A comprehensive assessment of sunflower genetic diversity against Macrophomina phaseolina

Abstract

The sunflower is a significant oil crop that can thrive in various environmental conditions. However, due to the changing climate, the pathogen profile has been altered, posing a threat to sunflower production. Among the various threats, charcoal rot, caused by the soil-borne fungus Macrophomina phaseolina (Tassi) Goid, is one of the most significant. This study aimed to assess the resistance of 79 sunflower inbred lines to this pathogen using two inoculation methods (toothpick method and unwounded stem base inoculation) and natural disease occurrence in field trials spanning two years. The results showed that both inoculation methods and natural disease occurrence effectively differentiated between resistant and susceptible inbred lines, with the toothpick method being the most effective. Thirteen inbred lines were resistant, 16 were susceptible, and the others were moderately resistant or susceptible. The study identified four inbred lines (MA SC 2, L 1, Ha 74, and PB 21) as the most resistant, making them important sources for breeding sunflower hybrids resistant to M. phaseolina. Their resistance was confirmed in the second year, highlighting their potential to combat the impact of climate change on sunflower production. This study represents a valuable insight into the biological control of M. phaseolina using sunflower resistant genotypes, especially since resistance findings have been lacking in other plant species.