THE JOURNAL OF AGRICULTURE OF THE UNWERS1TY OF PUERTO RICO Issued by the Agricultural Experiment Station of the University of Puerto Rico, Mayagilez Campus, for the publication of articles and research notes by staff members or others, dealing with scientific agriculture in Puerto Rico and elsewhere in the Caribbean Basin and Latin America. VOL.93 JANUARY AND APRIL 2009 No. 1.2 Ploidy level and genomic composition of Musa spp. accessions at the USDA-ARS Tropical Agriculture Research Station1'2 Brian M. IrishS*, Arnelis Crespo 3, Ricardo Goenaga3, Randall Niedz 4 and Tomas Ayala-Silua6 J. Agric. Univ. P.R. 93(1.2):1-21(2009) ABSTRACT Plant germpiasm collections serve as repositories for important genes. However, insufficient and inaccurate characterization of the genetic diversity in a collection can slow or can prevent full utilization of genetic resources. Bananas and plantains (Musa spp., Colia) are some of the most important food crops in the world. Germpiasm characterization efforts In Musa have fo- cused mostly on agronomic and morphological traits although with the ad- vent of molecular markers genotypic characterization efforts are increasing. Genomlc composition in Musa is based on a plant's ploidy level and on whether it is of a hybrid origin. Genomic compositions of Musa spp. have been associated with disease and insect resistance, production and flavor characteristics. The Musa spp. collection of the USDA-ARSTropical Agricul- ture Research Station consists of 135 accessions, many of which are of un- known genomic composition. in an effort to better characterize the collec- tion, RAPO and PCR-RFLP markers, as well as flow cytometry, were employed to determine genomic composition and ploidy level. Plant acces- 'Manuscript submitted to Editorial Board 7 August 2008. The authors would like to thank Dr. George Ude and Mr. Scott Hyndman for their critical review of early versions of the manuscript. 'USDA-ABS, Tropical Agriculture Research Station, MayagOez, 2200 Pedro Albizu Campos Ave., Suite 210, Mayaguez, PR 00680. *To whom reprint requests should be ad- dressed. Email address: Brian.Jrish@ars.usda.gov USDA-ARS U. S. Horticultural Research Laboratory, 2001 South Rock Road Ft. Pierce, FL 34945. USDA-ARS Subtropical Horticulture Research Station, 13601 Old Cutler Rd., Mi- ami, FL.