Introgression of common bacterial blight (xanthomonas axonopodis pv. phaseoli) resistance to common bean (phaseolus vulgaris L.) adapted to Tanzania facilitated by marker assisted selection
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Date
2012-10-09
Journal Title
Journal ISSN
Volume Title
Publisher
International Scholars Journals
Abstract
Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv phaseoli (Xap) is an important
disease of common bean in Tanzania causing severe damage. This study was carried out to introgress
resistance to CBB to the adapted common bean in Tanzania with the facilitation of molecular markers
along with determining the inheritance and heritability of the disease. Crosses were made between the
adapted parent Kablanketi and the resistant parent Vax 4 and their F1, F2 and the backcrosses to both
parents generated. The phenotypic evaluation was carried out after inoculation with Xap and the
molecular marker was applied on the F2 generations using the SCAR marker SAP 6 linked to a QTL for
CBB resistance. The result shows no significant deviation from the expected 3:1 (χ2 = 0.47; P>0.05) in
the F2 population and 1:1 for the backcross to the susceptible parent. These results that resistance in
Vax 4 to Xap is conditioned by the presence of dominant genes. The moderate heritability of 0.32 was
estimated implying that resistance is conditioned by one major gene which has effects of partial
resistance. There were significant correlation between the phenotypic reaction and molecular marker
screening (resistant QTL) (r = 0.502; p<0.05). This indicates there are greater chances of selecting
resistant individuals using molecular markers which also exhibited resistance under field conditions .
Description
International Journal of Agricultural Sciences
Keywords
Common bacterial blight, Xanthomonas axonopodis pv phaseoli, Tanzania., Marker assisted selection