Selection for white mold resistance in pinto bean


Teran-Santofimio, Henry Terán-Santofimio. (2008). Selection for white mold resistance in pinto bean. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Selection for white mold resistance in pinto bean
Teran-Santofimio, Henry Terán-Santofimio
Common bean--Disease and pest resistance--Testing Sclerotinia sclerotiorum
Plant Science
White mold (WM) caused by Sclerotinia sclerotiorum (Lib.) de Bary is a devastating disease of common bean (Phaseolus vulgaris L.). Improved germplasm screening and breeding methods are needed to facilitate efforts to increase WM resistance. The objectives of this research were to determine (I) the efficacy of three screening methods (SM) to identify resistance, and (II) the effectiveness of gamete (GS) and recurrent selection (RS) in pyramiding resistance from diverse germplasm. The SM were (i) modified straw-test or cut-stem (CSB), (ii) infected bean flower (IFL), and (iii) infected oat seed (IOS). A 195, ICA Bunsi, Othello, and VCW 54 breeding lines and cultivars were tested using a split plot design with three replicates in 2007 and 2008. The WM disease severity was scored at 16, 23, and 33 days post inoculation (DPI) using a 1 to 9 scale. A novel breeding method, GS was practiced from F{esc}b1{esc}s to F{esc}b4{esc}s in two double-cross populations, Pop I = USPT-WM-1/CORNELL 601//USPT-CBB-1/92BG-7 and Pop II = Chase/I 9365-25//ABL 15/A 195. Thirteen selected F{esc}b1{esc}s.{esc}b5{esc}s breeding lines and parents from each population were tested using a randomized complete block design with three replicates in two greenhouse environments. For RS practiced in the same Pop I and II, only highly resistant plants of F{esc}b1{esc}s-derived families of each population were used to produce cycles 1 (C{esc}b1{esc}s) and 2 (C{esc}b2{esc}s). Thirteen S 2 families from each of C{esc}b1{esc}s and C{esc}b2{esc}s and parents (C{esc}b0{esc}s) of each population were tested as in the GS. Differences between SM and their interactions with years were significant. The IFL and CSB were consistent and correlated positively (r>0.70, P>0.01). VCW 54 had the highest resistance with the lowest WM scores, followed by A 195. WM scores increased with delayed evaluations. Only 1.2% of families from Pop I and 0.9% from Pop II survived GS by F4. An average of 38% gain in WM resistance was obtained in both populations. Eleven breeding lines of Pop I were equal to the best WM resistant parent 92BG-7, while 12 breeding lines of Pop II were equal to the best WM resistant parents A 195 and I 9365-25. Gain from RS in Pop I was 12% and in Pop II 5% from C{esc}b0{esc}s to C{esc}b1{esc}s, but differences between C{esc}b1{esc}s and C{esc}b2{esc}s were not significant (P>0.05).
Thesis (Ph. D., Plant Science)--University of Idaho, December 2008.
Major Professor:
Shree P. Singh.
Defense Date:
December 2008.
Format Original:
xii, 89 leaves ;29 cm.

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