Abstract
Abstract Seed dormancy allows weedy rice ( Oryza sp.) to persist in rice production systems. Weedy and wild relatives of rice ( Oryza sativa L.) exhibit different levels of dormancy, which allows them to escape weed management tactics, increasing the potential for flowering synchronization, and therefore gene flow, between weedy Oryza sp. and cultivated rice. In this study, we determined the genetic diversity and divergence of representative dormant and nondormant weedy Oryza sp. groups from Arkansas. Twenty-five simple sequence repeat markers closely associated with seed dormancy were used. Four populations were included: dormant blackhull, dormant strawhull, nondormant blackhull, and nondormant strawhull. The overall gene diversity was 0.355, indicating considerable genetic variation among populations in these dormancy-related loci. Gene diversity among blackhull populations (0.398) was higher than among strawhull populations (0.245). Higher genetic diversity was also observed within and among dormant populations than in nondormant populations. Cluster analysis of 16 accessions, based on Nei’s genetic distance, showed four clusters. Clusters I, III, and IV consisted of only blackhull accessions, whereas Cluster II comprised only strawhull accessions. These four clusters did not separate cleanly into dormant and nondormant populations, indicating that not all markers were tightly linked to dormancy. The strawhull groups were most distant from blackhull weedy Oryza sp. groups. These data indicate complex genetic control of the dormancy trait, as dormant individuals exhibited higher genetic diversity than nondormant individuals. Seed-dormancy trait contributes to population structure of weedy Oryza sp., but this influence is less than that of hull color. Markers unique to the dormant populations are good candidates for follow-up studies on the control of seed dormancy in weedy Oryza sp.
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Claims 10
Claim · model-written summary
Overall diversity at dormancy-related loci was 0.355.
Verbatim
e0“The overall gene diversity was 0.355, indicating considerable genetic variation among populations in these dormancy-related loci”
t0“Weedy Rice”
Claim · model-written summary
Blackhull populations had greater gene diversity than strawhull populations.
Verbatim
e0“Gene diversity among blackhull populations (0.398) was higher than among strawhull populations (0.245)”
t0“Weedy Rice”
Claim · model-written summary
Dormant populations had higher diversity within and among populations than nondormant populations.
Verbatim
e0“Higher genetic diversity was also observed within and among dormant populations than in nondormant populations”
t0“Weedy Rice”
Claim · model-written summary
Cluster analysis yielded four clusters.
Verbatim
e0“Cluster analysis of 16 accessions, based on Nei’s genetic distance, showed four clusters”
t0“Weedy Rice”
Claim · model-written summary
Three clusters comprised blackhull accessions.
Verbatim
e0“Clusters I, III, and IV consisted of only blackhull accessions”
t0“Weedy Rice”
Claim · model-written summary
Cluster II comprised only strawhull accessions.
Verbatim
e0“Cluster II comprised only strawhull accessions”
t0“Weedy Rice”
Claim · model-written summary
Clusters did not separate cleanly by dormancy.
Verbatim
e0“These four clusters did not separate cleanly into dormant and nondormant populations”
t0“Weedy Rice”
Claim · model-written summary
Strawhull groups were most distant from blackhull groups.
Verbatim
e0“The strawhull groups were most distant from blackhull weedy Oryza sp. groups”
t0“Weedy Rice”
Claim · model-written summary
Dormancy contributed less to population structure than hull color.
Verbatim
e0“Seed-dormancy trait contributes to population structure of weedy Oryza sp., but this influence is less than that of hull color”
t0“Weedy Rice”
Claim · model-written summary
Markers unique to dormant populations were proposed for follow-up study.
Verbatim
e0“Markers unique to the dormant populations are good candidates for follow-up studies on the control of seed dormancy in weedy Oryza sp.”