An Evaluation of Segregation Distortion in Wide Crosses of Safflower

Abstract

Segregation distortion (SD) which is defined as a significant deviat ion of the observed genotypic frequencies of a locus from the expected Mendelian ratios is a common phenomenon in most mapping studies. This study was conducted to evaluate the occurrence, of the nature and level of the segregation distortion in three wide crosses of Carthamus tinctorius L. and C. oxyacanthus Bieb. using ISSR fingerprinting. Like other interspecific crosses, and since these two species have characters which could be capable of distorting segregation, we expected the segregation distortion could possibly occur. Our results showed that only one population (C4110 × Isf2) deviated fro m the expected ratio of 1:1 and the other two populations (Isf2 × C4110 and C111 × Isf2) exh ibited no distortion. Moreover, the heterogeneity chi square test over the populations indicated that the populations were homogeneous and showed no distortion. It seems that the observed distortion in population C4110 × Isf2 may be due to both genotyping errors and self-incompatib ility and, other expected distorting factors could not induce any deviations. This proportion of d istortion is the lowest range of distortion in interspecific crosses seen yet. Surprisingly, cyto-nuclear interactions could significantly increase the inherited maternal-specific markers. In addit ion, our results confirm that the two species of C. tinctorius and C. oxyacanthus have strongly close relationships and interspecific hybridizat ion between two species could directly be exploited in broadening the genetic base of safflower and improving the crop for biotic and environmental ab iotic stresses. Also, our result suggests that ISSR molecu lar markers can be an effective and promising marker system allowing for the establishment of a linkage map along with other molecular markers.