Tarenaya cultivars: genome size and genetic diversity

The spider flower, Tarenaya hassleriana (syn. Cleome spinosa), belongs to the family Cleomaceae, that originates in South America and is used as ornamental plant. Cultivar series were bred on a small scale, but showed low morphological diversity. The used gene pool and the hybridization steps carried out are largely unknown, but it is assumed that T. hassleriana was involved. Therefore, genome size as well as morphological and genetic diversity of seven generatively and ten vegetatively propagated cultivars were determined. Also T. boliviensis was included in the study. A field trial performed in 2021 at the Saxon State Office for Environment, Agriculture and Geology in Dresden, Germany, showed better flowering performance and overall impression for vegetatively propagated in comparison to the seed-propagated cultivars. To estimate the genetic distance, 168 individual bands from RAPD/dpRAPD analysis provided a clear distinction between T. boliviensis and the cultivars as well as between the groups of vegetatively and seed-propagated cultivars. Within the cultivar groups the genetic variation was found to be highly reduced. Three biological replicates of leaves and petals were measured with the flow cytometer CytoFLEX (Beckman Coulter). The 2C DNA contents were calculated using the internal standard tomato ‘Stupické’ and the software CytExpert 2.3. Mean 2C values could be distinguished into two main groups. Group 1 varied from 0.64 to 0.67 pg and included all generatively and three vegetatively propagated cultivars. Group 2 varied from 0.92 to 1.01 pg and consisted of seven cultivars and T. boliviensis. These results support further breeding and the enhancement of variability of ornamental Tarenaya.