Classification of physiological races of Fusarium oxysporum f. sp. phaseoli in common bean

Abstract

Fusarium wilt, caused by Fusarium oxysporum Schlecht. f. phaseoli Kendrick and Snyder (FOP), is a major disease of common bean, causing large economic losses. Genetic resistance is one of the main mechanisms of pathogen control, and knowledge of the physiological variability is fundamental in breeding for resistant cultivars. Thus, a method of pathogen classification that describes the variability and is useful in plant breeding of isolates from different sources was evaluated by different methodologies. Common bean plants of different sets of differentiating cultivars were inoculated with 25 FOP isolates and 3 controls, totaling 28 isolates evaluated 30 days after inoculation. The variability in the isolates found in this study differs from the results of other authors, who reported a small number of physiological races of the pathogen and disagrees with their evaluation of the races and the evaluation methodology. The proposed approach for binary classification based on a group of 12 differentiating cultivars demonstrated that the variability in pathogenicity of FOP is greater than reported so far. By this methodology, 27 different physiological races of the pathogen were obtained. The methods led to contrasting results, with double race classification in the same isolate. The physiological variability found indicates that the physiological races of the pathogen are not limited to 7 as previously mentioned.

Seedborne Pathogenic Fungi in Common Bean (Phaseolus vulgaris cv. INTA Rojo) in Nicaragua

“…Fusarium species are soil-borne fungi that can cause rot of the root, stem, and fruit or vascular wilt in a wide range of crop plants, and they survive as saprophytes [24]. The wide range of different races contributes to the taxonomic complexity [25,26]. Mycotoxin production by Fusarium spp.…”

Cultural, Morphological and Pathogenic Variability among Fusarium oxysporum f. sp. phaseoli Causing Wilt in French Bean (Phaseolus vulgaris L.)

“…According to Fourie et al [22] parasexuality arises by high mutations which may occur among the isolates. High Heterokaryosis has also been associated with continuous cultivation of the host crop [18]. The growth of the French bean in the study area is through continuous cropping.…”

“…However, in this study most isolates were highly virulent. A study by Francisco et al [18] in Brazil also demonstrated a prevalence of higher difference in pathogenic potential among 25 isolates of F. oxysporum f. sp. phaseoli.…”

IAC Netuno: A new black bean cultivar resistant to anthracnose and Fusarium wilt

“…In general, the results of studies developed by research organizations in recent decades have led to an increase in total production and a decrease in growing area, which shows an expressive increase in yield beginning in the 1984/1985 crop season. A significant part of this result is attributable to some crop management factors, but plant breeding is the largest factor responsible for integrating genetic resistance to diseases and increasing the yield capacity of cultivars (Carbonell et al 2010, Barili et al 2015, Henrique et al 2015, Azevedo et al 2015, Melo et al 2017, Pelegrini et al 2017.…”