Title: A new common bacterial blight resistance QTL in VAX 1 common bean and interaction of the new QTL, SAP6 and SU91 with bacterial strains Authors
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2014
Publication Date: June 1, 2014
Citation: Viteri, D., Cregan, P.B., Trapp, J., Miklas, P.N., Singh, S. 2014. A new common bacterial blight resistance QTL in VAX 1 common bean and interaction of the new QTL, SAP6 and SU91 with bacterial strains. Crop Science. 54:1598-1608. Interpretive Summary: Common bacterial blight is a serious disease which limits dry edible bean (pinto, black, red kidney, etc.) seed quality and production in the United States and worldwide. Resistance genes provide the best method of control. This research describes the discovery of a new resistance gene in dry bean that will be highly useful for control of common bacterial blight in the future. Because this new resistance gene provides control against multiple strains of the bacteria, plant breeders will want to use it in their breeding programs. This broadly effective resistance gene is the first to be discovered in more than 20 years and will facilitate development of new dry bean cultivars with improved resistance to common bacterial blight disease. Phillip Miklas is the Corresponding Author for this publication as the work was performed by a visiting Ph.D. student in his lab.
Technical Abstract: Common bacterial blight (CBB) is a severe disease in common bean. New resistance QTL should facilitate development of cultivars with high levels of resistance. Our objectives were to (i) identify new resistance QTL in VAX 1 and verify presence in VAX 3, (ii) determine interaction of new QTL with existing SAP6 and SU91 QTL, and (iii) examine interaction of the QTL with less aggressive ARX8 and aggressive Xcp25 bacterial strains. Sixty-one F6:7 recombinant inbred lines (RIL) from ‘Othello’/VAX 1 and 100 RIL from Othello/VAX 3 were screened in the greenhouse. Disease severity of inoculated primary leaves, 1st and 2nd trifoloiolate leaves, and pods, was scored from 1= no symptoms to 9= completely diseased. Genotyping was carried out using single nucleotide polymorphism (SNP) and resistance QTL-linked sequence characterized amplified region (SCAR) markers, SAP6 and SU91. A novel resistance QTL with major effect was detected on Pv11 linkage group in Othello/VAX 1 and verified in Othello/VAX 3. This Pv11 QTL, defined by the closest marker SNP47467, explained 23% phenotypic variance for resistance in primary and 18% in trifoliolate leaves in Othello/VAX 1, and 13% and 22%, respectively, in Othello/VAX 3 to ARX8. The Pv11 QTL named Xa11.4(OV1,OV3) had greater influence against Xcp25, with respective values for variance for resistance explained in primary and trifoliolate leaves of 45% and 51% in Othello/VAX 1 and 26% and 37% in Othello/VAX 3. Conversely, SAP6 was only effective against ARX8 in both populations and surprisingly SU91 was only effective against Xcp25 in Othello/VAX 3. SAP6 was the only QTL to condition resistance in pods. QTL interactions and differential reactions to strains indicate the new Xa11.4OV1,OV3 QTL is critical for breeding for stable and higher levels of foliage resistance to CBB in common bean