Fig. 1: The use of iaaM rootstock improves graft healing.

A One week after grafting, complete graft healing was observed in the WT/iaaM grafts, whereas only partially healed graft unions with obvious deeper gaps developed in the WT/WT grafts. B One week after grafting, the iaaM rootstock exhibited earlier root initiation and more and longer roots than the WT rootstock. C, D Two weeks after grafting, the WT/iaaM grafts (D) showed enhanced root biomass, more vigorous scion growth, and no lateral bud release compared with the WT/WT grafts (C). The arrows point to scions; Bar = 1 cm. E, F A microscopic analysis performed two weeks after grafting showed complete healing in the WT/iaaM grafts (F), whereas obvious gaps were found between the scion and rootstock in the WT/WT grafts (E). The arrows point to the graft junctions; Bar = 200 μm. (G) One week after longitudinal cutting, the WT stems produced little callus, and the split remained unhealed; in contrast, the cut iaaM stems completely healed, and a mass of callus cells filled the gap. H, I The iaaM stems contained more cambium and xylem cells (I) than the WT stems (H); Bar = 300 μm. J, K The xylem cells of the iaaM stems had thicker cell walls (K) than those of the WT stems (J); Bar = 100 μm. ca, cambium; co, cortex; pl, phloem; xm, xylem