ICRISAT Archival Report 2006 - The seedlings of success in the ...

Activity C2.2: Understand the in situ dynamics of crop-to-wild and crop-to-weed genetic introgression in
Kenya at the country scale
Milestones 2.2.1: Paper accepted on Sorghum crop-to-wild introgression rates in contrasted Kenyan agroecological
regions (FS, SdV, DK, KARI, University of Free State, University of Hohenheim) 2008
During 2006 an extensive germplasm collection of cultivated landraces, cultivated-wild hybrids and wild sorghums
was conducted in the Turkana, Western, Coastal and parts of Eastern provinces of Kenya. A total of 218 samples
were collected. DNA, suitable for genotyping, has been isolated from all of these samples. 30 SSR markers were
identified for diversity assessment and to date all samples have been genotyped with 12 of these markers. Additional
collection trips are planned for 2007 to collect sorghum that mature in different seasons and to fill gaps that were not
covered in the first collection. All additional samples will be added to the current 218 for genotyping to estimate the
crop-wild geneflow.
F Sagnard, S de Villiers and DKiambi
Activity C2.3: Determine gene flow and outcrossing rates between cultivated, wild and weedy sorghum types and
assess hybrid fitness in diverse ecologies using conventional and molecular markers
Milestone C.2.3.1: Molecular analytical laboratory equipped and 10 molecular markers identified for gene flow
studies by 2007
The BioScience for Eastern and Central Africa (BECA) facilities were identified for the bulk of our studies. Other
activities will be conducted in the Biotechnology laboratory, ICRISAT-India. There are over 100 SSR markers for
sorghum that are publicly available and many more are being developed every month. SSR markers will be picked
from the sorghum linkage map. SSR markers that are present/frequent in leading sorghum varieties in ESA but
absent/rare in wild sorghums will be identified. Work on genotyping of leading sorghum varieties in ESA (22
varieties sent to CSIR) and wild sorghums was started at BECA, Nairobi in November 2006. Seeds from all the
genotypes were germinated in trays and DNA extracted from10-day old seedlings using the CTAB method (Doyle
and Doyle, 1987). A total of 24 sorghum SSR markers showing high polymorphism under the Generation Challenge
Program Project are being evaluated. SSR markers that will show polymorphism between cultivated and wild/weedy
sorghum will be identified. Other SSR markers will be tested later.
S Mwangi and MA Mgonja
Milestone C.2.3.2: Agro-ecosystem characterization and genetic sampling on the Intensive Study Site (South Meru
District) completed and reported by 2007
During 2006, a Ph.D student was recruited in this project. He conducted a preliminary assessment of the chosen 8 x
8 km intensive study site to develop an appropriate sampling methodology for the further collections of cultivated
and wild sorghum planned in this project. The aim was to identify the optimum number of farms that have to be
sampled in order to acquire all the sorghum varieties grown in a particular target region and also to obtain some
preliminary information on crop diversity and wild sorghum ecological distribution and identification criteria. This
was done along an altitudinal gradient of 750 to 1200 masl and across 4 different language groups and it was
concluded that at least 27 farms/sites at an interval of 20 m altitudinal difference need to be sampled in order to
include all the varieties grown in the survey area. The presence of wild/weedy sorghums in close proximity to the
cultivated counterpart seems to point to the occurrence of crop-wild geneflow. The planned studies on mating
systems and geneflow will confirm both the historical and present occurrences. A more detailed survey is planned
for 2007.
F Sagnard, S de Villiers and D Kiambi
Milestone C.2.3.3: Out crossing and gene flow between at least 5 cultivated and wild or weedy sorghum determined
and reported by 2009
In situ introgression in natural habitat:
Seed samples of cultivated and weedy sorghums were collected from three districts (Busia, Teso, and Siaya) located
in Western and Nyanza Provinces of Kenya in July 2006. The samples were planted at Kiboko, Kenya in November
2006 for morphological characterization. The samples will further be evaluated in the laboratory in 2007 using 10
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