• ISSN 1008-505X
  • CN 11-3996/S
ZHI Yi-ming, CHEN Fang, LIU Xiao-man, XIAO Kai. Regulation effects of an auxin response gene in wheat (TaARF6) in mediating plant growth under conditions of normal growth and Pi deprivation[J]. Journal of Plant Nutrition and Fertilizers, 2016, 22(1): 85-93. DOI: 10.11674/zwyf.14510
Citation: ZHI Yi-ming, CHEN Fang, LIU Xiao-man, XIAO Kai. Regulation effects of an auxin response gene in wheat (TaARF6) in mediating plant growth under conditions of normal growth and Pi deprivation[J]. Journal of Plant Nutrition and Fertilizers, 2016, 22(1): 85-93. DOI: 10.11674/zwyf.14510

Regulation effects of an auxin response gene in wheat (TaARF6) in mediating plant growth under conditions of normal growth and Pi deprivation

  • 【Objectives】 Auxin response factors (ARFs) play a critical role in mediating transduction of auxin signaling and regulating expression of downstream auxin-responsive genes. In this study, an ARF type transcription factor gene referred to TaARF6 identified in a root suppression subtractive cDNA library that enriches the differentially expressed genes under Pi sufficiency as the basis was used to investigate molecular characterization of TaARF6 and its expression patterns under various Pi-supply conditions, as well as its functions in regulating plant phenotypes. The objective of this study was aimed to elucidate biological roles of TaARF6 in mediating plant growth features under the conditions of Pi sufficiency and Pi deficiency. 【Methods】The protein characterization of TaARF6 was predicted by the bioinformatics' tools. The seedlings of wheat (cv. Shixin 828) were cultured under the sufficient-and deficient-Pi conditions by a hydroponic approach and used to investigate the expression patterns of TaARF6 based on semi-quantitative RT-PCR. A DNA recombinant technique was adopted to construct the expression cassette integrating the TaARF6 open reading frame. The transgenic tobacco plants overexpressing TaARF6 were generated based on a genetic transformation approach mediated by Agobacterium-tumefaciens using the leaf discs as explants. Based on the culture methods of agar medium and hydroponic solution, the seedlings and plants of the transgenic Line 3 and Line 5 as well as wild type (WT) were cultured to determine the growth features and to assay the fresh and dry weights of roots and aboveground tissues under the conditions of Pi sufficiency and Pi deficiency.【Results】 1) TaARF6 encodes a transcription factor categoried into auxin response factor family and shares the conserved domains of ARF proteins in plants, such as the DNA binding domain and the auxin response domain. It shares a high identity to BdARF6 and OsARF6, two ARF family members in B. distachyon and rice, respectively, at the amino acid level. The expression analysis reveals that TaARF6 is significantly down-regulated by Pi deprivation in roots and leaves, and its expression in the above tissues is restored by a recovery treatment initiated by retransferring the Pi-deprived plants to normal-Pi condition. 2) Compared with the wild type, the tobacco seedlings and plants overexpressing TaARF6 are improved under both Pi sufficiency and Pi deficiency conditions. 3) Compared with the wild type, the fresh and dry weights in roots, stems and leaves, and in the whole plant of the tobacco seedlings and plants with overexpression of TaARF6 are increased under the conditions of both normal growth and Pi deprivation, and the lateral root numbers, lengths of the primary and lateral roots, root volume, leaf areas and the ratios of root weight to aboveground tissue weight are also increased.【Conclusions】Our results in this study confirm that TaARF6 encodes a typical auxin response factor, and its encoded protein contains distinct domains generally situated in ARFs. TaARF6 is significantly responsive to external Pi levels. Overexpression of TaARF6 can improve plant growth features, fresh and dry weights under the conditions of normal growth and Pi deprivation. Together, our investigation in this study suggests that TaARF6 plays critical roles in mediating plant growth and dry mass production under various Pi-supply conditions, which is possibly finished through its transcriptional regulating expression of the downstream auxin-responsive genes.
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