Evaluation of soybean genotypes for resistance to three seed borne diseases

Authors: Mengistu, Alemu; WRATHER, ALLEN - University Of Missouri; BOND, JASON - Southern Illinois University; RUPE, JOHN - University Of Arkansas; SHANNON, GROVER - University Of Missouri; NEWMAN, MELVIN - University Of Tennessee; Bellaloui, Nacer; CANADAY, D - University Of Tennessee; Arelli, Prakash; CHEN, PENGUIN - University Of Arkansas; PANTALONE, VINCE - University Of Tennessee

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2011
Publication Date: N/A
Citation: N/A

Interpretive Summary: Three seed-borne diseases namely, Phomopsis seed decay caused by Phomopsis longicolla, purple seed stain caused by Cercospora kukuchii, and charcoal rot caused by Macrophomina phaseolina are economically important seed-borne diseases that affect soybean seed quality. Commercial cultivars marketed as resistant to Phomopsis seed decay, purple seed stain and charcoal rot are not available. Reactions of 143 gentoypes in maturity groups (MG) III, IV and V were evaluated for resistance to these diseases during 2006 to 2008. Based on seed infection, some genotypes were resistant to these pathogens in one, two or in all the three years. Genotypes, DP 3478 (Early MG IV) and RO1-769F (MG V) were resistant and DG4460 was moderately resistant to Phomopsis seed decay in all three years. Genotypes AG3705, FFR3990, DC20300, DC7816, Stoddard and Ozark were resistant to purple seed stain during all three years. A total of 39 genotypes had no seed borne charcoal rot in all the three years. These results indicate that comparisons of seed infection to these diseases among genotypes should be made over several years, or false conclusions about resistance to any of the three diseases may be made if assessment is made for limited period of time. The genotypes identified as having resistance to each or combinations of the seed-borne diseases across the three years could be useful as a source for resistance in improving soybean seed quality.

Technical Abstract: Seed-borne diseases of soybeans caused by Phomopsis longicolla (Phomopsis seed decay), Cercospora kukuchii (purple seed stain), and M. phaseolina (charcoal rot) are economically important seed-borne diseases that affect seed quality. Commercial cultivars marketed as resistant to all the three diseases are not available. Reactions of 27 maturity group (MG) III, 30 early MG IV, 33 late MG IV, and 53 MG V genotypes were evaluated for resistance to these pathogens during 2006 to 2008 in a field that had been in no-till production, not irrigated and naturally infested. There was great variation in seed infection among genotypes and years, indicating the value of screening genotypes over multiple years. Some genotypes were resistant to these pathogens in one, two or in all the three years. Genotypes, DP 3478 (Early MG IV) and RO1-769F (MG V) were resistant and DG4460 was moderately resistant to P. longicolla infection across three years. Genotypes AG3705 and FFR3990 (MG III) and DC20300, DC7816, Stoddard and Ozark (MG V), were resistant to C. kukuchii infection during all three years. Ten genotypes in MG III, eight in early MG IV, seven in late MG IV and 14 in MG V had no seed infection by M. phaseolina in all the three years. These results indicate that comparisons of seed infection to these pathogens among genotypes should be made over several years, or false conclusions about resistance to any of the three pathogens may be made when disease is assessed for limited period of time. The genotypes identified as having resistance to each or combinations of the seed-borne diseases across the three years could be useful as a source for resistance in improving soybean seed quality.