Cloning, characterization, and expression of xyloglucan endotransglucosylase/hydrolase and expansin genes associated with petal growth and development during carnation flower opening

Abstract

Growth of petal cells is a basis for expansion and morphogenesis (outward bending) of petals during opening of carnation flowers (Dianthus caryophyllus L.). Petal growth progressed through elongation in the early stage, expansion with outward bending in the middle stage, and expansion of the whole area in the late stage of flower opening. In the present study, four cDNAs encoding xyloglucan endotransglucosylase/hydrolase (XTH) (DcXTH1–DcXTH4) and three cDNAs encoding expansin (DcEXPA1–DcEXPA3) were cloned from petals of opening carnation flowers and characterized. Real-time reverse transcription-PCR analyses showed that transcript levels of XTH and expansin genes accumulated differently in floral and vegetative tissues of carnation plants with opening flowers, indicating regulated expression of these genes. DcXTH2 and DcXTH3 transcripts were detected in large quantities in petals as compared with other tissues. DcEXPA1 and DcEXPA2 transcripts were markedly accumulated in petals of opening flowers. The action of XTH in growing petal tissues was confirmed by in situ staining of xyloglucan endotransglucosylase (XET) activity using a rhodamine-labelled xyloglucan nonasaccharide as a substrate. Based on the present findings, it is suggested that two XTH genes (DcXTH2 and DcXTH3) and two expansin genes (DcEXPA1 and DcEXPA2) are associated with petal growth and development during carnation flower opening.

Cell Division and Expansion in Petals during Flower Development and Opening in <i>Eustoma grandiflorum</i>

“…Numerous proteins and enzymes are required for cell expansion. Genes encoding expansin, which is involved in cell wall loosening, are expressed during flower opening of carnation (Harada et al, 2011), Mirabilis jalapa (Gookin et al, 2003), and Petunia hybrida (Zenoni et al, 2004), and xyloglucan endotransglycosylase/ hydrolase (XTH) activity is associated with the opening of sandersonia flowers (O'Donoghue et al, 2002). Recently, Ochiai et al (2013a) reported that the expression of expansin and XTH genes and their proteins increased during flower opening in Eustoma.…”

Preparation of a Xyloglucan Oligosaccharide Mixture from Tamarind Seed Gum and its Promotive Action on Flower Opening in Carnation Cultivars

“…XET activity and xyloglucan were able to be simultaneously localized in plant tissues according to fluorescence from wall-bound xyloglucan conjugated with XLLG-SR (sulforhodamine) by the action of XET (Vissenberg et al, 2000). Harada et al (2011) showed that XTH was actively involved in the expansion growth of petals of carnation flowers during flower opening. Moreover, by an in situ staining experiment of XTH activity using rhodamine-labelled XG9 in growing carnation petals, they showed that XET activity could transfer cleaved xyloglucan polymers to rhodaminelabeled XG9, which acted as an accepter substrate.…”

“…Laitinen et al (2007) showed that Gerbera hybrida had several XTH genes and their expression pattern during the development of ray flowers differed; some genes were up-regulated in the early stage and down-regulated in the late stage of petal development, and others vice versa. Recently, Harada et al (2011) cloned four cDNAs for XTH (DcXTH1-DcXTH4) from petals of opening carnation (Dianthus caryophyllus L.) flowers and examined the expression of their corresponding genes in floral and vegetative tissues of carnation plants with opening flowers, revealing that DcXTH2 and DcXTH3 are associated with petal growth and development during carnation flower opening.…”

Flower senescence: some molecular aspects

“…Moreover, the expansin gene, GgEXPA1 (Gibberellic acid responsive gene in gladiolus) has been reported to be expressed prominently during phases of active tepal expansion and cell elongation in stamen filaments, gynoecium styles and expanding leaves but not in tissues where expansion had ceased and senescence had been initiated (Azeez et al 2010). Recently, four cDNAs encoding xyloglucan endotransglucosylase/hydrolase (XTH) (DcXTH1-DcXTH4) and three cDNAs encoding expansin genes (DcEXPA1-DcEXPA3) have been cloned and characterized from petals of opening carnation flowers of which two XTH genes (DcXTH2 and DcXTH3) and two expansin genes (DcEXPA1 and DcEXPA2) have been reported to be associated with petal growth and development during flower opening (Harada et al 2011b). Moreover, the analysis of five transcripts (RhCG1, RhCG2, RhCG4, RhCG6 and RHAG1) from two rose cultivars ('Black magic' and 'Maroussia') by Hajizadeh et al (2011a) also revealed the presence of the transcripts that encode the products involved in cell wall expansion and degradation during senescence, e.g., RhCG6 has been found to share 65 % sequence similarity with the gene encoding apple β-galactosidase protein.…”