Physiological Variation in Tissue Culture Regenerated Apomictic Paspalum dilatatum

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Summary Tissue culture techniques provide unique opportunities to introduce variability into vegetatively propagated or apomictic plants. We studied 45 regenerates of apomictic common dallisgrass ( Paspalum dilatatum Poir.) derived via tissue culture to search for variability in characteristics related to stress tolerance. Plants were grown in replicated field nurseries. Characteristics measured were heat tolerance as determined by both the solute leakage and tiller survival methods, leaf epicuticular wax content, and survival under severe water stress. In each test, one or more of the regenerates differed from common dallisgrass. In the solute leakage test, two entries had less damage than common, while seven were damaged more than common. In the tiller survival test, two entries were significantly lower in mortality than common dallisgrass. Three entries had better survival than common in the water stress test, while four entries were significantly higher in mortality. The range in wax values observed in the regenerates was relatively narrow. However, two entries were significantly higher in wax than common, but none were significantly lower. In several cases, some entries differed from common for more than one of the parameters tested, although the majority of the entries did not differ from and probably were similar to common dallisgrass. These findings demonstrate that somaclonal variation expressed in plants regenerated through tissue culture include basic physiological characteristics that influence drought and heat tolerance. Because these changes are in an obligate apomict, they are permanently fixed and will be expressed in subsequent generations.