Belayneh Admassu

Development of Microsatellite Markers and Analysis of Genetic Diversity and Population Structure of Colletotrichum gloeosporioides from Ethiopia.

Twenty three polymorphic microsatellite markers were developed for citrus plant pathogenic fungus, Colletotrichum gloeosporioides, and were used to analyze genetic diversity and population structure of 163 isolates from four different geographical regions of Ethiopia. These loci produced a total of 118 alleles with an average of 5.13 alleles per microsatellite marker. The polymorphic information content values ranged from 0.104 to 0.597 with an average of 0.371. The average observed heterozygosity across all loci varied from 0.046 to 0.058. The gene diversity among the loci ranged from 0.106 to 0.664. Unweighted Neighbor-joining and population structure analysis grouped these 163 isolates into three major groups. The clusters were not according to the geographic origin of the isolates. Analysis of molecular variance showed 85% of the total variation within populations and only 5% among populations. There was low genetic differentiation in the total populations (FST = 0.049) as evidenced by high level of gene flow estimate (Nm = 4.8 per generation) among populations. The results show that Ethiopian C. gloeosporioides populations are generally characterized by a low level of genetic diversity. The newly developed microsatellite markers were useful in analyzing the genetic diversity and population structure of the C. gloeosporioides populations. Information obtained from this study could be useful as a base to design strategies for better management of leaf and fruit spot disease of citrus in Ethiopia.

Conflicting mapping results for stem rust resistance gene Sr13.

Theor Appl Genet (2011) 122:659 DOI 10.1007/s00122-010-1495-2 COMMENT Conflicting mapping results for stem rust resistance gene Sr13 J. Dubcovsky • F. Ordon • D. Perovic B. Admassu • W. Friedt • Z. Abate • W. Zhang • S. Chao Published online: 14 December 2010 O The Author(s) 2010. This article is published with open access at Springerlink.com Two manuscripts with conflicting results on the mapping location of stem rust resistance gene Sr13 in wheat are published in this issue of TAG (Admassu et al. and Simons et al.). Both resistance genes were mapped on the long arm of chromosome 6AL, but the gene mapped by Admassu et al. between markers barc37 and wmc256 is more than 50 cM proximal to the one mapped by Simons et al. between markers CD926040 and BE471213. After the publication of the two manuscripts in TAG online, the authors of both manuscripts became aware of the conflicting results and they exchanged the critical hexaploid wheat cytogenetic stocks Khapstein/9*LMPG (developed by Dr. D. Knott) and the recurrent parent LMPG to deter- mine the source of the differences. In addition, they requested seeds for these two stocks from the U.S. Cereal Disease Laboratory in Saint Paul Minnesota (Dr. Yue Jin) and from Canada Agri-Food, Winnipeg (Dr. Tom Fetch). The online version of the original articles can be found under doi:10.1007/s00122-010-1433-3 and 10.1007/s00122-010-1444-0. J. Dubcovsky (&) Z. Abate W. Zhang Department of Plant Sciences, University of California, Davis, CA 95616, USA e-mail: jdubcovsky@ucdavis.edu F. Ordon D. Perovic B. Admassu Julius Kuehn-Institute, Federal Research Institute for Cultivated Plants (JKI), Institute for Resistance Research and Stress Tolerance, Erwin-Baur-Str. 27, 06484 Quedlinburg, Germany W. Friedt Institute of Crop Science and Plant Breeding I, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany S. Chao USDA-ARS, Biosciences Research Laboratory, 1605 Albrecht Blvd N, Fargo, ND 58102-2765, USA Analysis of these stocks with molecular markers for the long arm of chromosome 6AL revealed that the Khapstein/ 9*LMPG seed stock used in the Admassu et al. paper was different from the other three Khapstein/9*LMPG stocks. Molecular markers barc37, barc107, barc118, barc1165, gwm570, wmc179, wmc256, wmc580, and cfd2 all showed different bands in the seed stock used in the Admassu paper relative to the seed stocks from the University of Califor- nia, the Cereal Disease Laboratory and Agri-Food Canada. These results indicate that the Khapstein/9*LMPG seed stock used in the Admassu paper is different from the other three. Since the Khapstein/9*LMPG hexaploid genetic stock defines the gene name Sr13, the gene mapped by Admassu et al. is most likely not Sr13 and should be renamed. The Khapstein/9*LMPG developed by Dr. D. Knott is polymorphic with the LMPG recurrent parent only for markers closely linked to the stem rust resistance gene mapped in the four tetraploid populations in the distal region of chromosome arm 6AL (barc104b and dupw167) by Simons et al. This observation, together with the fact that Sr13 was originated in tetraploid wheat (Khapli), provides indirect evidence that the gene mapped by Simons et al. is Sr13. Mapping the stem rust resistance gene present in the correct Khapstein/9*LMPG stock in an hexaploid segregating population will provide the final answer. Interestingly, both genes confer resistance to the new stem rust race Ug99 (TTKSK) suggesting that it would be possible to combine the two sources of resistance to Ug99 in the same 6AL arm. We have initiated crosses between the correct Khapstein/9*LMPG genetic stock and the source of the Admassu et al. Ug99 resistance to recombine both genes. Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which per- mits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

A Look into Genetic Diversity of Enset (Ensete ventricosum (Welw.) Cheesman) Using Transferable Microsatellite Sequences of Banana in Ethiopia

Microsatellite sequences are one of the best options for the study of genetic diversity in plant species. However, because of the high cost of their development, it is important to test whether existing sequences from related species can be exploited. Enset (Ensete ventricosum (Welw.) Cheesman) has remained largely unimproved partly due to lack of its genetic information, thus there is a need to study the genetic diversity of current accessions and build on it to develop new cultivars/varieties with desired agronomic traits. Transferability of 71 SSR loci from banana (Musa accuminata) to enset was investigated using 220 Enset accessions. Among the 71 SSRs tested, 12 (16.9%) were successfully transferable to enset. Eleven (16.9%) of these were used to examine the diversity of the 220 enset accessions that had been collected from eight different zones in Ethiopia.