Ectopic overexpression of wheat adenosine diphosphate-ribosylation factor, TaARF, increases growth rate in Arabidopsis.

Differential gene expression between hybrids and their parents is considered to be associated with heterosis. However, the physiological functions and possible contribution to heterosis of these differentially expressed genes are unknown. We have isolated one hybrid upregulated gene encoding putative wheat ADP-ribosylation factor, designated TaARF. In this study, real-time quantitative reverse transcription-polymerase chain reaction analysis indicated that the TaARF transcript was preferentially expressed in root, node and crown, and the accumulation of TaARF mRNA in hybrid was more than 1.5-fold higher than that in two parents. In order to understand possible roles of the putative wheat ARF gene, TaARF was overexpressed in Arabidopsis, and the transgenic plants were characterized. We show that ectopic overexpression of TaARF in Arabidopsis leads to increased leaf area, increased growth rate and earlier transition to flowering, suggesting that TaARF plays significant roles in growth and development. This study provides evidence demonstrating that TaARF plays important roles in growth and development and we speculate that the upregulated expression of this gene might contribute to the heterosis observed in wheat root and leaf growth.