Qiu Daiyu, Wang Xue, Xu Fengbin, Li Qian, Ren Fengying, Jiang Kan
College of Agronomy, Gansu Agricultural University, Lanzhou, China.
Gansu Key Laboratory of Arid Habitat Crop Science, Lanzhou, China.
PLoS One. 2025 Jan 31;20(1):e0315657. doi: 10.1371/journal.pone.0315657. eCollection 2025.
Water-soluble constituents in the root exudates of C. pilosula exhibit both allelopathic and auto-toxic properties, which substantially impede its growth. To mitigate the constraints associated with the continuous cropping of C. pilosula, this study examined the impact of aqueous extracts from the root exudates at various developmental stages on seed germination and seedling growth. Additionally, we isolated and characterized significant auto-toxic allelochemicals. Our findings revealed that the inhibitory effects on seed germination, seedling growth, and the activity of antioxidant enzymes-collectively referred to as a comprehensive effect-intensified progressively with increasing concentrations of the aqueous extracts from C. pilosula root exudates. The most pronounced auto-toxic comprehensive effect was observed with extracts at a concentration of 50 mL during the reproductive phase, diminishing SOD and POD activities, and MDA levels in C. pilosula seedlings by 72.3%, 71.7%, and 83.3% respectively, compared to the control (P<0.05). Three primary allelopathic compounds-acetic acid, hexamethyl cyclotrisiloxane, and methoxybenzene oxime were isolated and identified in the aqueous extracts. Acetic acid, constituting 44.1% of the total chemical profile, exhibited a significant inhibitory effect on seed germination and seedling growth (P<0.05). In conclusion, the aqueous extracts of C. pilosula root exudates significantly inhibit seed germination and seedling growth, especially during the plant's reproductive stage, with low molecular weight organic acids being the predominant allelopathic components.
党参根系分泌物中的水溶性成分具有化感和自毒特性，这严重阻碍了其生长。为减轻与党参连作相关的限制，本研究考察了党参根系分泌物在不同发育阶段的水提取物对种子萌发和幼苗生长的影响。此外，我们还分离并鉴定了重要的自毒化感物质。我们的研究结果表明，对党参根系分泌物水提取物浓度的增加，其对种子萌发、幼苗生长和抗氧化酶活性的抑制作用（统称为综合效应）会逐渐增强。在生殖阶段，浓度为50 mL的提取物观察到最明显的自毒综合效应，与对照相比，党参幼苗的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性以及丙二醛（MDA）水平分别降低了72.3%、71.7%和83.3%（P<0.05）。从水提取物中分离并鉴定出三种主要化感化合物——乙酸、六甲基环三硅氧烷和甲氧苯肟。乙酸占化学组成总量的44.1%，对种子萌发和幼苗生长表现出显著抑制作用（P<0.05）。总之，党参根系分泌物水提取物显著抑制种子萌发和幼苗生长，尤其是在植物生殖阶段，低分子量有机酸是主要的化感成分。
