|Porch, Timothy - Tim|
Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Research notes
Publication Acceptance Date: 3/20/2007
Publication Date: 3/30/2007
Citation: Zapata, M., Beaver, J., Porch, T.G. 2007. Foliage, pod and internal seed infection of selected common bean lines when inoculated with two strains of Xanthomonas axonopodis pv. phaseoli. Bean Improvement Cooperative Annual Report 50:117-118. Interpretive Summary: Common bacterial blight (CBB), caused by Xanthomonas axonopodis pv. phaseoli (Xap), is an important foliar and seed-borne disease of common bean (Phaseolus vulgaris L.) grown in tropical, subtropical and temperate areas. In this study, common bean resistance to CBB was studied in beans under consideration for public release. In order to select for the most resistant bean lines, different parts of the plant were inoculated using two different strains of the bacteria. The bean lines varied in their resistance to the bacteria and several lines were identified with elevated levels of resistance. The plants generally reacted similarly to the two different strains of bacteria, but there were significant differences in the infection of internal seed tissues between the two strains. Several high-yielding, white-seeded bean lines were identified with CBB resistance that are being considered for release as varieties. Because of the limited number of varieties with high levels of CBB resistance, these lines may play an important role in increasing yield and quality, in CBB prevalent growing areas, in the small white market classes.
Technical Abstract: Common bacterial blight (CBB) is an important foliar and seed-borne disease of common bean (Phaseolus vulgaris L.) grown in tropical, subtropical and temperate areas caused by Xanthomonas axonopodis pv. phaseoli (Xap). In this study, the resistance to CBB was evaluated in advanced breeding lines using both leaf and pod inoculation methods and two strains from Puerto Rico, Xap 484A and Xap 3353. Leaf, pod, and internal seed infection were then evaluated in eight susceptible and eight resistant lines. No significant difference in virulence between the two bacterial strains was detected when inoculated on leaves and pods, however, a significant difference in the ability of the strains to infect internal seed tissues was observed. Internal seed infection was detected only when pods were inoculated with Xap 484-A,and not with Xap 3353, and the level of seed infection on susceptible lines ranged from 16.6 to 100.0%. All of the breeding lines with resistant pods were also resistant to internal seed infection for both strains. Thus, survival of the strains under natural conditions may differ. Several high-yielding, white-seeded bean breeding lines were identified with CBB resistance.