Elucidating the tolerance mechanisms of faba bean (Vicia faba L.) to bean broomrape (Orobanche crenata Forssk.) infested soil

Abstract

Abstract Bean broomrape is one of the most destructive parasitic weeds limiting faba bean production in many Mediterranean and Middle Eastern countries. This study aims to investigate the susceptibility of Faba bean genotypes to Bean Broomrape infestation. A field experiment was conducted to evaluate nine Faba bean cultivars with diverse genetic backgrounds. The tested cultivars were Sakha 1, Misr 3, Mariout 2, Giza 429, Giza 843, Giza 716, Nubaria 1, Nubaria 3, and Wadi 1. Giza 429 had the highest plant (73 cm), and Nubaria 1 had the greatest root fresh weight (39.3 g). Giza 429 produced the highest seed yield (3.2 t/ha) and the lowest Bean Broomrape dry weight (40.3 g/m 2 ). In contrast, Nubaria 1 was the most susceptible, with severe yield reduction (0.87 t/ha) and high infestation (110.4 g/m 2 ). Physio-biochemical analyses revealed that resistant cultivars (Giza 429, Misr 3) had increased antioxidant activity and phenolic content, while showing reduced proline. Tolerant cultivars had larger vascular cylinder diameters, wider xylem vessels, and thicker phloem tissue, which enhances nutrient transport and structural resistance to Bean Broomrape. Susceptible cultivars displayed reduced vascular development and smaller xylem vessel areas. Giza 429 is a promising genetic resource for breeding programs aimed at enhancing tolerance to broomrape. The findings highlight the potential contributions of biochemical defense responses and root anatomical adaptations to tolerance mechanisms in faba bean under O. crenata infestation.