Characterization of Macrophomina species in soybean crops and identification of resistance sources

• Grant number: 24/19389-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Daiana Bampi
• Grantee: Daiana Bampi
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated researchers: Kamila Câmara Correa ; Renan Caldas Umburanas ; Sami Jorge Michereff

Abstract

Brazil is the largest soybean producer in the world, but its productivity can be compromised by pathogens responsible for various diseases. In recent years, Macrophomina phaseolina, the causative agent of charcoal rot, has gained attention. So far, this is the only species of the genus Macrophomina identified in this crop as a disease-causing agent. This study aims to: a) characterize species of Macrophomina in soybean crops across different regions of Brazil; b) evaluate the pathogenicity and aggressiveness of isolates; c) understand whether the increased incidence of charcoal rot is associated with the emergence of new Macrophomina species in the field; d) assess whether infected plants exhibit a higher incidence of the pathogen in seeds compared to healthy plants; e) evaluate the genetic resistance of soybean genotypes developed since the 1960s to Macrophomina phaseolina. Root, stem, and soybean seed samples will be collected from various regions of Brazil during the 2024/2025 and 2025/2026 harvests, and an analysis of disease incidence will be conducted in the main cultivation areas. The characterization of species will be performed through molecular analyses using specific and universal primers. For pathogenicity and aggressiveness assessments, 20 isolates of each reported species of Macrophomina will be evaluated. In the resistance evaluation, 50 soybean cultivars released since the 1960s will be tested. Experiments on pathogenicity, aggressiveness of isolates, and genotype reactions will be carried out in a greenhouse using a completely randomized design with five repetitions. The severity of symptoms will be assessed 30 days after seedling emergence. (AU)