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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #327426
Title: Virulence of Macrophomina phaseolina isolates in common bean (Phaseolus vulgaris) genotypes

Author
item ESTEVES DE JENSEN, C - University Of Puerto Rico
item COLLEY, JULIAN - University Of Puerto Rico
item GONZALEZ, OLGA - University Of Puerto Rico
item Porch, Timothy - Tim
item BEAVER, J - University Of Puerto Rico

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Charcoal rot is an important disease in common bean in the dry and warmer areas of Puerto Rico and in much of the tropics and subtropics worldwide. The virulence of three isolates from Isabela (Mph-ISA-TARS), Juana Diaz (Mph-JD) and Aguadilla (Mph-13) and the reaction to Mph-JD of different common bean genotypes were determined. The pathogen was multiplied in pasteurized rice for 15 days in the dark at room temperature. The inoculum consisted of 3 grams of rice colonized by charcoal rot deposited around the seedlings of six different genotypes. Seven and 21 days after inoculation, the plants were evaluated using the CIAT scale (1-9): 1= no visible disease symptoms and 9 = approximately 50% or more of the hypocotyl and stem tissues covered with lesions and pycnidia. In a separate experiment, isolate Mph-JD was used to inoculate four common bean lines, including BAT 477 used as the resistant and G122 as a susceptible checks. Results showed that virulence varied among the three isolates and the genotypes evaluated differed in their response to the pathogen depending on the isolate. The most virulent isolate was the Mph-JD isolate when compared to the isolates from Isabela and Aguadilla. In two consecutive trials, ‘Mecosta’ (ADP-225) was the most susceptible line and G122 (susceptible check) was not and this reaction was dependent on the isolate inoculated. TARS-MST1 was the most resistant to Mph-ISA-TARS. Consistently, ‘Mecosta’ and ‘Zawadi’ (ADP-106) were susceptible to all 3 isolates and the lesion length was significantly longer than in BAT 477 and G122. Genotypes BAT 477, TARS-LFR1, TARS-MST1 and G122 were similar in disease severity and lesion length at 21 days after inoculation. These results indicated that differences exist in virulence of charcoal rot and that these differences in virulence can be used for screening and improving common bean resistance to charcoal rot.

Technical Abstract: Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid, is an important disease in common beans (Phaseolus vulgaris) in the dry and warmer areas of Puerto Rico and in much of the tropics and subtropics worldwide. The virulence of three isolates from Isabela (Mph-ISA-TARS), Juana Diaz (Mph-JD) and Aguadilla (Mph-13) and the reaction to Mph-JD of different common bean genotypes were determined. The pathogen was multiplied in pasteurized rice for 15 days in the dark at room temperature. The inoculum consisted of 3 grams of rice colonized by Macrophomina phaseolina deposited around the seedlings of six different genotypes. Seven and 21 days after inoculation, the plants were evaluated using the CIAT scale (1-9): 1= no visible disease symptoms and 9 = approximately 50% or more of the hypocotyl and stem tissues covered with lesions and pycnidia. In a separate experiment, isolate Mph-JD was used to inoculate four common bean lines, including BAT 477 used as the resistant and G122 as a susceptible checks. Results showed that virulence varied among the three isolates and the genotypes evaluated differed in their response to the pathogen depending on the isolate. The most virulent isolate was the Mph-JD isolate when compared to the isolates from Isabela and Aguadilla. In two consecutive trials, ‘Mecosta’ (ADP-225) was the most susceptible line and G122 (susceptible check) was not and this reaction was dependent on the isolate inoculated. TARS-MST1 was the most resistant to Mph-ISA-TARS. Consistently, ‘Mecosta’ and ‘Zawadi’ (ADP-106) were susceptible to all 3 isolates and the lesion length was significantly longer than in BAT 477 and G122. Genotypes BAT 477, TARS-LFR1, TARS-MST1 and G122 were similar in disease severity and lesion length at 21 days after inoculation. These results indicated that differences exist in virulence of Macrophomina phaseolina.