Phytoremediation is a natural soil depollution approach whereby plant species are used to absorb and accumulate toxic metals such as lead. However, phytoremediation can be affected by plant sensitivity to high concentrations of heavy metals that reduce plant phytoremediation efficiency. To overcome this drawback, and to produce tolerant plants, the somaclonal variation technique is a tool of choice to introduce genetic variations in plant cells cultured in vitro under optimized caulogenesis protocols. Using combinatory concentrations of three phytohormones (benzylaminopurine “BAP”, gibberellic acid “GA₃”, and 2,4-dichlorophenoxyacetic acid “2.4-D”), we applied a caulogenesis protocol in Populus nigra under lead nitrate [Pb(NO₃)₂] stress conditions and selected from the resulting somaclones those that tolerate an optimal combinatory concentration of the three phytohormones. By applying small composite design (SCD), response surface method (RSM) and desirability function (D), we found that the combinatory concentrations of BAP at 6.66 µM; GA3 at 0.38 µM; and 2,4-D at 11.36 µM were optimal for poplar caulogenesis on a culture medium containing 274.40 mg/L of Pb(NO₃)₂. Although Pb(NO₃)₂ inhibited caulogenesis, 2,4-D attenuated the inhibitory effect of lead on callus recovery. BAP, in turn, attenuated the inhibitory effects on bud induction and bud number of these plants. These results suggest that poplar caulogenesis can be optimized mathematically under heavy metal stress conditions in view of breeding stress tolerant somaclones.

植物修复是一种自然的土壤污染方法，利用这种方法植物物种可以吸收和积累铅等有毒金属。但是，植物对高浓度重金属的敏感性会影响植物的修复，降低植物的植物修复效率。为了克服此缺点并生产耐受植物，体细胞克隆变异技术是在优化的caulogenesis协议下在体外培养的植物细胞中引入遗传变异的一种选择工具。使用组合浓度的三种植物激素（苄基氨基嘌呤“ BAP”，赤霉素“ GA ₃ ”和2,4-二氯苯氧乙酸“ 2.4-D”），我们在硝酸铅[Pb（NO ₃）]下的黑杨中应用了致病性方案。₂胁迫条件并从产生的体细胞激素中选择那些能够耐受三种植物激素最佳组合浓度的菌体。通过应用小型复合设计（SCD），响应面法（RSM）和合意函数（D），我们发现BAP的组合浓度为6.66 µM；GA3为0.38 µM；和11.4 µM的2,4-D最适合在含有274.40 mg / L Pb（NO ₃）_2的培养基上杨树的致密作用。尽管Pb（NO ₃）₂2，4-D减弱了铅对愈伤组织恢复的抑制作用。BAP反过来减弱了对这些植物的芽诱导和芽数的抑制作用。这些结果表明，鉴于繁育耐胁迫的体细胞无性系的繁殖，可以在重金属胁迫条件下数学优化杨树的发生。