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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #320532

Research Project: Genetic Enhancement of Common Bean Using Exotic Germplasm for Biotic and Abiotic Stress Tolerance

Location: Tropical Crops and Germplasm Research

Title: Isolates of Rhizoctonia solani can produce both web blight and root rot symptoms in common bean (Phaseolus vulgaris L.)

Author
item Valentin-torres, Suheidy - University Of Puerto Rico
item Vargas, Maria - University Of Puerto Rico
item Godoy-luts, Graciela - Dominican Institute For Agricultural And Forestry Research (IDIAF)
item Porch, Timothy - Tim
item Beaver, James - University Of Puerto Rico

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/29/2016
Publication Date: 4/21/2016
Citation: Valentin-Torres, S., Vargas, M.M., Godoy-Luts, G., Porch, T.G., Beaver, J.S. 2016. Isolates of Rhizoctonia solani can produce both web blight and root rot symptoms in common bean (Phaseolus vulgaris L.). Plant Disease. http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-11-15-1270-RE.

Interpretive Summary: Rhizoctonia solani (Rs) is an important pathogen in the tropics, causing web blight (WB), and a widespread soil-borne root rot (RR) pathogen of common bean (Phaseolus vulgaris) worldwide. This pathogen is classified into 14 groups, Anastomosis Groups (AG). Some AGs have been reported to cause web blight of the above-ground structures of the plant, while other AGs are associated with root rots. There is limited information, however, concerning the ability of specific AGs to cause both diseases in common bean. Nine Rs isolates, collected from both roots and leaves of common bean in Puerto Rico, were used to evaluate the response of 12 common bean genotypes to WB and to RR in the greenhouse. All Rs isolates were able to induce both RR and WB symptoms. Root rot readings were generally more severe than the WB readings. The RR isolate RR1 (AG 4) produced the most severe RR scores. A few bean lines had mean RR scores = 4.4 for specific Rs isolates, on a 1 to 9 scale with 1 indicating resistance. However, all of the bean lines had mean RR scores = 5.0 when inoculated with the AG 4 isolates RR1, RR2 and RR3. Significant line by isolate interactions were observed for the WB and RR inoculations for the three planting dates, suggesting a differential response of the common bean lines to the pathogen. This genotypic interaction may require bean breeders and pathologists to monitor the virulence patterns of Rs in specific growing environments, while the compatibility of specific Rs isolates to both aerial and root tissue needs to be considered for disease control strategies.

Technical Abstract: Rhizoctonia solani Kühn (Rs) is an important pathogen in the tropics, causing web blight (WB), and a widespread soil-borne root rot (RR) pathogen of common bean (Phaseolus vulgaris L.) worldwide. This pathogen is a species complex classified into 14 anastomosis groups (AG). Some AGs have been reported to cause web blight of the above-ground structures of the plant, while other AGs are associated with root rots. There is limited information, however, concerning the ability of specific AGs to cause both diseases in common bean. Nine R. solani isolates, collected from both roots and leaves of common bean in Puerto Rico, were used to evaluate the response of 12 common bean genotypes to WB inoculated using a detached-leaf method, and to RR inoculated using a solution suspension of R. solani mycelia in the greenhouse. All Rs isolates were able to induce both RR and WB symptoms. Root rot readings were generally more severe than the WB readings. The RR isolate RR1 (AG 4) produced the most severe RR scores. A few bean lines had mean RR scores = 4.4 for specific Rs isolates. However, all of the bean lines had mean RR scores = 5.0 when inoculated with the AG 4 isolates RR1, RR2 and RR3. Significant line by isolate interactions were observed for the WB and RR inoculations for the three planting dates, suggesting a differential response of the common bean lines to the pathogen. This genotypic interaction may require bean breeders and pathologists to monitor the virulence patterns of R. solani in specific growing environments, while the compatibility of specific R. solani isolates to both aerial and root tissue needs to be considered for disease control strategies.