Altered Glycoflavone expression in induced Autotetraploids of Phlox drummondii

The effects of colchicine induced autotetraploidy on non-anthocyanin flavonoid expression were determine for 15 cultivars of Phlox drummondii and for the naturally occuring P. drummondii ssp. mcallisteri. Collectively, the taxa express a total of nine glycoflavonoid derivatives (C, O-diglycosides or di-C-glycosides) of either apigenin or luteolin. The autotetraploids of 14 cultivars and those of the natural subspecies exhibit altered glycoflavone profiles relative to their respective diploid sources. The qualitative alternations in the cultivars may be grouped into three phenotypic categories: (1) the expression of novel glycoflavones, (2) the absence of diploid glycoflavones, and (3) the deregulation of tissue-specific glycoflavone production. Alterations in mcallisteri autotetraploids include only the latter two categories. Each of the novel compounds is otherwise expressed among other diploid cultivars or in other wild P. drummondii subspecies. Quantitatively, the phenolic content of most autotetraploid flowers is significantly greater than in respective diploid flowers. However, on a dry weight basis, phenolic titre in comparable 4n and 2n floral or leaf tissues is not significantly different. Floral tissues express from 5 to 10 times the phenolic titre of leaves. The results are discussed in terms of the possible origins of novel flavonoids in natural polyploid Phlox species.