Chalcone Synthase and Flavonol Accumulation in Stigmas and Anthers of Petunia hybrida

Abstract

Flavonol aglycones are required for pollen germination in petunia (Petunia hybrida 1.). Mutant plants lacking chalcone synthase (CHS), which catalyzes the first committed step in flavonoid synthesis, do not accumulate flavonols and are self-sterile. l h e mutant pollen can be induced to germinate by supplementing it with kaempferol, a flavonol aglycone, either at the time of pollination or by addition to an in vitro germination system. Biochemical complementation occurs naturally when the mutant, flavonol-deficient pollen is crossed to wild-type, flavonoid-producing stigmas. We found that successful pollination depends on stigma maturity, indicating that flavonol aglycone accumulation may be developmentally regulated. Quantitative immunoblotting, in vitro and in vivo pollen germination, and high-performance liquid chromatographic analyses of stigma and anther extracts were used to determine the relationship between CHS levels and flavonol aglycone accumulation in developing petunia flowers. Although substantial levels of CHS were measured, we detected no flavonol aglycones in wild-type stigma or anther extracts. Instead, the occurrence of a conjugated form (flavonol glycoside) suggests that a mechanism may operate to convert glycosides to the active aglycone form.

Variation of Herbivore-Induced Volatile Terpenes among Arabidopsis Ecotypes Depends on Allelic Differences and Subcellular Targeting of Two Terpene Synthases, TPS02 and TPS03

“…Interestingly, TPS03 promoter activity was observed in pollen grains and resembles the recently reported expression of a valencene sesquiterpene synthase in the pollen of grape (Vitis vinifera) flowers (Martin et al, 2009). A pattern of constitutive expression in reproductive organs and induced expression in vegetative tissues has also been observed for Arabidopsis geranyllinalool synthase (TPS04/GES; Herde et al, 2008) in the formation of the volatile homoterpene TMTT and has been demonstrated for other genes involved in plant defense (Pollak et al, 1993;Hoegen et al, 2002;Stotz et al, 2009).…”

Antisense and Sense CHS cDNA Expressed by a Tapetum-specific Promoter Causes Partial Male Sterility in Transgenic Tobacco

“…It is likely that the reduction of CHS activity prevents development of fertile pollen grains because CHS is a key enzyme for flavonoid biosynthesis. It has been reported that the accumulation of the flavonols is observed in stigma, ovaries, pollen grains and pollen tubes [20][21][22] . Moreover, it has also been reported that flavonols stimulate development, germination, and pollen tube growth of tobacco [1].…”

A flavonol synthase gene GtFLS defines anther-specific flavonol accumulation in gentian

“…In maize, F3H transcript accumulation was coordinated with the appearance of flavonols in anthers (Daboo et al 1995). In addition, flavonol accumulation in petunia and potato were initiated by expression of CHS (Pollak et al 1993;van Eidik et al 1997). In gentian, it was demonstrated that two branches of the flavonoid biosynthetic pathway, namely flavonol biosynthesis in the anthers and flavone biosynthesis in the petals, are regulated by the spatial-specific expression of FLS and FNSII, respectively.…”

“…In maize, F3H transcript accumulation is coordinated with the appearance of flavonols in anthers (Daboo et al 1995). In contrast, flavonol accumulation in petunia and potato is initiated by CHS expression (Pollak et al 1993;van Eldik et al 1997). Similarly, the key enzymatic gene in flavonoid biosynthesis in anthers differs among plant species.…”

“…In anthers and pollen of petunia and maize, several flavonoid biosynthetic genes were isolated and characterized (Deboo et al 1995;Pollak et al 1993;van Tunen et al 1989van Tunen et al , 1990van Tunen et al , 1991. In maize, F3H transcript accumulation is coordinated with the appearance of flavonols in anthers (Daboo et al 1995).…”