Poster: Root biology
Abs #
693: Identification of two auxin response factor genes related to adventitious root formation of Mango (Mangifera indica L.) cotyledon sections
Adventitious root formation is a key step in vegetative propagation of fruit trees. Rooting from the regenerated shoots of mango is difficult. In this study, we described different capability of adventitious root formation between sections of cross and longitudinal cuts in mango cotyledon, and identified two auxin response factor genes (ARFs), MiARF1 and MiARF2, related to the root formation.
Adventitious roots could be induced from cross cut surfaces (proximal cut surfaces, PCS, which faced to embryo axis) in mango cotyledon under culturing for 21 days on agar medium without additional nutrients and plant growth regulators, but there were no roots to be formed both from the opposite surfaces of this cuts (distal cut surfaces, DCS) and the longitudinal cut surfaces (LCS). IBA strongly promoted the rooting of PCS, however no similar effect was observed on LCS and DCS. TIBA, an auxin transport Inhibitor, significantly inhibited the rooting and IBA could counteract the effects of TIBA. The roots were originally produced from the cut ends of the vascular strands .Two full length cDNA for the root formation were identified by means of RACE from the forward subtracted cDNA library. They were designated as Mangifera indica ARF 1( MiARF1: AY255705) and MiARF2: AY300808, since their deduced amino acid showed identifiable homologs with ARF2 of Arabidopsis. The majority of DBD between MiARF2 and MiARF1 was identical, but MiARF2 lacked a carboxyl-terminal domain that contains the conserved motifs III and IV. Virtual Northern blot indicated that expression of MiARF2 was specific for the rooting tissue of cotyledon sections and the MiARF1 could expressed both in the rooting tissue and non-rooting tissue. Above two genes will be investigated for their exact function in later study.
