Genetic Characterization and Molecular Mapping Pse-2 Gene for Resistance to Halo Blight in Common Bean

Pseudomonas syringae pv. phaseolicola (Burkholder) Young et al. (Psp) causes halo blight, which is a serious bacterial disease of common bean (Phaseolus vulgaris L.). Several resistance (R) genes have been discovered in host differential cultivar ZAA 12. Our objectives were to further characterize and enable marker-assisted selection (MAS) of the Pse-2 gene in ZAA 12 purported to have broad effect against multiple Psp races. A recombinant inbred population, ZAA 12 × ‘Canadian Wonder’, was challenged by the halo blight pathogen differential set consisting of nine Psp races. The resistance conferred by Pse-2 to races 2, 3, 4, 5, 7, 8, and 9 expanded the effect known for this gene from three to seven races. Segregation in F2 populations confi rmed dominant inheritance for Pse-2 against all races except Race 8. Resistance to Race 8 was recessively inherited and most closely fi t a 7 resistant to 9 susceptible segregation ratio in the F2 generation. Perhaps other genes are segregating that modify the effect of Pse-2 against Race 8. A sequence characterized amplifi ed region (SCAR) marker tightly linked with Pse-2 was generated. The marker was used to integrate Pse-2 to chromosome 10. A survey of lines and cultivars revealed the SCAR will have broad utility for MAS of Pse-2. P.N. Miklas, J. Trapp, and R.C. Larsen. USDA-ARS, Vegetable and Forage Crop Research Unit, 24106 N. Bunn Rd., Prosser, WA 99350; D. Fourie, ARC Grain Crops Institute, Potchefstroom, South Africa; C. Chavarro and M.W. Blair, CIAT, Apartado Aereo 6713, Cali, Columbia; and P. Gepts, Univ. of California, Dep. of Plant Sciences/MS1, 1 Shields Ave., Davis, CA 95616. Received 25 Jan. 2011. *Corresponding author ([email protected]). Abbreviations: BA, BelNeb-RR-1 × A 55; BCMNV, Bean common mosaic necrosis virus; DG, DOR 364 × G 19833; HR, hypersensitive resistance; MAS, marker-assisted selection; PCR, polymerase chain reaction; Psp, Pseudomonas syringae pv. phaseolicola (Burkholder) Young et al.; R, resistance; RAPD, random amplifi ed polymorphic DNA; RH, relative humidity; RIL, recombinant inbred line; S, susceptible; SCAR, sequence characterized amplifi ed region; Z12C, ZAA 12 × Canadian Wonder. Published in Crop Sci. 51:2439–2448 (2011). doi: 10.2135/cropsci2011.01.0046 Published online 19 Aug. 2011. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.