SOURCES OF POTENTIAL ERRORS IN THE APPLICATION OF RANDOM AMPLIFIED POLYMORPHIC DNAS IN CUCUMBER

The influence of tissue age, pathogen infestation, intrapopulation con tamination, and polymerase chain reaction (PCR) conditions were assess ed as sources of error in random amplified polymorphic DNA (RAPD) anal ysis. DNA from young, uninfected tissue provided the most consistent r esults. Plants infected with Sphaerotheca fuliginea Schl. (ex Fr.) Pol l. showed variation in RAPD banding patterns compared to those of unin fected plants. Differences in banding patterns were detectable when DN A from two inbred lines were mixed at dilution ratios of less than or equal to 20:1 but not greater than or equal to 50:1. Differing lots of commercially available 10x reaction buffer, MgCl2 stock solutions, an d Tag DNA polymerase affected RAPD banding patterns and overall yield. For reproducibility of RAPD assays, it may be necessary to optimize r eactions for specific lots of PCR reagents from either commercial or i n-house sources.