Tetraploidy induction enhances morphological, physiological and biochemical characteristics of wallflower (Erysimum cheiri (L.) Crantz)

•Polyploidization in wallflower created tetraploid Erysimum cheiri (2n = 4x = 24).•The best chromosome doubling result obtained by 150 mgl−1 oryzalin for 36 h.•The 4x wallflower had more flowers, longevity, size and flowering duration.•Anthocyanin and sugars of 4x plants were increased by 56% and 140%, respectively.•Tetraploids’ cytokinin, salicylic acid, jasmonic acid and abscisic acid increased. Wallflower (Erysimum cheiri (L.) Crantz is one of the most important bedding flowers and potted plants in the floriculture industry. Its widespread cultivation is hindered due to self-incompatibility and limited breeding. The present study was conducted to investigate the effects of polyploidy induction on different characteristics of wallflower. Seeds were treated with colchicine (0, 0.5, 0.75 and 1%) (w/v) and oryzalin (0, 50, 100 and 150 mgl−1) along various exposure times (24, 36 and 48 h). The highest tetraploidy induction (53%) was seen in 150 mgl−1 oryzalin treatment for 36 h. The chromosome doubled plants indicated increase in trichome number, pollen size, stomata size and number of chloroplasts in the stomata guard cells, while stomata density and pollen number were decreased. The new tetraploid induced wallflowers showed compact growth habit with shorter internodes and roots, while leaves were bigger (60%) and purplish, flowering period was prolonged (65%), and flowers showed greater longevity (41%), diameter (47%) and number (78%), compared to diploid controls. Their anthocyanin and total soluble solids contents were increased by 56% and 140%, respectively. UPLC-MS analysis indicated that phytohormone contents of Ze, SA, JA and ABA were significantly increased in the tetraploid induced plants than diploid controls, while IAA, GA3 and BR were less accumulated. The new ornamental features developed for the first time in wallflower proves that polyploidization is a promising tool to introduce a commercial flowering pot plant cultivar and a new genetic resource for future breeding programs.