A Comparison of Rhizobial Strain Compatibilities of Glycine max and its Progenitor Species Glycine soja1
- T. E. Devine2
Glycine soja Seib. and Zucc. is considered the wild progenitor species from which the domesticated soybean [G. max (L.) Merr.] was developed. Glycine soja hybridizes readily with G. max and is a source of agronomically valuable genes for introgressing into G. max. Such introgression could result in concomitant introgression of genes controlling rhizobial symbiosis. Because little is known of the nodulation response of G. soja with U.S. rhizobial strains, we tested Asiatic G. soja plant introductions for nodulation response with bradyrhizobial strains USDA 7 and USDA 61 isolated from the USA. For comparison, Asian plant introductions of G. max were also tested. Seed of 537 lines of G. soja and 691 lines of G. max originating from China, Japan, Korea, and USSR in Maturity Groups OO thru ✕ were evaluated for nodulation response. Five seeds of each line were decontaminated in 50% ethyl alcohol, planted in vermiculite in growth trays, inoculated with 4- to 7-day-old broth cultures of rhizobia, and grown in the greenhouse for 4 to 5 weeks. then, roots were extracted and nodulation response was determined by visual examination. Both G. soja and G. max were polymorphic for effective vs. ineffective nodulation with both strains of bradyrhizobia. This suggests that polymorphism existed in G. soja prior to domestication of G. max and that G. max was domesticated from a polymorphic population of G. soja. The frequency of ineffective nodulation in G. soja with both strain USDA 7 (10.9%) and USDA 61 (63.4%) was higher than in G. max (2.4%, 26.4%, respectively). Therefore, use of G. soja in breeding programs could increase the probability of ineffective nodulation with these bacteria in derived lines. The marked difference in the nodulation incompatibilities between G. soja and G. max from Korea suggest that the G. max introductions were not domesticated from the G. soja lines from Korea and that there has not been a substantial introgression of genes controlling nodulation from Korean G. soja into Korean G. max.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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