Natural occurrence of autopolyploidy within the allotetraploid-cultivated peanut

The cultivated peanut is classified as an allotetraploid species. During the past several years, abnormal plants with coarse stems, thick leaves and an occasional single seed per pod have been found within different cultivars and advanced breeding lines. The spontaneous natural occurrence of these plants has been very rare, and frequently they do not produce any pods or seed. However, over a 3‐year period (2001–2003), four individual plant selections with one mature seed per plant were found and saved. In 2003, another similar plant was also found that had the same plant characteristics, except for a single branch that had normal leaves with typical two‐seeded pods. A greenhouse study was conducted during the winter of 2003–2004. The four coarse stem individual plant selections from the previous years were planted along with the check cultivar ‘Georgia Green’ and the sectorial plant found in 2003. S₁ seed from both the one‐seeded pods as well as normal two‐seeded pods were planted from the sectorial plant. Relative DNA content was measured by flow cytometry on all plants. Results from the test showed that the coarse stem, thick leaf plants with poor fruit set were autooctoploids and had about twice the DNA content when compared with the normal sectorial branch and the allotetraploid peanut cultigen.