Development of a Genetic Linkage Map for Genes Associated with Resistance and Susceptibility to Fusarium oxysporum f. sp. cubense from an F 1 Hybrid Population of Musa acuminata ssp. malaccensis F. Kayat 1 , N. Bonar 2 , R. Waugh 2 , S. Rajinder 3 , A.R. Rahimah 3 , K.A. Rashid 1 and R.Y. Othman 1 1 Institute of Biological Sciences, Faculty of Sciences, Faculty of Sciences, University of Malaya, 50603 Kuala Lumpur Malaysia 2 Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, UK 3 Malaysia Palm Oil board (MPOB), 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia Keywords: banana, resistance breeding, Fusarium wilt, ‘tropical race 4’, screening Abstract Conventional banana breeding for resistance to Fusarium wilt is hampered by sterility, triploidy, long generation time and the lack of appropriate testing sites. Biotechnological advances involving embryo rescue culture, rapid micropropagation, somatic embryogenesis and molecular marker-assisted selection (MAS) breeding provide opportunities to develop cultivars adapted to changing environments. Wild, seeded Musa acuminata ssp. malaccensis has been found to be resistant to Fusarium oxysporum f. sp. cubense (Foc) ‘tropical race 4’ and hence could be useful in the study of populations for the development of molecular markers and gene cloning. 607 AFLP markers have been generated from 14 EcoRI/Mse1 primer combinations and 39 PstI/MseI primer combinations in an F 1 hybrid population of a controlled cross between a selected resistant male and a susceptible female. 166 markers were found to be present in the resistant parent, but absent in the susceptible female. 215 markers have been found to be present in the susceptible female, but absent in the resistant parent. Another 226 markers were present in both parents. All these markers segregated in F 1 hybrids are potentially very useful for MAS. Two linkage maps for putative resistance and susceptibly markers to Foc have been developed from data obtained. INTRODUCTION Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is a serious soil-borne disease and has caused considerable losses to the banana export trade (Rutherford, 1999). Four physiological races of Foc have been reported based on their selective pathogenicity in different banana cultivars. Race 1 is virulent on ‘Gros Michel’ (AAA genome), race 2 on ‘Bluggoe’ (ABB genome), race 3 on Heliconia and race 4 attacks the Cavendish cultivars (AAA genome) as well as ‘Gros Michel’ and ‘Bluggoe’. Numerous disease control strategies exist, such as soil amendment with calcium or organic matter and fumigation with methyl bromide. However, these only provide temporary solutions to the problem. Planting resistant banana cultivars is considered the best approach, as it is economical, effective and practical in the long term. Attempts to develop genotypes with resistance to Fusarium wilt using conventional breeding have had limited success due to low reproductive fertility, polyploidy or complete sterility. The wild Musa acuminata ssp. malaccensis is highly resistant to Fusarium oxysporum f. sp. cubense race 4 (Javed et al., 2004). Seed progenies derived from in vitro embryo culture have been found to be segregating for resistance and susceptibility to Foc race 4. Therefore, they could be a great resource of resistance for breeding strategies, as they are also fertile and produce a large number of seeds. Developments in molecular markers have provided tools for genetic relationship studies among breeding lines (Staub and Serquen, 1996; Saghai et al., 1997). Quantitative Trait Loci (QTL) analysis has been made possible by numerous improved methods of molecular marker analysis. Identification of important QTL regions could enhance plant 333 Proc. IS on Banana Crop Prot., Sust. Prod. & Impr. Livelihoods Eds.: D. Jones and I. Van den Bergh Acta Hort. 828, ISHS 2009