ASSESSMENT OF INTER-INBRED AND INTRA-INBRED LINE VARIABILITY IN SUNFLOWER (HELIANTHUS-ANNUUS) BY RFLPS

The restriction fragment length polymorphism (RFLP) between 26 sunflow er inbred lines was evaluated with 81 probe-enzyme combinations involv ing 51 cDNA clones and 4 restriction enzymes (HindIII, EcoRI, EcoRV, a nd BglII). An average of 4.6 fragments and 4.9 profiles was detected p er probe-enzyme combination, across all inbred lines. The RFLPs reveal ed were characterized by a high percentage (>70%) of multifragment pro files. Nei's average gene diversity was calculated to measure the gene tic variability within cultivated sunflower; the average gene diversit y computed with 81 probe-enzyme combinations was 0.59. The relationshi ps between the 26 sunflower inbred lines were analysed by estimates of Nei's F index, which ranged from 0.50 to 0.91, as well as Nei's genet ic distance, d, which varied from 0.05 to 0.41. A UPGMA (unweighted pa ir-group arithmetic average clustering) dendrogram was constructed usi ng the genetic distance matrix; likewise, a principal component analys is was performed using the F matrix. The results obtained from the two clustering analyses allowed the separation of maintainer lines (femal es) from restorer lines (males). After partitioning the 26 lines into a pool of maintainer lines and a pool of restorer lines, the estimatio n of gene differentiations showed that the absolute difference (D-m) b etween females and males was only about 5%. Intraline variability was also examined in 4 sunflower inbred lines, using 30 probe-enzyme combi nations. Heterogeneity at varying levels was detected in 3 of the 4 li nes studied. The RFLPs detected by this set of selected clones in the 26 inbred lines suggests that RFLPs could be very useful descriptors f or sunflower inbred line and variety studies.