ARS | Publication request: Inheritance of Ica Bunsi-Derived Resistance to White Mold in a Navy X Pinto Bean Cross

Submitted to: Crop Science
Publication Acceptance Date: February 2, 2004
Publication Date: September 1, 2004
Citation: Miklas, P.N., Hauf, D., Henson, R., Grafton, K.F. 2004. Inheritance Of Ica Bunsi-Derived Resistance To White Mold In A Navy X Pinto Bean Cross. Crop Science. 44:1584-1588.

Interpretive Summary: White mold (WM) disease is a major concern to dry bean growers across the United States. A survey of mostly pinto and navy bean growers in North Dakota and Minnesota found that respondents ranked white mold as the most serious disease problem, with fungicides used on 33% of the acreage in an attempt to control the disease. Other reports suggest losses for great northern bean averaging 30% in Nebraska with individual field losses as high as 92%. Genetic resistance can be effective for disease control but is not available in pinto bean. We conducted an inheritance study to look at the feasibility of transferring white mold resistance from navy bean to pinto bean. Resistance was successfully transferred from navy bean to pinto bean using conventional hybridization and selection. Inheritance of the resistance to WM was quite complex. Both disease avoidance due to modified plant architecture and physiological resistance contributed to overall field resistance. Two pinto bean lines with promising field resistance, high yield, and acceptable maturity were obtained and will help to combat this major disease problem of pinto bean across the United States.

Technical Abstract: Pinto beans (Phaseolus vulgaris L.) are extremely susceptible to white mold disease caused by Sclerotinia sclerotiorum (Lib.) de Bary. Breeding pinto beans with resistance to white mold is difficult due to the paucity of resistance sources in a related background. Our objectives were to determine inheritance of Bunsi-derived resistance in a cross with pinto bean, determine association of the resistance with disease avoidance, and identify pinto beans with Bunsi-derived resistance. White mold resistance of 85 F5:8 recombinant inbred lines (RIL) from the cross 'Aztec'/ND88-106-04 was characterized in field nurseries planted in North Dakota and Washington during 2001 and 2002. Disease severity for Aztec and ND88-106-04 across environments was 6.9 and 2.5, respectively, compared to 4.6 for Bunsi. Reduced lodging and late maturity contributed to disease avoidance. The RILs with increased green stem at harvest maturity, similar to the ND88-106-04 parent, also exhibited less disease. Normal distribution and moderate heritability (Hns = 56% and 36% for WA and ND environments, respectively) for disease score indicated resistance was influenced by environment and likely conditioned by multiple genes. Although quantitatively inherited, Bunsi-derived resistance to white mold was present in a few RILs with high yield potential and pinto seed type.