Characterization of disomic alien addition lines from an intersubgeneric cross between Glycine max and G. tomentella and phenotypic variation within those lines and their progenies

Abstract

Disomic alien addition lines (DAALs, 2n = 42) were obtained from an intersubgeneric cross between Glycine max [L.] Merr. cv . Dwight (2n = 40, G1G1) and Glycine tomentella Hayata (PI 441001, 2n = 78, D3D3CC). These DAALs had two homologous G. tomentella chromosomes. In some progenies of the DAALs the extra G. tomentella chromosomes were eliminated. One objective of this research was to identify differences in gene expression between a DAAL (LG13-7552) and one of its 2n = 40 progenies (LG12-7063). RNA-sequencing documented that many genes critical to fundamental plant growth and related to stress and defense responses were differentially expressed. DNA and RNA-sequencing data showed that the gray pubescence of LG12-7063 was due to a novel adenine deletion in the T locus. When the DAALs were grown in the field, progeny were identified that possessed characteristics that were absent in both parents. Additional objectives of this research were to document this phenotypic variation and to determine the cause of these changes. All off-type progenies lost their G. tomentella chromosomes and reverted to the normal soybean chromosomal state (2n = 40). Significant variation was observed among the 2n = 40 progenies for the several qualitative and quantitative traits. Field research documented an average reversion frequency within the DAAL rows of 4%. Genotypic data showed that the revertants (2n = 40) differed from the sister DAAL lines by mostly heterozygous polymorphisms throughout the genome.Natural cross-pollination was the most probable cause of observed variation but the reasons for the elevated level of cross pollination and the mechanisms for long distance pollen transfer remain unknown.

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