Comparisons of genetic and morphological distance with heterosis between Medicago sativa subsp. sativa and subsp. falcata |
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| Authors: | Heathcliffe Riday E Charles Brummer T Austin Campbell Diane Luth Patricia M Cazcarro |
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| Institution: | (1) Department of Agronomy, Iowa State University, Ames, IA, 50011, U.S.A;(2) Soybean and Alfalfa Research Laboratory, USDA-ARS, Beltsville Agricultural Research Center, Beltsville, Maryland, 20705, U.S.A |
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| Abstract: | Biomass yield heterosis has been shown to exist between Medicago sativasubsp. sativa and Medica gosativa subsp. falcata. The objective of this study was to gain a better understanding of what morphological and genetic factors were most highly
correlated with total biomass yield heterosis. We calculated genetic distances among nine sativa and five falcate genotypes
based on amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) DNA markers. Genetic distance did
not correlate with specific combining ability (SCA) or mid-parent heterosis. In contrast, a morphological distance matrix
based on seventeen agronomic and forage quality traits was significantly correlated with heterosis; the agronomic traits of
maturity, midseason regrowth, and autumn regrowth showed strong association with heterosis. Heterosis was also correlated
with subspecies. We suggest that in many cases progeny heterosis can be accounted for by the interaction of genes controlling
morphologically divergent traits between the parents. In other cases, progeny heterosis could also be due to divergence between
the parents at particular genetic loci that do not control field-level phenotypic differences. Genetic distanceper se between parental genotypes, based on neutral molecular markers, however, does not reflect the potential of individual genotypes
to produce heterosis in their progeny.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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| Keywords: | alfalfa falcata genetic distance heterosis morphological distance |
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