Selection and molecular characterization of faba bean lines resistant to broomrape (Orobanche crenata Forsk)

摘要

Three lines of faba bean derived from three bi-parental crosses (Giza 402 X Giza 674, Giza 402 X Giza blanca and Giza 674 X Giza blanca) were selected according to their high performance in seed yield under heavy natural infestation with Orobanche.The selected lines and their parents were evaluated for Orobanche resistance and seed yield under both heavy natural infestations with Orobanche and normal field (lower natural infestation). The selected lines showed significantly lower levels of Orobanche infestation than their resistant parents Giza 674 and Giza 402 while, Giza blanca revealed the highest level of infestation. The selected lines significantly exceeded their best-parents in Orobanche resistance and seed yield. However, the genetic advance for Orobanche-tolerance was relatively higher than that for seed yield. In this respect, under heavy infestation the genetic advance ranged from 9.09 to 12.12 percent in number of Orobanche spikes/m~2 and from 6.87 to 11.41 percent in dry weight/m~2while, it ranged from 7.77 to 9.07 percent in seed yield. The results indicated that selection for higher yield under heavy infestation with Orobanche is probably the most feasible approach for developing Orobanche-resistant faba bean genotypes. In the RAPD-PCR analysis, five primers reacted with the selected lines and then- parents producing a total of 41 DNA bands, 26 (63.41 percent) of them were conserved among all tested genotypes while 15 fragments were polymorphic (36.59 percent). The pairwise differences detected by RAPD-PCR analysis were used to calculate the genetic distance and to construct a dendrogram tree among the selected lines and their parents. High similarity (92.5 percent) and very low genetic distance (0.078) were found between thetwo varieties Giza-402 and Giza-674. The cultivar Giza blanca possessed less similarity when compared with Giza-674 (69.23 percent) and Giza-402 (71.05 percent). The two DNA fragments 1530 (OPO-15) and 978 bp (A2) were specific markers for Giza-674 while, 1129 bp (A1) was specific marker for Giza-402. In addition, two DNA fragments at 2428 and 1325bp (A2) were found to be positive markers for Orobanche-resistance in faba bean. Most of the DNA fragments amplified from the selected lines were inherited from the original resistant parents Giza 674 and Giza 402 and reflecting the superiority of the selected lines in Orobanche-resistance. These results indicated that bulk-selection within the cross between the high resistant varieties concentrated the favorable alleles of Orobanche resistance in the selected lines.