Adventitious root (AR) development takes place in an intricate cellular environment. Reactive oxygen species (ROS) and antioxidant defenses, triggered by wounding in cuttings, can modulate this process. A comparative assessment of biochemical and anatomical parameters at critical rooting stages in hard- (Eucalyptus globulus Labill.) and easy- (Eucalyptus grandis W.Hill ex Maiden) to-root species was carried out. Microcuttings from seedlings were inoculated in auxin-free AR induction medium and, after 96 h, transferred to AR formation medium for a period of 24 h. Samples were collected upon excision (Texc) and at the 5th day post excision (Tform). Delayed xylem development, with less lignification, was recorded in E. globulus, when compared to E. grandis, suggesting lower activity of the cambium layer, an important site for AR development. Superoxide was more densely present around the vascular cylinder at both sampled times, and in greater quantity in E. globulus than E. grandis, declining with time in the former. Hydrogen peroxide was localized primarily along cell walls, more intensely in the primary xylem and phloem, and increased significantly at Tform in E. globulus. Ascorbate peroxidase (APX), superoxide dismutase (SOD), and catalase (CAT) activities were generally higher in E. grandis and varied as a function of time in E. globulus. Soluble guaiacol peroxidase (GPRX) activity increased from Texc to Tform in both species, whereas cell wall-bound GPRX activity increased with time in E. grandis, surpassing E. globulus. Flavonoid content increased with time in E. grandis and was higher than E. globulus at Tform. Principal component analysis showed that species- and time-derived differences contributed to almost 80% of the variance. Overall, data indicate that E. grandis shows higher cambium activity and tighter modulation of redox conditions than E. globulus. These features may influence ROS-based signaling and phytohormone homeostasis of cuttings, thereby impacting on AR development. Besides being players in the realm of AR developmental differences, the specific features herein identified could become potential tools for early clone selection and AR modulation aiming at improved clonal propagation of this forest crop.

不定根（AR）的发育发生在复杂的细胞环境中。由插条受伤引发的活性氧（ROS）和抗氧化防御可以调节这一过程。硬生根关键阶段生化和解剖参数的比较评估（蓝桉拉比尔。）和简单-（巨桉W.Hill ex Maiden）对根物种进行了研究。将幼苗的微插条接种到不含生长素的 AR 诱导培养基中，96 小时后，转移到 AR 形成培养基中 24 小时。在切除时(Texc)和切除后第5天(Tform)收集样品。木质部发育延迟，木质化较少，记录在蓝桉，相比之下巨桉，表明形成层的活性较低，而形成层是 AR 发育的重要部位。在两个采样时间，超氧化物在血管柱周围存在得更密集，并且在蓝桉比巨桉，前者随着时间的推移而下降。过氧化氢主要集中在细胞壁上，在初生木质部和韧皮部更强烈，并且在 Tform 处显着增加蓝桉。抗坏血酸过氧化物酶 (APX)、超氧化物歧化酶 (SOD) 和过氧化氢酶 (CAT) 活性通常较高巨桉并随着时间的变化而变化蓝桉。在这两个物种中，可溶性愈创木酚过氧化物酶 (GPRX) 活性从 Texc 增加到 Tform，而细胞壁结合的 GPRX 活性随着时间的推移而增加巨桉，超越蓝桉。黄酮类化合物含量随时间增加而增加巨桉并且高于蓝桉在 Tform. 主成分分析表明，物种和时间引起的差异造成了近 80% 的方差。总体而言，数据表明巨桉显示出更高的形成层活性和更严格的氧化还原条件调节蓝桉。这些特征可能会影响基于 ROS 的信号传导和插条的植物激素稳态，从而影响 AR 的发育。除了成为 AR 发育差异领域的参与者之外，本文确定的具体特征还可以成为早期克隆选择和 AR 调节的潜在工具，旨在改善这种森林作物的克隆繁殖。