Morales Orellana Raul Javier, Rath Thomas, Druege Uwe, Tandrón Moya Yudelsy A, von Wirén Nicolaus, Winkelmann Traud
Hochschule Osnabrück - University of Applied Sciences, Biosystem Engineering Laboratory (BLab), Osnabrück, Germany.
Leibniz University Hannover, Institute of Horticultural Production Systems, Section Woody Plant and Propagation Physiology, Hannover, Germany.
Front Plant Sci. 2024 Dec 16;15:1515990. doi: 10.3389/fpls.2024.1515990. eCollection 2024.
The presence of wounds in addition to the excision-induced wounds after severance from the stock plants is known to positively influence adventitious root formation of woody plant cuttings. Previous morphological studies highlighted laser wounding as a technique allowing to precisely control the decisive ablation depth. However, the biochemical processes involved in the response of rooting to the additional wounding remained unexplored.
The present study analyzed changes in the plant hormone and carbohydrate profiles in response to laser treatments of rose leafy single-node stem cuttings ( 'Pfänder'). Concentrations of four groups of plant hormones and of carbohydrates were monitored in three different stem sections of the cutting base during the first eight days after excision of cuttings. In addition, histology was employed to investigate anatomical changes at the basal wound and the laser wounds at the start and the end of the experiment after 40 days.
Laser ablation caused an increase of vascular tissue dimension directly in the laser wound, and increased the quantity and quality of rooting compared to control cuttings. A clear early local rise of jasmonic acid (JA) was detected directly in wounded areas after laser marking, as well as an increase in abscisic acid (ABA) that persisted for the subsequent days. Indole-3-acetic acid (IAA) levels were relatively high on day zero, but decreased thereafter. Interestingly, higher IAA levels were maintained in the stem section below the axillary bud compared with the opposite section. Laser-treated cuttings presented a clear increase in contents of IAA-amino acid conjugates (IAAGlu and IAAsp) and the oxidation product OxIAA. Differences in concentration of these IAA metabolites were related to the position of the laser wound relative to the axillary bud and leaf. Additionally, laser treatments caused gradually increased levels of the cytokinin N6-isopentenyladenine (iP) in laser-treated zones, and of zeatin riboside specifically when the laser wound was placed on the leaf-bud side. Additional laser wounding reduced starch and sucrose levels in all wounded sections at the end of the evaluation period, independently of the wounding location.
The results of this study indicate that presence of additional injured tissue triggers a complex biochemical adjustment at the base of the cutting responsible of inducing vascular tissue growth and capable of generating a positive response to adventitious root formation.
除了从母株上分离后切除诱导产生的伤口外，伤口的存在已知会对木本植物插条的不定根形成产生积极影响。先前的形态学研究强调激光创伤是一种能够精确控制决定性消融深度的技术。然而，生根对额外创伤反应中涉及的生化过程仍未得到探索。
本研究分析了玫瑰带叶单节茎插条（“Pfänder”）经激光处理后植物激素和碳水化合物谱的变化。在插条切除后的前八天，监测了插条基部三个不同茎段中四类植物激素和碳水化合物的浓度。此外，在实验开始和40天后结束时，采用组织学方法研究基部伤口和激光伤口处的解剖学变化。
激光消融直接导致激光伤口处维管组织尺寸增加，与对照插条相比，生根数量和质量均有所提高。激光标记后，在受伤区域直接检测到茉莉酸（JA）明显早期局部升高，以及脱落酸（ABA）在随后几天持续增加。吲哚 - 3 - 乙酸（IAA）水平在第零天相对较高，但此后下降。有趣的是，与相对的茎段相比，腋芽下方茎段中的IAA水平维持较高。激光处理的插条中IAA - 氨基酸共轭物（IAAGlu和IAAsp）和氧化产物OxIAA的含量明显增加。这些IAA代谢物浓度的差异与激光伤口相对于腋芽和叶片的位置有关。此外，激光处理导致激光处理区域中细胞分裂素N6 - 异戊烯基腺嘌呤（iP）水平逐渐升高，当激光伤口位于叶芽侧时，玉米素核苷水平尤其升高。在评估期结束时，额外的激光创伤降低了所有受伤茎段中的淀粉和蔗糖水平，与创伤位置无关。
本研究结果表明，额外受伤组织的存在会在插条基部引发复杂的生化调节反应，这种调节负责诱导维管组织生长，并能够对不定根形成产生积极反应。
