Breeding Long Vase Life by Crossing and Selection for Five Generations in Dahlia (<i>Dahlia variabilis</i>) Cut Flowers, and Selection of Fourth-Generation Line 003-15 with Ultra-Long Vase Life

Abstract

Genetic improvement of flower vase life is an important breeding target for ornamental plants. As the vase life of cut dahlia (Dahlia variabilis) flowers is very short, we initiated a conventional crossbreeding research program in 2014 to improve it. We evaluated the vase life of dahlia seedlings during summer (from July to early September) to develop dahlias that grow and bloom under high temperatures and have excellent vase life for Japanese summer conditions. Crossing and selection over five generations greatly improved vase life. The mean vase life increased from 4.4 days in the 1st generation, derived from 22 parental cultivars, to 8.0 days in the 5th generation, a net increase of 3.6 days. Mean vase life increased significantly by 1.6 days from the 4th to the 5th generation, indicating continued improvement. The mean vase life of the 12 lines selected from the 3rd and 4th generations ranged between 6.0 and 15.9 days in distilled water and from 7.8 to 14.6 days in GLA solution (10 g•L −1 glucose, 0.5 mL•L −1 CMIT/MIT [isothiazolinone derivatives], and 50 mg•L −1 aluminum sulfate). Vase life was further extended by 0.5 to 4.0 days using 6-benzylaminopurine (BA) sprays compared to GLA alone. In particular, the 4th-generation line 003-15 vase life was 13.8 to 15.9 days (2.5× that of 'Kamakura', a leading white dahlia cultivar in Japan) in distilled water, 12.0 to 14.6 days (1.8× to 2.2×) in GLA, and 13.9 to 15.3 days (1.7× to 1.9×) in GLA+BA in winter and spring. Cut flowers of line 003-15 harvested under high temperatures in July-August and at 28°C with GLA treatment also had long vase life. The pedigree of line 003-15 suggests that genes related to long vase life derived from 'Micchan' (with a long vase life) may have accumulated or duplicated in line 003-15. Finally, four selected lines, including 003-15, had high ethylene sensitivity, as 10 μL•L −1 ethylene treatment caused petal abscission in 2.0 to 2.8 days.

The genomes of Dahlia pinnata, Cosmos bipinnatus, and Bidens alba in tribe Coreopsideae provide insights into polyploid evolution and inulin biosynthesis

“…D. pinnata and C. bipinnatus are popular flowers all over the world [ 3 , 62 , 63 ], and B. alba is a traditional medical plant, although it is also recognized as an invasive plant [ 60 ]. The genomic resources of D. pinnata and C. bipinnatus presented in this study will promote the studies on regulating mechanisms of flower shapes, colors, and senescence and benefit the flower industry by breeding more popular and long-vase life cultivars of flowers.…”