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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Plant, Soil and Nutrition Research » Research » Publications at this Location » Publication #346569
Title: Comparison of phenotyping methods for resistance to stem rot and aggregated sheath spot in rice

Author
item ROSAS, JUAN - College Of Agriculture
item MARTHEZ, SEBASTIAN - Universidad Ort Uruguay
item BONNECARRERE, VICTORIA - Universidad Ort Uruguay
item PEREZDE VIDA, FERNANDO - Ministerio De Ganadería, Agricultura Y Pesca (MGAP)
item BLANCO, PEDRO - Ministerio De Agricultura
item MALOSETTI, MARCOS - University Of Wageningen
item Jannink, Jean-Luc
item GUTIERREZ, LUCA - Universidad Del La Republica

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2016
Publication Date: 8/1/2016
Citation: Rosas, J., Marthez, S., Bonnecarrere, V., Perezde Vida, F., Blanco, P., Malosetti, M., Jannink, J., Gutierrez, L. 2016. Comparison of phenotyping methods for resistance to stem rot and aggregated sheath spot in rice. Crop Science. 56:1619-1627.

Interpretive Summary: Stem and sheath diseases caused by Sclerotium oryzae (SCL) and Rhizoctonia oryzae-sativae (ROS) can severely reduce rice (Oryza sativa L.) yield and grain quality. Genetic resistance is the best strategy to control them. Phenotypic selection for resistance is hampered by heterogeneous distribution of the inoculum in the soil that generates high environmental variability and decreases genetic gain. To have higher selection accuracy it is necessary to develop phenotyping methods with high repeatability and discriminative power. Greenhouse methods have been reported for Rhizoctonia solani Kühn, a more invasive pathogen than SCL and ROS, and for SCL, but no such methods are reported for ROS. Our study compared five inoculation methods for SCL and ROS to identify the more discriminant and repeatable method and to apply it for high-throughput phenotyping of hundreds of rice lines. A method that used an agar disc with growing mycelium attached to the base of stems was found to have the best balance between discrimination among genotypes and variability among replicates of the same genotype for both pathogens. This method was used in five greenhouse experiments for phenotyping resistance to SCL and ROS in a population of 641 rice advanced breeding lines. Heritabilities of resistance ranged from 0.36 to 0.71 in these experiments. These findings have a direct application in screening for resistance of rice to SCL and ROS, and in mapping loci associated to disease resistance.

Technical Abstract: Stem and sheath diseases caused by Sclerotium oryzae Cattaneo (SCL) and Rhizoctonia oryzae-sativae Sawada Mordue (ROS) can severely reduce rice (Oryza sativa L.) yield and grain quality. Genetic resistance is the best strategy to control them. Phenotypic selection for resistance is hampered due to a heterogeneous distribution of the inoculum in the soil that generates high environmental variability and decreases genetic gain. To have higher selection accuracy it is necessary to develop phenotyping methods with high repeatability and discriminative power. Comparison of greenhouse methods have been reported for Rhizoctonia solani Kühn, a more invasive pathogen than SCL and ROS, and for SCL, but no such comparisons are reported for ROS. Our study compares five inoculation methods for SCL and ROS to identify the more discriminant and repeatable method and to apply it for high-throughput phenotyping of hundreds of rice lines. A method that uses an agar disc with growing mycelium attached to the base of stems was found to have the best balance between discrimination among genotypes and variability among replicates of the same genotype for both pathogens. This method was used in five greenhouse experiments for phenotyping resistance to SCL and ROS in a population of 641 rice advanced breeding lines. Heritabilities of resistance ranged from 0.36 to 0.71 in these experiments. These findings have a direct application in screening for resistance of rice to SCL and ROS, and in high-throughput phenotyping for mapping loci associated to disease resistance.