Intersubgeneric hybridization between Glycine max and G. tomentella: Production of F1, amphidiploid, BC1, BC2 BC3 and fertile soybean plants

Authors: Singh, Ram; Nelson, Randall

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2015
Publication Date: 4/3/2015
Publication URL: http://handle.nal.usda.gov/10113/61839
Citation: Singh, R.J., Nelson, R.L. 2015. Intersubgeneric hybridization between Glycine max and G. tomentella: Production of F1, amphidiploid, BC1, BC2 BC3 and fertile soybean plants. Theoretical and Applied Genetics. 128:1117-1136. doi: 10.1007/s00122-015-2494-0.

Interpretive Summary: Wild relatives of crop plants are an important source of genetic diversity and this is especially true for soybean. Soybean is one of the least diverse crop species and only one wild relative can be easily crossed with soybean. There are 26 perennial species that are very distant relatives of soybean that have not been used in soybean breeding. The objective of this research was to determine which perennials could be used in crosses with soybean to produce fertile progeny. We hybridized eight soybean varieties with six lines of G. tomentella with 78 chromosomes and one line of G. tomentella with 40 chromosomes. We also crossed with one line each of G. argyrea and G. latifolia. Successful results were obtained with the soybean cultivar Dwight and a 78 chromosome G. tomentella accession PI 441001. Developing seeds from 19 to 21 day old pods were cultured in the laboratory. Media were developed to induce multiple embryos per seed. Hybrid plants, which were sterile, were transplanted to pots in greenhouse and the chromosome number was doubled using colchicine. It required three additional series of crossing back to Dwight to produce fertile plants with 40 chromosomes, which soybean plants have. The effort required to produce fertile progeny from crosses with perennial Glycine species varies among species and among lines with species. This research reports procedures that were success with one line of G. tomentella but modifications of this procedure may be successful with perennial Glycine species and lines. These results are of use to soybean breeders and geneticists who are interested in genetic diversity.

Technical Abstract: The genetic resources of the 26 species of the subgenus Glycine have not been exploited to broaden the genetic base of soybean (Glycine max; 2n = 40). Initially, we hybridized eight soybean cultivars with six accessions of 78- and one accession of 40-chromosome G. tomentella. One accession of G. argyrea and G. latifolia was also included. The objectives of this study were to develop methods for producing F1, amphidiploid, BC1, BC2, BC3 and fertile soybean plants by hybridizing soybean cv. ‘Dwight’ and 78- chromosome G. tomentella accession PI 441001. Developing seeds from 19 to 21day old pods were cultured aseptically in various media formulations. Seed maturation and multiple embryo generation media were developed. F1 plants with shoots and roots (2n = 59) were transplanted to pots in greenhouse. Amphidiploid (2n = 118) plants were induced by colchicine, and then backcrossed to’ Dwight’. We obtained BC1 (2n = 79) plants through in vitro and 43 mature BC2F1 seeds were harvested. Chromosome numbers in 32 seedlings ranged from 2n = 55-99. Vegetative lethality was common among BC2F1 plants, and 15 surviving plants were morphologically distinct, sterile, and had chromosome numbers ranging from 2n = 56-59. All produced mature pods and seeds after being backcrossed a third time to ‘Dwight’. Chromosome numbers of the BC3F1 plants ranged from 2n = 40-49. Derived fertile soybeans were first planted in the field in 2008. This study sets an example for hybridizing domesticated soybean (primary gene pool) with species of the subgenus Glycine (tertiary gene pool).