An AGAMOUS-like factor is associated with the origin of two domesticated varieties in Cymbidium sinense (Orchidaceae)

Abstract

Cymbidium has been artificially domesticated for centuries in Asia, which produced numerous cultivated varieties. Flowers with stamenoid tepals or those with multiple tepals have been found in different species of Cymbidium; however, the molecular basis controlling the formation of these phenotypes is still largely unknown. Previous work demonstrated that AGAMOUS/AG lineage MADS genes function in floral meristem determinacy as well as in reproductive organs development in both dicots and monocots, indicating a possible relationship with the origin of two flower varieties in Cymbidium. Here, we characterized and analyzed two AG lineage paralogues, CsAG1 and CsAG2, from Cymbidium sinense, both of which were highly expressed in the gynostemium column of a standard C. sinense. Interestingly, we detected ectopic expression of CsAG1 rather than CsAG2 in all floral organs of a stamenoid-tepal variety and significant down-regulation of CsAG1 in a variety with multiple tepals. Over-expression of CsAG1 in wild type Arabidopsis resulted in petal-to-stamen homeotic conversion, suggesting a conserved C-function of CsAG1 in the development of Cymbidium flower. Altogether, our results supported a hypothesis that disruption of a single AG-like factor would be associated with the formation of two domesticated varieties in C. sinense.

Identification, characterization and functional analysis of AGAMOUS subfamily genes associated with floral organs and seed development in Marigold (Tagetes erecta)

“…Remarkably, in Arabidopsis, ectopic expressions of TeAG1 and TeAGL11–1 resulted in short siliques, low seed setting rate, and sepal retainment at the bottom of mature siliques. This result was consistent with the finding reported in Cymbidium [ 49 ]. The expression analysis of endogenous gene STK suggested that short siliques with low seed setting rate might be correlated with the increased STK expression level in 35S:TeAG1 lines, while the short siliques with low seed setting rate might be associated with the decreased STK transcript level in TeAGL11–1 transgenic lines.…”

Identification, Characterization and Functional Analysis of AGAMOUS Subfamily Genes Associated with Floral Organs and Seed Development in Marigold (Tagetes erecta)

“…Remarkably, ectopic expression of TeAG1 and TeAGL11-1 resulted in short siliques with low seed setting rate and persistence of sepals at the bottom of mature siliques in Arabidopsis. This is consistent with the data reported in C. sinense [43]. The expression analysis of endogenous gene STK in 35S:TeAG1 lines suggested that short siliques with low seed setting rate correlated with increase of STK expression level, while the short siliques with low seed setting rate may associate with the decrease of STK transcripts in TeAGL11-1 transgenic lines.…”

Identification, characterization and functional analysis of AGAMOUS subfamily genes associated with floral organs and seed development in Marigold (Tagetes erecta)

“…Remarkably, in Arabidopsis, ectopic expressions of TeAG1 and TeAGL11-1 resulted in short siliques, low seed setting rate, and sepal retainment at the bottom of mature siliques. This result was consistent with the nding reported in Cymbidium [49]. The expression analysis of endogenous gene STK suggested that short siliques with low seed setting rate might be correlated with the increased STK expression level in 35S:TeAG1 lines, while the short siliques with low seed setting rate might be associated with the decreased STK transcript level in TeAGL11-1 transgenic lines.…”