Gibberellins (GA) are plant hormones that control diverse aspects of plant growth and development. Gibberellin 2-oxidase (GA2ox) plays a direct role in determining the levels of bioactive GAs by catalyzing bioactive GAs or their immediate precursors to inactive forms.

In a recent study published inFrontiers in Plant Science, Prof. XU Zengfu and his team of Xihsuangbanna Tropical Botanical Garden (XTBG) isolated JcGA2ox6 and analyzed its function in transgenic Arabidopsis and Jatropha. They found that overexpression of JcGA2ox6 had a significant impact on plant growth and development.

The researchers used a combined reverse transcriptase-polymerase chain reaction (RT-PCR) strategy to isolate JcGA2ox6 cDNA from Jatropha. They performed a qRT-PCR analysis with the total RNAs extracted from various tissues of adult plants, in order to investigate the expression pattern of JcGA2ox6 in Jatropha. The expression profile showed that JcGA2ox6 was almost constitutively expressed in adult Jatropha.

They further found that overexpression of JcGA2ox6 in Arabidopsis caused a dwarf phenotype with late flowering, smaller flowers, shorter siliques and smaller seeds. Overexpression of JcGA2ox6 in Jatropha caused a dwarf phenotype with small dark-green leaves and affected flower, fruit and seed development.

The transgenic Arabidopsis and Jatropha overexpressing JcGA2ox6 demonstrated the GA-deficient phenotype of dwarfism. However, transgenic Jatropha showed an unexpected phenotype of fewer inflorescences and flowers. Even the seed weights and oil contents were decreased.

Although the expected phenotype of vigorous reproductive growth was not exhibited in transgenic Jatropha, the dwarf trait may allow for dense field plantation and increase the efficiency of fruit collection in Jatropha plantations.

The results indicated that overexpression of JcGA2ox6 had a great impact on the vegetative and reproductive growth of transgenic Jatropha.