Reactions of 45 bean lines to bacterial blight (xanthomonas axonopodisphaseoli) isolates from major bean producing area of Tanzania.
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Date
2008
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
Studies were conducted, to screen 45 BC1F5 bean lines for common bacterial blight
(Xanthomonas axonopodis pv. phaseoli L) resistance using bacterial blight isolates
collected from lowland and mid altitude bean growing areas in Tanzania. Infected samples
with common bacterial blight (CBB) symptoms were used to obtain CBB bacterium
isolation in a semi-selective bacterial blight differential (BBD) medium. Isolates in the
growth medium were incubated at 25 - 30°C for 4 days for the normal CBB strain and up
to 6-7 days for its variant “fuscous” strains. Local susceptible check (Canadian wonder)
and resistance check (VAX 6) were used to inoculate 45 F5 bean lines in the field and
screen house experiments. Results from the field experiment, inoculated with Xap isolate
from Morogoro district showed that there were significant differences in reactions (P <
0.05 and P < 0.01) among bean lines evaluated. Five lines; PSO3 - 557 (C) - 15, PSO4 -
120 (A) - 15, PSO4 - 120 (A) - 8, PSO3 - 557 (C) - 12 and PSO3 - 557 (C) - 11 showed
to be highly resistant. From the screen house experiment, line PSO4 - 72 (B) - 4 was
resistant to all isolates. Lines PSO4 - 148 (A) - 11, PSO3 - 585 (A) - 12, PSO3 - 585 (A)
- 21, PSO4 - 148 (A) - 15, PSO3 - 585 (A) - 8, PSO4 - 122 (D) - 5, PSO3 - 557 (C) - 7,
PSO3 - 557 (C) - 11, PSO4 - 122 (D) - 4 and PSO3 - 557 (C) - 2, were resistant to three
isolates hence highly resistant. Twenty six lines were resistant to two or one isolates.
Isolate obtained from Mbeya was more virulent than isolates from Ismani, Mgeta and
Morogoro. From these findings it was concluded that, transferring genes for CBB
resistance in adapted bean varieties was successful since resistant lines were identified
among the BC1F5 lines. Therefore, there is a need for further studies on Xap reaction of
bean breeding materials to different isolates from major bean producing areas in the
country.
Description
Dissertation
Keywords
Common bacterial blight (CBB), Bean lines, Tanzania, 45 bean lines, Xanthomonas axonopodisphaseoli