Figure 2.

MdMAPKKK1 overexpression caused cell death. (a) Nicotiana leaves infiltrated with Agrobacterium harboring pCAMBIA1300-MdMAPKKK1 exhibited tissue necrosis 48 h after infiltration, but those infiltrated with Agrobacterium harboring pCAMBIA1300-MdMAPKKK1^K360M did not. (b) MdMAPKKK1 overexpression led to H₂O₂ accumulation. Left: Nicotiana leaves 24 h after infiltration with GV3101 containing pCAMBIA1300 or pCAMBIA1300-MdMAPKKK1 plasmids; right: Nicotiana leaves were stained with 3, 3′-diaminobenzidine (DAB) 24 h after infiltration. (c) The % live cells after induction of MdMAPKKK1 expression by β-estradiol. Control: the calli treated with 0.1% ethanol (β-estradiol solvent). Induction: the calli treated with 5 μM β-estradiol. **, p < 0.01. (d) MdMAPKKK1 expression-induced apple cell death. Live cells were stained with fluorescein diacetate (FDA). WT: wild type apple cell from ‘Orin’ calli; EV: apple cells transformed with pER8 vector; OE: apple cells transformed with pER8-MdMAPKKK1. MdMAPKKK1 expression was induced by 5 μM β-estradiol. The scale bars represent 275 nm.