Epigenetic variation in tissue cultured Gaura lindheimeri

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High levels of variability were observed in tissue cultured Gaura lindheimeri genotypes when flowered in situ. Tissue culture treatments for chromosome doubling (colchicine: 0, 0.25, 1.25 mM; trifluralin: 0, 15, 30 μM) were all highly variable for morphological traits. Experiment No. 1 tested the tissue culture protocols used. In the first control (C1), plantlets were subcultured continuously. Nodes were excised and placed on solid medium for the second control (C2). In the third control (C3), nodes were excised and put in liquid medium for 24 h at room temperature. The fourth control (C4) was the same as the third control except liquid cultures were moved to 4°C for 48 h after treatment at room temperature. Experiment No. 2 examined the stability of the variation. Representative plants with different traits were selected for clonal propagation and grown in a replicated trial in the greenhouse. Several morphological traits (flower size, leaf length:width ratios, petal length:width ratios, and flower color) were measured. All of the controls had as much variability as the treated plants. Flower size of the first flower for plant number 01G-02 was significantly different in C1 compared with C3, but not with C2 and C4. Plant number 443-1 (white) was more stable in the replicated trial for the flower size than plant number 01G-02 (pink). All traits measured for plant number 01G-02 were unstable; most flower colors and patterns reverted back to the original color of the non-tissue cultured plants. The somaclonal variation observed was epigenetic in nature, indicating changes in DNA methylation.