Molecular detection, virulence, and mycelial compatibility of Macrophomina phaseolina isolates associated with chickpea wilt in Sinaloa and Sonora, Mexico

Abstract

Three Macrophomina species (M. phaseolina, M. pseudophaseolina, and M. euphorbiicola) associated with various crops worldwide have been distinguished to date by DNA sequence analysis; however, no studies have been conducted to identify Macrophomina species occurring on chickpea in Mexico. The aims of this study were to identify Macrophomina isolates associated with chickpea wilt through the use of species-specific primers, as well as to determine their virulence and mycelial compatibility. During the 2019 growing season, 58 Macrophomina isolates were obtained from symptomatic plants collected from 19 chickpea crops distributed in the states of Sinaloa and Sonora, Mexico. The identity of all 58 isolates was determined by PCR using three sets of primers specific to three Macrophomina species (M. phaseolina, M. pseudophaseolina, and M. euphorbiicola). Virulence was determined by inoculating chickpea seedling roots with a mycelial suspension and disease severity was assessed 30 days after inoculation. Molecular detection with species-specific primers indicated that all isolates belong to M. phaseolina, with significant differences found in their virulence. Mycelial compatibility testing showed that there are at least six mycelial compatibility groups of M. phaseolina distributed in chickpea fields in Sinaloa and Sonora. This information will serve as a basis for future studies on the epidemiology and management of the disease caused by M. phaseolina on chickpea in Mexico.