Resistance to iron deficiency is mediated through rhizosphere acidification and ferric chelate reductase activity in Pyrus betulaefolia.

Iron (Fe) deficiency stress seriously impacts the yield and quality of pear fruit. Nevertheless, the mechanism of Fe absorption in pears (Pyrus betulaefolia) remains unclear. ARFs are a class of transcription factors that are widely involved in plant stress response. However, their function in iron absorption in pears remains unknown. In this study, we identified an auxin response factor in P. betulaefolia (PbeARF2) which was significantly induced by Fe deficiency stress. The Fe absorption capacities of PbeARF2 overexpressed Arabidopsis and P. betulaefolia seedlings were significantly enhanced. Compared to wild type (WT) plants, PbeARF2 overexpressed plants showed significantly enhanced rhizosphere acidification and ferric chelate reductase (FCR) activity. Furthermore, we found that PbeARF2 can activate the expression of PbeAHA12 and PbeFRO2 by directly binding to the promoters of these two genes. In conclusion, this study reveals a novel mechanism of Fe absorption in P. betulaefolia regulated by PbeARF2, and provided an important and new theoretical basis for the genetic improvement of Fe deficiency resistance in pears rootstock.