Characterization of gibberellin-signalling elements during plum fruit ontogeny defines the essentiality of gibberellin in fruit development

Abstract

Fruit growth is a coordinated, complex interaction of cell division, differentiation and expansion. Gibberellin (GA) involvement in the reproductive events is an important aspect of GA effects. Perennial fruit-trees such as plum (Prunus salicina L.) have distinct features that are economically important and provide opportunities to dissect specific GA mechanisms. Currently, very little is known on the molecular mechanism(s) mediating GA effects on fruit development. Determination of bioactive GA content during plum fruit ontogeny revealed that GA1 and GA4 are critical for fruit growth and development. Further, characterization of several genes involved in GA-signalling showed that their transcriptional regulation are generally GA-dependent, confirming their involvement in GA-signalling. Based on these results, a model is presented elucidating how the potential association between GA and other hormones may contribute to fruit development. PslGID1 proteins structure, Y2H and BiFC assays indicated that plum GA-receptors can form a complex with AtDELLA-repressors in a GA-dependent manner. Moreover, phenotypical-, molecular- and GA-analyses of various Arabidopsis backgrounds ectopically expressing PslGID1 sequences provide evidence on their role as active GA-signalling components that mediate GA-responsiveness. Our findings support the critical contribution of GA alone or in association with other hormones in mediating plum fruit growth and development.

The KNOTTED-like genes of peach (Prunus persica L. Batsch) are differentially expressed during drupe growth and the class 1 KNOPE1 contributes to mesocarp development

“…Briefly viewing at the peach GA expression trends, the PpGA3ox1 kinetics, made of a peak before fruit set and subsequent repression in pericarp (Fig. 6A) recalled that of GA3ox1 of plum and tomato [73,74]. The PpGA20ox1 undetected mRNA in drupe was consistent with RNA-seq data (Table 4) and recalled the absence of GA20ox1 expression in silique (Arabidopsis eFP Browser) and grape berry [75]; however, the tomato GA20ox1 transcription in pericarp [73,76] implies the occurrence of species-related regulatory mechanisms.…”

“…GA1, GA4, GA3 produced by the GA3OX enzyme and the powerful seedy GA32) could not be quantified [78]. In plum fruit, GA feedback mechanisms [79] were evoked to (partially) explain the association of GA3ox1 low expression with high GA1 and GA4 contents [74]. The low/S1 and high/S2 transcription of PpGA3ox1 might reflect this feedback regulation consistently with the high/S1 and low/S2 GA activity reported in peach fruit [77].…”

TIR1-like auxin-receptors are involved in the regulation of plum fruit development

“…In flowers, auxin specifies the site of floral primordium initiation and regulates floral organogenesis and patterning (Reinhardt et al , 2000; Cheng and Zhao, 2007). Post-fertilization, an interaction between auxin and gibberellin triggers fruit-set, the term given to the onset of rapid cell division necessary for early embryo development and fruiting structure enlargement (de Jong et al , 2009 a ; El-Sharkawy et al , 2014). In both berry- and stone-fruit, auxin has also been shown to be important during the immature fruit development and ripening processes (Miller et al , 1987; Agustí et al , 1999; Jones et al , 2002; El-Sharkawy et al , 2010, 2012; Seymour et al , 2013).…”

“…ASK1 and AtIAA7 sequences were cloned into the BglII-BamHI and XhoI-BamHI sites, respectively, of the pSAT1- C vector containing C-terminal YFP (CY). The different combinations of constructs encoding NY and CY at similar concentrations were mixed and then co-transfected into protoplasts obtained from suspension-cultured tobacco BY-2 cells in the presence of 100 µM IAA, as previously described (El-Sharkawy et al , 2014). Empty BiFC vectors (NY/CY), (NY:gene /CY) and (NY/CY:gene) were used as negative controls.…”

Effect of bending and the joint tree training system on the expression levels of GA3- and GA2-oxidases during flower bud development in ‘Kiyo’ Japanese plum

“…The amplification signal was measured with an Mx3000P TM Real-Time PCR System (Stratagene, CA, USA) using SYBR Premix Ex Taq TM II (Takara, Shiga, Japan). Gene-specific forward (5 -CATGTGGTCTGAGGGCTTCACTAT-3 ) and reverse -Sharkawy et al, 2012-Sharkawy et al, , 2014. Data were shown as the mean ± SE of three biological replicates.…”