Amiprophosmethyl-treatment for polyploidisation in Lobelia
Lobelia is well established as ornamental plant since the 17th century. During the last decades, breeding mainly based on hybridization and resulted in an increasing number of cultivars. Polyploidisation in general is known for its essential contribution to an increased horticultural and ornamental value. In the assortments of Lobelia erinus diploid, tetraploid and hexaploid cultivars are described and linked to different quality levels. The octoploid level is not yet established for cultivars but expected to increase the ornamental value of L. erinus cultivars further. Efficient mutation methods are necessary to accelerate the breeding process. Therefore, the objective of this work was to evaluate the mutagenic effect of in vivo amiprophosmethyl (APM) application on the diploid L. cuneifolia and on L. erinus cultivars with different ploidy levels (tetraploid 'Africo White', hexaploid 'Africo Sky'). Axillary buds of ten plants per variant were treated with 100 and 200 ppm APM, respectively. Leaves of the shoots developed from the treated buds were evaluated weekly regarding morphological differences. Segments (ca. 1 cm2) of putatively mutated leaves were disinfected and cultivated in vitro on a modified MS medium with 1 mg L‑1 2,4-D as growth regulator. After 7-14 days the segments formed callus and were sub-cultured two to three weeks later on regeneration media (MS supplemented with 1 g L‑1 activated charcoal or 1 mg L‑1 BA) to regenerate adventitious shoots. The regeneration potential differed among the genotypes. Isolated adventitious shoots with at least three nodes were cultivated on a modified MS medium with 1 g L‑1 activated charcoal for rooting. The plants were acclimatised and transferred into the greenhouse. From all treated genotypes and variants of APM concentrations plants with doubled ploidy level were regenerated. These plants are fertile and can therefore also be used for interspecific and interploid cross-breeding.
Wernicke, M., Pinker, I., Wiedemann, M. and Olbricht, K. (2020). Amiprophosmethyl-treatment for polyploidisation in Lobelia. Acta Hortic. 1283, 153-160
adventitious shoots, callus culture, diploid, dodecaploid, octoploid, ploidy breeding, tetraploid