Screening sweetpotato for drought tolerance in the Philippine highlands and genetic diversity among selected genotypes

Local germplasm of high-yielding traditional cultivars and open-pollinated (OP) progenies of sweetpotato [Ipomoea batatas (L.)] were screened for drou ght tolerance in swidden and postrice conditions in the Philippine highland s. Several clones from OP progenies and traditional cultivars showed some d rought tolerance based on the yields of marketable storage roots. Under swi dden conditions, the local cultivar Tokano, had the highest yield, Likewise , the traditional cultivar Kalbo-oy, produced the best yields in post-rice paddies. To obtain genetic markers that will be used in future breeding, ge netic diversity analysis was performed. Genomic deoxyribonucleic acid (DNA) from seven sweetpotato genotypes, selected from those which produced stora ge roots under drought conditions, was subjected to Random Amplified Polymo rphic DNA (RAPD) analysis. Twenty decamer primers were tested and 16 yielde d DNA-amplification products. Among the 97 scored bands, 77 were polymorphi c (79.38%), Genotype-specific DNA markers were also identified. The pairwis e marker difference between genotypes ranged from 0.378 to 0.936, indicatin g a broad range of genetic diversity. A phenogram of the genetic relationsh ips among those genotypes is presented.