1) the distribution and abundance of the nematodes, 2) the species that are present in the production area, and the parasitic capability of nematode populations in selected plant hosts, 3) fluctuation of nematode population densities related to agroecological characteristics of the production areas, 4) the relationship between nematode population densities and yield loss, and 5) efficacy of control methods and strategies to manage them. In this paper we present the main results of the research line on Meloidogyne - vegetables and the objectives of the experiments that we are carrying out at present

Effectiveness and profitability of the mi-resistant tomatoes to control root-knot nematodes

Peer Reviewe

Screening culture filtrates of fungi for activity against Tylenchulus semipenetrans

Postprint (published version

The resistance response of solanum Huaylasense accesion LA1358 to Meloidogyne spp.

Postprint (published version

The Mediterranean biotypes of Tylenchulus semipenetrans in Spanish citrus orchards

Postprint (published version

Effect of 1,3 dichlorpropene and rootstocks alone and in combination on tylenchulus semipenetrants and citrus tree growth in a replant management program

Peer Reviewe

Resistance of Hybrid Citrus Rootstocks to a Mediterranean Biotype of Tylenchulus semipenetrans Cobb

The response of 52 citrus hybrid rootstocks to a Mediterranean biotype of Tylenchulus semipenetrans Cobb was determined in greenhouse tests. Seven selections of the cross ‘Cleopatra’ mandarin [Citrus reshni Hort. x Poncirus trifoliata (L.) Raf], and one of Citrus volkameriana Pasq. x P. trifoliata did not support nematode reproduction and were considered as highly resistant to the citrus nematode. The nematode showed very low infectivity and reproductive potential on seven additional selections of ‘Cleopatra’ mandarin x P. trifoliata, one of ‘King’ mandarin x P. trifoliata, and two C. volkameriana x P. trifoliata. These selections were considered as nematode resistant. All the selections with ‘Troyer’ citrange [Citrus sinensis (L). Osbeck x P. trifoliata (L.) Raf] in their parentage supported nematode reproduction but showed different levels of susceptibility