Detection of Meloidogyne mayaguensis on guava and papaya in Goias State of Brazil using molecular markers

Detection of Meloidogyne mayaguensis on guava and papaya in Goias State of Brazil using molecular markers Meloidogyne mayaguensis was reported for the first time in the State of Goias (Formosa and Luziania), causing damage in one-year old and 14 year-old commercial guava (Psidium guajava) cv. Paluma orchards. Plants infected by the nematode showed symptoms such as stunted growth, general chlorosis, nutrient deficiency and consequent decline in yield quality and quantity. Severely infested root systems were poorly developed, distorted by small and large multiple galls and devoid of fine roots. Plants of papaya cv. Formosa were cultivated in consortium with guava in the Formosa orchard and presented several galls in the root system, but no. root-knot-nematode secondary symptoms were observed in the aerial part. The production of papaya fruits was high, evidencing tolerance of this cultivar to the nematode. The M2 phenotype (Rm: 0.7, 0.9) was detected for the isoenzyme esterase and M. mayaguensis was identified in both crops and orchards. The analyses with species-specific molecular markers using primers that amplify intergenic regions of the ribosomal DNA and the mitochondrial DNA confirmed the same diagnosis. Surveys carried out in other localities of the farm in Formosa detected the presence of Meloidogyne. e. javanica in low population, corroborating the idea that M. mayaguensis was introduced from the Petrolina nursery with planting materials. In the Luziania orchard the nematode probably occurs naturally, considering the age of plants and the small numbers of infected guavas.