Length of the dark period affects flower opening and the expression of circadian-clock associated genes as well as xyloglucan endotransglucosylase/hydrolase genes in petals of morning glory (Ipomoea nil)

Auxin controls circadian flower opening and closure in the waterlily

“…In flowering plants, many flowers open during the day and close at night, exhibiting a 24-h circadian rhythm, which is known as Linné’s floral clock [ 1 ]. This circadian movement pattern serves as an environmental adaptation characteristic for creating an opportunity for pollination [ 1 ]; in Ipomoea nil , the flower-opening time is determined by the length of dark period [ 2 ]. However, without a light-dark switch period, flowers continue to display a rhythm in opening and closing when in a complete light or dark environment using their “internal clock”, i.e.…”

“…Cell wall biogenesis has been implicated as a core event downstream of auxin regulations that determines anisotropic cell expansion during plant development including floral circadian movement. In Ipomoea nil, transcripts of xyloglucan endotransglucosylase/hydrolases (XTHs) encoding the genes InXTH1-InXTH4 in petals, which are involved in cell wall modification, were closely correlated with the rate of flower opening, further controlling plastic petal growth [ 2 ]. In the ‘Mitchell’ petunia, knockdown of cell-wall-associated β-galactosidases, which determine the galactose level among cell wall polysaccharides, severely reduces the flower-opening angle due to the disruption of petal integrity [ 19 ].…”

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

“…Receptor-like kinases regulate the signaling pathways involved in multiple developmental processes (Walker, 1994). For example, the protein phosphorylation/ dephosphorylation mediated by receptor-like kinases plays an important role in the initiation of carnation flower opening (Harada et al, 2010;Shinozaki et al, 2014). Leu-rich repeat receptor-like kinases PAN1 and PAN2 have been shown to promote polarization of subsidiary mother-cell divisions during stomatal development in maize (Cartwright et al, 2009;Zhang et al, 2012).…”

“…Cell wall extensibility is believed to be a limiting factor for petal expansion (Yamada et al, 2009b). The expressions of genes related to cell wall function such as those that encode xyloglucan endotransglucosylase/hydrolase and expansins are positively correlated with the petal growth during flower opening (Harada et al, 2011;Dai et al, 2012;Shinozaki et al, 2014). Hormones, including ethylene, gibberellins, and auxin, regulate petal growth and flower opening.…”

“…Prior to opening, osmotic solute levels are rapidly increased by breaking down polysaccharides (starch or fructan) into monosaccharides, combining with sugar uptake from the apoplast (Hammond, 1982;Yamane et al, 1991;van Doorn and van Meeteren, 2003;Yamada et al, 2009a). Increased osmotic pressure contributes to the reduction of petal water potential, which facilitates water influx into the cells, and thus results in cell enlargement (Shinozaki et al, 2014). Cell wall extensibility is believed to be a limiting factor for petal expansion (Yamada et al, 2009b).…”