Bread wheat: F1 hybrid performance and parental diversity estimates using molecular markers |
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| Authors: | M Perenzin M Corbellini M Accerbi P Vaccino B Borghi |
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| Institution: | (1) Istituto Sperimentale per la Cerealicoltura, Via Mulino No. 3 20079 S. Angelo Lodigiano, Italy |
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| Abstract: | In wheat, the possibility of introducing F1 seed into practical agriculture has been greatly enhanced by the discovery of effective chemical hybridising agents (CHAs).
Although some technical and economic problems concerning the use of CHAs for large-scale production of F1 seed remain to be solved, a first group of F1 hybrids has been submitted for registration in several European countries i.e., France, England and Italy. Combining ability
for grain yield and several agronomic and quality traits was studied in an eight-parent diallel cross. Highly significant
combining ability effects were observed for all the traits while specific combining ability effects were statistically significant
for grain yield, plant height, heading time and Chopin alveograph parameter P. The level of genetic diversity between parents
as estimated using molecular markers is considered a tool for predicting the hybrid performance and heterosis of crosses.
To explore this possibility, RFLP and RAPD markers were used to predict the performance of hybrids obtained from diallel and
top crosses. The performance of the hybrids was determined in replicated plot trials sown at normal seed density in several
locations. Coefficient of parentage (rp), based on pedigree information for all the pairwise combinations of the parents ranged
from 0.01 to 0.34. The parents were assayed for random amplified polymorphic DNA (RAPD) with 87 primers which generated 304
polymorphic bands. Genetic similarity between parents, estimated on the basis of common bands using the Jaccard's similarity
coefficient (J), ranged from 0.25 to 0.57. Correlation between parental diversity and hybrid performance was generally weak.
A positive trend is observed in the yield potential of the hybrids produced in Italy in the last 10 years. In fact among the
first set of hybrids produced by random crossing of the available cultivars, none produced 10% more than the checks whereas
the last generation of hybrids includes combinations yielding 15% more than the best standards. Our results clearly indicate
the need to develop specific strategies in order to identify and/or to select parental lines with a high level of general
combining ability (GCA) and specific combining ability (SCA). The information regarding the genetic diversity of the parental
lines do not appear helpful for predicting F1 performance.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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| Keywords: | Triticum aestivum combining ability heterosis genetic distance |
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