Genetic diversity of ash gourd [Benincasa hispida (Thunb.) Cogn.] inbred lines based on RAPD and ISSR markers and their hybrid performance

Ten inbred lines of ash gourd [Benincasa hispida (Thunb.) Cogn.] were crossed to produce 45 F1 hybrids (without reciprocal) which were evaluated along with the parents for 20 growth- and yield-related traits, in a replicated field trial. High level of heterosis was observed among the hybrids for most of the traits examined, including yield. These inbred lines were analysed by using 42 RAPD primers those produced 282 DNA marker bands. A total of 130 RAPD markers were obtained with a mean of 3.1 per primer, which in combination discriminated all the inbreds from each other. Pair-wise genetic distance measurements ranged from 0.07 to 0.31, suggesting a wide genetic diversity for these inbreds. These inberds were also analysed with five ISSR primers of which four were informative. Twenty-six ISSR marker bands were generated of which 11 were polymorphic with an average of 2.80 per primers. The percentage of polymorphic bands produced were higher in ISSR markers (>80%) than generated through RAPD markers (46%). Although the results indicated significant positive correlations of genetic distance with hybrid performance and heterosis, the RAPD based genetic distance measures and use of limited ISSR markers in this present study could not effectively predict hybrid performance in this crop. The genetic variation among ash gourd inbred lines examined, herein, defined a marker array (combined ISSR and RAPD) for the development of a standard reference for further genetic analyses, and the selection of potential parents for predicting hybrid performance and heterosis.