リンゴの根におけるリン酸修飾バイオ炭とAMの相乗効果によるCd蓄積とリン利用可能性の調節を介した細胞死の軽減

The safe disposal of apple pruning waste and mitigation of cadmium (Cd) toxicity in orchards are pressing environmental challenges. This study developed a synergistic strategy using phosphate-modified carbonized apple branches (PCAB) and arbuscular mycorrhizal (AM) fungi to immobilize Cd and reduce its uptake in apple trees. Compared to unmodified carbonized apple branches (CAB), PCAB exhibited a 1.35-fold higher Cd^2 + adsorption capacity and was more effective in converting soil acid-soluble Cd into stable residual fractions. The combination of PCAB and AM fungi (PCAB+AM) was most effective, enhancing AM root colonization by over 200 % under Cd stress. This synergy increased rhizosphere available phosphorus by 128 % and the proportion of labile P by 50 %, while reducing bioavailable Cd to less than half of that in CAB+AM treatment. Consequently, PCAB+AM minimized root Cd²⁺ influx to 31 % of the control, reduced leaf Cd concentration by 86 %, and decreased Cd translocation factor by 66 %. This treatment also more effectively alleviated Cd-induced oxidative stress and cell death, downregulating key apoptosis genes (MhVPEγ/MhBAX1) and VPEγ activity. Our findings demonstrate that the PCAB-AM combination creates a protective rhizosphere barrier, offering a sustainable waste-to-wealth solution for Cd-contaminated orchards.