Identification and genetic characterization of a gibberellin 2-oxidase gene that controls tree stature and reproductive growth in plum

Abstract

Several dwarf plum genotypes (Prunus salicina L.), due to deficiency of unknown gibberellin (GA) signalling, were identified. A cDNA encoding GA 2-oxidase (PslGA2ox), the major gibberellin catabolic enzyme in plants, was cloned and used to screen the GA-deficient hybrids. This resulted in the identification of a dwarf plum hybrid, designated as DGO24, that exhibits a markedly elevated PslGA2ox signal. Grafting ‘Early Golden’ (EG), a commercial plum cultivar, on DGO24 (EG/D) enhanced PslGA2ox accumulation in the scion part and generated trees of compact stature. Assessment of active GAs in such trees revealed that DGO24 and EG/D accumulated relatively much lower quantities of main bioactive GAs (GA1 and GA4) than control trees (EG/M). Moreover, the physiological function of PslGA2ox was studied by determining the molecular and developmental consequences due to ectopic expression in Arabidopsis. Among several lines, two groups of homozygous transgenics that exhibited contrasting phenotypes were identified. Group-1 displayed a dwarf growth pattern typical of mutants with a GA deficiency including smaller leaves, shorter stems, and delay in the development of reproductive events. In contrast, Group-2 exhibited a ‘GA overdose’ phenotype as all the plants showed elongated growth, a typical response to GA application, even under limited GA conditions, potentially due to co-suppression of closely related Arabidopsis homologous. The studies reveal the possibility of utilizing PslGA2ox as a marker for developing size-controlling rootstocks in Prunus.

Mechanism of internal browning of pineapple: The role of gibberellins catabolism gene (AcGA2ox) and GAs

“…These processes include fruit growth21, underground growth19, seed germination, and vegetative and reproductive transitions20. Dwarfing is the most typical phenotype of plants overexpressing GA2oxs , such as AtGA2ox7 and AtGA2ox8 in Arabidopsis and tobacco17, poplar PtaGA2ox1 16 and PtGA2ox5 20 in poplar trees, spinach SoGA2ox3 in Nicotiana sylvestris 30, plum PslGA2ox in Arabidopsis 31, and grapevine VvGA2ox genes in Arabidopsis 32. However, apart from morphological changes, there has been no report showing what happens to the plants or plant organs that no longer grow when GA2ox expression is upregulated.…”

Plum Fruit Development Occurs via Gibberellin–Sensitive and –Insensitive DELLA Repressors

“…Gibberellin (GA) is an essential hormone involved in diverse biological processes, leading to correct plant growth and development [5–8]. In tree fruit species, the proper establishment of reproductive growth is dependent on coordinated levels of GA at the appropriate developmental stages [9–11]. Application of GA resulted in visible improvement of fruit quality traits in terms of size, weight and many other characteristics [12–13].…”

“…Application of GA resulted in visible improvement of fruit quality traits in terms of size, weight and many other characteristics [12–13]. Conversely, mutant fruits with inadequate quantities of GA exhibited a series of distortions in floral development and general reproductive growth events [1–2, 9, 14]. Although the potential impact of GA in coordinating fruit development processes has already been acknowledged [15–18], the mechanism by which these effects are achieved is still largely unknown.…”

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

“…), flowering was significantly reduced following the application of GA 3 during flower bud induction (Gonzalez-Rossia et al, 2006;Reig et al, 2011). PslGA3ox and PslGA2ox encode key enzymes that promote GA biosynthesis and deactivate GAs respectively, in P. salicina 'Early Golden' (El-Sharkawy et al, 2012. It is possible that these genes are also important for 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.…”