Growth regulating factor (GRF) binds to the QLQ (Gln, Leu, Gln) domain at the Nterminal of GRF interacting factor (GIF), acting as a transcriptional coactivator and playing important roles in plant growth, development and resistance to stresses. To date, no comprehensive identification and analysis of GRF and GIF gene families have been reported in Isatis indigotica Fort.. In this study, the gene structures, conserved motifs, physicochemical properties, chromosomal localizations, cisacting elements, evolutionary relationships and expression patterns were systematically analyzed. The results showed that there were 10 IiGRFs distributed on 5 chromosomes, and 4 IiGIFs on 2 chromosomes. IiGRFs and IiGIFs could be divided into 4 and 2 subfamilies, respectively. IiGRFs has two pairs of segmental duplication genes, but no tandem duplication genes. Moreover, IiGRFs (19.14fold) and IiGIFs (8.0fold) had the highest expression levels in young leaves and stems, compared with those in roots. The upstream regions of IiGRFs and IiGIFs contained more photo and MeJA hormone responsive elements, responding to shade and hormone stresses. Furthermore, the correlation analysis showed that IiGRF4 and IiGIF2, IiGRF4 and IiGIF4, and IiGRF4 and IiGIF3 were coexpressed with each other, which suggested that these paired genes could function together. The findings provided the more fundamental information on IiGRFs and IiGIFs, and laid good foundations for their further functional research in I. indigotica.
Keywords: Isatis indigotica Fort., GRF, GIF, gene family, expression pattern
