Genetic dissection of common bacterial blight resistance in the Andean gene pool of common bean
![UNZA logo.png](https://static.wixstatic.com/media/b134c0_14a843bfeb0b4f24b7f49fbe392847c6~mv2.png/v1/fill/w_67,h_85,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/UNZA%20logo.png)
University of Zambia (UNZA) Lusaka, Zambia
Mr Mwiinga Mulube
KT PhD Scholar
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PhD in Plant Breeding and Seed Systems, University of Zambia, 2022-2025
Supervisors: Dr Kelvin Kamfwa and Professor Paul Gepts (University of California, Davis).
Project objectives
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To determine the incidence and severity of Common Bacterial Blight (CBB) in major bean growing areas of Zambia.
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To identify genomic regions and candidate genes associated with CBB resistance in the Andean Diversity Panel of common bean.
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To Map Quantitative Trait Loci (QTLs) for CBB resistance in an Andean population derived from a cross of the bean varieties Inferno (ADP 631) and Kabulangeti.
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To determine the effectiveness of the CBB major-effect QTLs SU91 and SAP6 against CBB strains in Zambia.
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To evaluate the yield stability and genotype × environment interaction (G×E) of CBB resistant elite lines.
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Progress to date
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A diagnostic survey of CBB incidence and severity was carried out on the main bean growing areas in Zambia (ten districts which account for over 70% of production were targeted). Preliminary results showed a wide distribution of CBB ( 90.6 %) in the production area compared to anthracnose (60%). The level of damage caused by CBB (60.3 %) was also higher than for ANT (38. 8%). Farmers were asked about their source of seed (CBB is mainly transmitted through seed): 73.3 of the farmers interviewed obtained their seed from agro-dealers, and the remainder reused saved seed.
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A study was undertaken to identify genomic regions and candidate genes associated with CBB resistance in the Andean Diversity Panel (ADP, a potential source of resistance). 400 ADP lines were screened for CBB resistance in greenhouse conditions and scored using the CIAT severity scale (1-9).GWAS was conducted on 6 strains (Xa3353, Xa484, ZM4, Chito, UNZA and LSK). QTLs on pv3, pv7, pv9 & pv 11 were identified as very important in conditioning resistance against the Zambian strains.
![20230530_153052 - Copy_edited.jpg](https://static.wixstatic.com/media/b134c0_e31ad45d02534d8e80f186766c659134~mv2.jpg/v1/crop/x_72,y_0,w_2773,h_2245/fill/w_574,h_465,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/20230530_153052%20-%20Copy_edited.jpg)
Mr Mwiinga Mulube
![Mwiinga 01_edited.jpg](https://static.wixstatic.com/media/b134c0_a6f536a241c948a38fccf549584a8e5c~mv2.jpg/v1/crop/x_0,y_13,w_653,h_555/fill/w_199,h_169,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/Mwiinga%2001_edited.jpg)
i
![Cbb Zambia 01_edited.jpg](https://static.wixstatic.com/media/b134c0_33f6eabc6c7b468ba676d2805d1823d7~mv2.jpg/v1/crop/x_35,y_0,w_475,h_418/fill/w_192,h_169,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/Cbb%20Zambia%2001_edited.jpg)
ii
![CBB Mwiiga 02_edited.jpg](https://static.wixstatic.com/media/b134c0_2e03e6969f384736964d3ce86cca4252~mv2.jpg/v1/crop/x_67,y_0,w_510,h_433/fill/w_199,h_169,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/CBB%20Mwiiga%2002_edited.jpg)
iii
![20230515_114148 - Copy.jpg](https://static.wixstatic.com/media/b134c0_c0fe5240be704d25a89ee0ffb7dfc769~mv2.jpg/v1/crop/x_486,y_0,w_3653,h_3468/fill/w_178,h_169,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/20230515_114148%20-%20Copy.jpg)
iv
![20230712_170202.jpg](https://static.wixstatic.com/media/b134c0_f119665ad1884728b0b6a1e654c44dbb~mv2.jpg/v1/crop/x_0,y_0,w_3166,h_2862/fill/w_187,h_169,al_c,q_80,usm_0.66_1.00_0.01,enc_avif,quality_auto/20230712_170202.jpg)
v
Mr Mulube collecting diseased samples during a CBB diagnostic survey (i); CBB symptoms on leaves (ii); and in a severely affected field (iii); at the University of California, Davis, during a five-month training visit in 2023 (iv); with Travis Parker (v).