Expression analysis of reciprocal grafted of near-isogenic soybean lines under iron stress

Iron stress response signaling between roots and shoots is not well understood in soybean. While studies have identified early responses to iron stress (as early as 30 minutes) the signaling pathway has not been well documented. In this study we used near-isogenic lines (Clark [Clk] and IsoClark [Iso]) to create four types of grafts (scion/roots), two homografts (Clk/Clk and Iso/Iso) and two heterografts (Clk/Iso and Iso/Clk). In hydroponics we subjected half the grafted seedlings to iron stress and collected leaf and root tissue after 30 and 120 minutes after iron stress; we extracted and sequenced RNA from the tissue samples. We identified differentially expressed genes and differences in expression patterns between grafting combinations. These results support the hypothesis that the physiological and molecular iron stress response is determined by the root genotype.