马铃薯根系分泌物对肉桂酸胁迫下穿心莲幼苗的化感效应研究

Allelopathic effects of potato root exudates on Andrographis paniculata seedings under cinnamic acid stress

关键词:  穿心莲, 马铃薯根系分泌物, 化感作用, 根边缘细胞, 肉桂酸(CA), 轮作

Key words:  Andrographis paniculata, potato root exudates, allelopathic effects, root border cells, cinnamic acid(CA), crop rotation

摘要:

为探明马铃薯-穿心莲轮作系统中马铃薯根系分泌物对酚酸类化感物质的影响机制,验证马铃薯-穿心莲轮作模式的可行性,该研究以穿心莲种子为材料,探究马铃薯根系分泌物对肉桂酸胁迫下穿心莲种子萌发、根边缘细胞形态和根尖抗氧化酶活性的影响。结果表明:(1)在0.4 mmol·L^-1肉桂酸胁迫下,添加不同浓度的马铃薯根系分泌物,均能促进穿心莲种子各萌发指标化感效应指数的提升,分泌物浓度为25 mg·mL^-1的促进效果最佳。(2)相较于肉桂酸(CA)处理,添加马铃薯根系分泌物显著提高了穿心莲根边缘细胞的数量和活率,降低了凋亡率和黏胶层厚度(P<0.05)。(3)马铃薯根系分泌物处理后,穿心莲根尖超氧化物歧化酶、过氧化物酶、过氧化氢酶的活性和丙二醛含量均显著下降,根系活力显著上升(P<0.05)。综上表明,马铃薯根系分泌物可通过减轻穿心莲根边缘细胞的化感胁迫、降低幼苗根尖氧化损伤程度的方式,提高穿心莲萌发与幼苗时期对肉桂酸的耐受能力,缓解肉桂酸对穿心莲幼苗生长的化感抑制作用。该研究结果为马铃薯-穿心莲轮作模式的合理性提供了理论依据。

Abstract:

In order to confirm the viability of the potato-Andrographis paniculata rotation mode, and to investigate the effect mechanism of potato root exudates on phenolic acid allelochemicals in the potato-A. paniculata rotation system, the seeds of A. paniculata were used as materials to explore the effects of potato root exudates on seed germination, root border cell morphology, and root tip antioxidant enzyme activity of A. paniculata under cinnamic acid stress. The results were as follows:(1)0.4 mmol·L^-1 cinnamic acid significantly inhibited the germination and growth of A. paniculata seeds. Adding different concentrations of potato root exudates had a certain mitigation effect on all gerimation indexes. When the concentration of root exudate was 25 mg·mL^-1, the allelopathic effect index of each index reached its maximum value, indicating that the mitigation effect was the strongest at this time. Each germination index showed significant differences compared to the cinnamic acid group(P<0.05).(2)Cinnamic acid strongly damaged the root border cells of A. paniculata seedlings and significantly reduced the number and viability of root border cells. Adding potato root exudates could effectively alleviate this damage. After root exudates treatment, the number and viability of cells at the root border of A. paniculata increased significantly, and the apoptosis rate and thickness of the mucilage layer decreased significantly(P<0.05).(3)Cinnamic acid caused strong stress damage to the root tip of A. paniculata, which led to an imbalance of the antioxidant enzyme system and decreased root activity. After the treatment of potato root exudates, the activities of superoxide dismutase, peroxidase, catalase, and malondialdehyde content in the root tip of A. paniculata decreased significantly, and the root activity increased significantly(P<0.05), indicating that the degree of damage to the root tip decreased. In conclusion, potato root exudates can reduce the degree of oxidative damage to the root tip of seedlings by reducing the allelopathic stress of root marginal cells, improve the tolerance of A. paniculata to cinnamic acid during germination and the seedling stage, and alleviate the allelopathic inhibition of cinnamic acid on the growth characteristics of A. paniculata seedlings. The results provide a theoretical reference for the rationality of the potato-A. paniculata rotation mode.