ARS | Publication request: Confirmation of hybrid origin of Cyrtanthus based on the sequence analysis of internal transcribed spacer

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 2012
Publication Date: October 7, 2012
Citation: Lee, A.K., Hong, J., Bauchan, G.R., Park, S.H., Joung, Y.H. 2012. Confirmation of hybrid origin of Cyrtanthus based on the sequence analysis of internal transcribed spacer. Scientia Horticulturae. 144:153-160.

Interpretive Summary: The genus Cyrtanthus is native to South Africa with waxy tubular white, orange, and red flowers formed as clusters at the tip. Cyrtanthus elatus and C. sanguineus have been cultivated for many years. A new hybrid with a flower shape intermediate between C. elatus and C. sanguineus or similar to C. elatus which produces flowers easily would be desirable for potted plant use. Therefore, it would be ideal to combine the free flowering characters inherited from C. sanguineus and multiple flowers (4 to 5 flowers) and a strong flowering stem from C. elatus by interspecific hybridization. The objectives of this study were to create interspecific hybrids between Cyrtanthus elatus and C. sanguineus and to confirm the hybrid origin of the progeny based on morphological characters and molecular markers. The hybrid origin could not be confirmed based on the morphological characteristics of flowers, the tip of the leaves, and cell structure or surface images of both the upper and lower leaf surface from the low temperature-scanning electron microscopy. However, based on DNA marker analysis, the hybrid origin was confirmed. The hybrids can be used by the plant geneticists to improve the flower form, stem strength and increase the numbers of flowers for Cyrtanthus which will benefit the florist industry.

Technical Abstract: The objectives of this study were to create interspecific hybrids between Cyrtanthus elatus and C. sanguineus and to confirm the hybrid origin of the progeny based on morphological characters and using molecular markers. The tip of the leaves, the shape and size of cells, and stomata distribution in abaxial and adaxial surface of leaf epidermis were analyzed by low temperature scanning electron microscope (LT-SEM). Molecular markers generated from random amplification polymorphic DNA (RAPD) and single nucleotide polymorphisms (SNPs) analysis of internal transcribed spacer 1 and 2 of rRNA gene (ITS 1, 2) were also analyzed to confirm hybrid status. Putative C. elatus × C. sanguineus hybrid A 3 resembled C. elatus and C. sanguineus 'Pringle Bay' (PB) × 'Fred Meyer' (FM) B 23 and was similar to C. sanguineus at flowering. However, the hybrid origin of hybrid A 3 could not be confirmed based on the morphological characteristics of flowers, the tip of the leaves, and cell structure and surface images in both abaxial and adaxial images of LT-SEM. Based on RAPD markers, putative hybrid A 3 and other putative hybrids that did not flower (A 4, A 5, A 13 and D 39, D 40, and D 42) can be considered as a hybrid based on the presence of both species-specific bands for parental taxa. SNP markers of ITS 1, 2 region also revealed that other putative hybrids of A and D that did not flower during the evaluation can be interspecific hybrids of C. elatus and C. sanguineus. Therefore, the use of SNP markers of ITS 1, 2 is considered a more accurate tool to characterize hybrid origin than morphological characteristics and RAPD markers.