Can Heterosis Be Predicted by Genetic Similarity Measures in Soybean?

摘要

Choosing parents is one of the most challenging aspects of plant breeding. There can be several criteria in the selection of parents when breeding for high yield. Two of the most common criteria are high yield per se, and genetic distance between parents. Yield is relatively easy to measure with field evaluations, but the genetic relationship is not because of complicated pedigrees. Two measures of genetic distance have been proposed. One is the coefficient of parentage (CP) or coancestry, based on pedigree analysis and defined as the probability that a random gene from one individual is identical by descent to a random gene of another. The other is the RFLP-based genetic similarity estimate (RFLP-GS), which is defined as the proportion of RFLP bands identical between two genotypes, compared to the total number of bands. It is important to determine whether these two measures of genetic distance are only theoretical concepts or have real meaning for the breeder in the selection of parents. One wayto validate the utility of genetic similarity measures is in the prediction of the genetic variance among the progeny (inbred lines) in a biparental cross situation. There is some evidence that crossing parents with low CP (less genetic relationship), increases the genetic variance among inbred lines in soybean (Manjarrez-Sandoval, 1996).