Pea populations derived from ten crosses were scored by coupling phase linked sequence characterized amplified region (SCAR) markers A001 and A002, and repulsion phase linked SCAR marker A004 for lodging resistance during the F2 generation. The objective of this project was to test the efficiency of implementation of these three SCAR markers in marker-assisted selection (MAS) for lodging resistance in pea breeding. Chi-square tests showed that A001 and A004 followed a two independent gene segregation model in all of the eight populations that segregated for these two markers. In the F3 field trial, the differences between mean lodging score of A001 (DNA band present) and a001 (DNA band absent) classes varied from -0.5 to -0.9 with an average of -0.6, based on a 1 to 9 lodging scale, across the eight populations surveyed. The differences between mean lodging score of a004 (DNA band absent) and A004 (DNA band present) classes varied from -0.4 to -1.1 with an average of -0.7, across the eight populations surveyed. In comparison, when the combination of two markers (A001; a004 vs. a001; A004) was used, lodging score differences varied from -0.7 to -1.5, with an average of -1.0 across the eight populations. T-test results showed that significant differences (P<0.05) in lodging score were observed between A001 and a001 classes in seven out of eight populations, and between A004 and a004 classes in six out of eight populations. Further T-tests showed that significant lodging differences were observed among the four classes of the A001 and A004 marker combination in seven out of eight populations assessed, including differences at P<0.01 level in six populations. The greater differences among marker combination classes than between individual marker classes showed that combining two markers was more effective than use of each marker alone in MAS. The marker combination explained (R2) 19-57% of lodging and 4-43% of plant height variation in the eight populations surveyed. The high temperature and potential nitrogen leaching in the summer of 2003, reduced plant growth and lodging. Under optimal growth conditions, differences in lodging between resistant and susceptible cultivars could have been greater. Five new markers generated by simple sequence repeat (SSR) primers SAD134, SAB81 and SAD141 were identified in the recombinant inbred line (RIL) population derived from MP1401 × Carneval. The markers generated from primers SAD134 and SAB81 explained 12% and 13% of lodging variation in the RILs, respectively. Primer SAD141 produced three markers which explained 19%, 11% and 25% of lodging variation in the RILs, respectively. Linkage analysis showed that none of the three markers derived from primer SAD141 were allelic. The combination of the three markers from primer SAD141 explained 28% of lodging variation. However, utilization of any of these new markers with A001 and A004 did not substantially increase the proportion of lodging variation being explained. Thus, the new markers have limited potential to improve the efficiency of MAS for lodging resistance in pea breeding.

Pea populations derived from ten crosses were scored by coupling phase linked sequence characterized amplified region (SCAR) markers A001 and A002, and repulsion phase linked SCAR marker A004 for lodging resistance during the F2 generation. The objective of this project was to test the efficiency of implementation of these three SCAR markers in marker-assisted selection (MAS) for lodging resistance in pea breeding. Chi-square tests showed that A001 and A004 followed a two independent gene segregation model in all of the eight populations that segregated for these two markers. In the F3 field trial, the differences between mean lodging score of A001 (DNA band present) and a001 (DNA band absent) classes varied from -0.5 to -0.9 with an average of -0.6, based on a 1 to 9 lodging scale, across the eight populations surveyed. The differences between mean lodging score of a004 (DNA band absent) and A004 (DNA band present) classes varied from -0.4 to -1.1 with an average of -0.7, across the eight populations surveyed. In comparison, when the combination of two markers (A001; a004 vs. a001; A004) was used, lodging score differences varied from -0.7 to -1.5, with an average of -1.0 across the eight populations. T-test results showed that significant differences (P<0.05) in lodging score were observed between A001 and a001 classes in seven out of eight populations, and between A004 and a004 classes in six out of eight populations. Further T-tests showed that significant lodging differences were observed among the four classes of the A001 and A004 marker combination in seven out of eight populations assessed, including differences at P<0.01 level in six populations. The greater differences among marker combination classes than between individual marker classes showed that combining two markers was more effective than use of each marker alone in MAS. The marker combination explained (R2) 19-57% of lodging and 4-43% of plant height variation in the eight populations surveyed. The high temperature and potential nitrogen leaching in the summer of 2003, reduced plant growth and lodging. Under optimal growth conditions, differences in lodging between resistant and susceptible cultivars could have been greater. Five new markers generated by simple sequence repeat (SSR) primers SAD134, SAB81 and SAD141 were identified in the recombinant inbred line (RIL) population derived from MP1401 × Carneval. The markers generated from primers SAD134 and SAB81 explained 12% and 13% of lodging variation in the RILs, respectively. Primer SAD141 produced three markers which explained 19%, 11% and 25% of lodging variation in the RILs, respectively. Linkage analysis showed that none of the three markers derived from primer SAD141 were allelic. The combination of the three markers from primer SAD141 explained 28% of lodging variation. However, utilization of any of these new markers with A001 and A004 did not substantially increase the proportion of lodging variation being explained. Thus, the new markers have limited potential to improve the efficiency of MAS for lodging resistance in pea breeding.