Diversity of Meloidogyne incognita populations from cotton and aggressiveness to Gossypium spp. accessions

Abstract

a Programa de P os-Graduac ßão em Fitopatologia, Universidade de Bras ılia, Bras ılia, DF 70910-900; b Embrapa Centro de Recursos Gen eticos e Biotecnologia, Bras ılia, DF 70849-970; c Embrapa Algodão,The root-knot nematode (RKN) Meloidogyne incognita is the main nematode causing losses to the cotton crop in Brazil. In order to implement control strategies within integrated management, an accurate identification of the nematode populations prevailing in the cotton production areas is necessary. This study aimed to assess the genetic variability and aggressiveness of RKN populations from cotton production areas in Bahia state, Brazil. All populations were characterized biochemically and molecularly and identified as M. incognita. RAPD and AFLP markers detected 44% of polymorphic fragments among the 13 populations of this species. The 10 M. incognita populations collected in Bahia presented 33.7% of diversity when compared to each other, and 25% when the population from Barreiras (the most polymorphic) was excluded. This polymorphism increased when populations from other Brazilian states were included. The aggressiveness and virulence among populations from Bahia towards different cotton accessions (susceptible/resistant) was also studied. None of the populations showed virulence against the moderately resistant (Clevewilt 6, Wild Mexican Jack Jones and LA 887) and highly resistant (CIR1348 and M-315 RNR) cultivars. Two M. incognita populations from Barreiras were the most aggressive, reaching reproduction factors of 539 and 218, respectively, in the susceptible cultivar FiberMax 966. The most aggressive population (8) was also the most genetically divergent in phylogenetic analyses. These results demonstrate that diversity of M. incognita populations from cotton farms in Bahia is not related to virulence against resistant accessions, which suggests that cultivars containing one or two resistance genes with good agronomic characteristics could be used in infested commercial areas in Bahia state, Brazil.

Nematicidal Evaluation and Active Compounds Isolation of Aspergillus japonicus ZW1 against Root-Knot Nematodes Meloidogyne incognita

“…Root-knot nematodes (Meloidogyne spp.) are economically important worldwide pathogens causing considerable damage to many crops, including cucumbers, tomatoes, rice [1][2][3][4], and even cotton [5,6]. Meloidogyne incognita is an important species of root-knot nematodes worldwide due to its direct impact on crop yields [7][8][9].…”

Selection of cowpea (Vigna unguiculata [L.] Walp) accessions resistant to root‐knot nematode

“…incognita race 3 was obtained in the western region of Bahia (Brazil) by Lopes et al. (2019) and that of M . javanica in the Region of Integrated Economic Development of the Federal District and Surroundings (RIDE), Brazil (Alves, 2015), and cultures were maintained on tomato ( Solanum lycopersicum L.) plants cv.…”

“…The inoculum of M. incognita race 3 was obtained in the western region of Bahia (Brazil) by Lopes et al (2019) and that…”

Identification methods for root-knot nematode Meloidogyne

“…Otra técnica empleada es AFLP, Fragmentos Polimórficos Amplificados al Azar, en esta técnica se basa en la amplificación por PCR de fragmentos que originados por enzimas de restricción, de esta forma se combinan los fundamentos de las técnicas RFLP y PCR, al igual que RAPD es de herencia dominante y ha sido utilizada ampliamente para caracterizar la diversidad genética de fitopatógenos (Becerra & Paredes, 2000;Mayer et al, 2010;Dos Santos et al 2013;Casanovas et al 2013;Rocha et al 2015). como para analizar la diversidad genética de poblaciones de M. chitwoodi y M. fallax, donde se demostró la presencia de diversos grupos poblacionales de estos nematodos (Fargette et al, 2005), así mismo se ha utilizado esta técnica en combinación con marcadores RAPD, demostrando que la diversidad de poblaciones de M. incognita provenientes de cultivos de algodón en el estado de Bahía no se encuentra relacionada con la virulencia en relación a accesiones resistentes, lo que podría deberse a la presencia de 1 o 2 genes de resistencia en estos cultivares (Lopes et al, 2019) Existen otras técnicas para la identificación molecular de Meloidogyne como la técnica LAMP (Amplificación isotérmica de ADN mediada por asas), que puede amplificar grandes cantidades de ADN con gran precisión, en un tiempo corto y además como es isotérmica puede realizarse a una sola temperatura estable, lo que resulta en que no necesita del uso del termociclador y los productos que derivan de la reacción pueden ser observados a simple vista en tubos de reacción, empleando colorantes de ligación al ADN (Mori & Notomi, 2009). Esta técnica ha sido empleada para amplificar segmentos genéticos como el espacio intergénico IGS2-18S, 5S, ITS del rDNA para la correcta y precisa identificación de M. chitwoodi, M. enterolobii y M. hapla (Niu et al, 2012;Peng et al, 2017).…”