丛枝菌根真菌与深色有隔内生真菌对姜瘟病的防效及抗病机理初探

Preventive effects of arbuscular mycorrhizal fungi and dark septate endophytes on ginger and the anti-disease mechanism

摘要:

【背景】青枯劳尔氏菌(Ralstonia solanacearum, R.S)引发的姜瘟病是生姜产业发展的瓶颈问题。丛枝菌根真菌(arbuscular mycorrhiza fungi, AMF)与深色有隔内生真菌(dark septate endophytes, DSE)是两类重要的共生微生物。【目的】前期研究发现，AMF与DSE可提高生姜对姜瘟病的抗性，但其抗病机制尚不清楚，极大地限制了利用这两类共生真菌对该病的防治。【方法】在温室条件下做盆栽试验，以生姜组培苗为材料，设立接种AMF、DSE和不接种AMF、DSE的对照(CK)处理，并在上述处理下的植物生长4周后淋入病原菌液，病原菌接种1周后，通过测定菌根侵染率、发病率、叶绿素含量、光合指标、磷(P)含量、防御性酶活性及丙二醛(malondialdehyde, MDA)含量，研究AMF和DSE互作对病原菌侵染后生姜生长和生理生化指标的影响。【结果】AMF和DSE分别使姜瘟病发病率降低了45.27%和52.04% (p<0.05)。AMF+DSE组合处理抑病效果更好，发病率较对照降低60.87% (p<0.05)。AMF、DSE及二者共同作用的防效分别为62.54%、59.02%和68.50%。植物防御性酶活性表明，AMF显著提高了生姜超氧化物歧化酶(superoxide dismutase, SOD)、过氧化物酶(peroxidase, POD)、过氧化氢酶(catalase, CAT)和多酚氧化酶(polyphenol oxidase, PPO)活性，分别提高10.87%、1.15%、13.26%和0.14%；DSE显著提高SOD、POD、CAT和PPO活性，分别提高9.85%、17.47%、3.64%和0.67%；AMF与DSE互作显著提高SOD、POD、CAT和PPO活性，分别提高15.76%、18.19%、18.11%和14.93% (p<0.05)；MDA含量在AMF、DSE和二者互作条件下分别显著降低了3.38%、9.31%和25.79% (p<0.05)。【结论】AMF和DSE对姜瘟病有较好的防效，不仅能提高生姜幼苗的抗病能力，还能促进其生长，且二者共存时效果最好。

Abstract:

[Background] Ginger wilt caused by Ralstonia solanacearum (R.S) is a bottleneck in the development of the ginger industry. Arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are two kinds of important symbiotic microorganisms. [Objective] To explore the mechanism of AMF and DSE against ginger wilt. The previous study found that AMF and DSE could improve the resistance of ginger wilt, however, the synergic functioning mechanism was unclear, which limited the application of the two kinds of fungi to control the disease. [Methods] The pot experiments were carried out at room temperature with ginger-cultured seedlings as the material. The control (CK) treatment inoculated with AMF and DSE and without AMF and DSE were set up. After 4 weeks of growth under the above treatment, the plants were eluted with pathogen solution. One week after pathogen inoculation, the effects of AMF and DSE on the ginger growth and physiological and biochemical indexes infected with the pathogen were studied by determining the mycorrhizal infection rate, incidence, chlorophyll content, photosynthetic index, phosphorus (P) content, defensive enzyme activity, and malondialdehyde (MDA) content. [Results] AMF and DSE reduced the incidence of ginger wilt in ginger by 45.27% and 52.04%, respectively (P<0.05). AMF+DSE had a better effect on the prevention and control of this disease, and the incidence was reduced by 60.87% as compared with the control (P<0.05). The preventive effects of AMF, DSE, and AMF+DSE were 62.54%, 59.02%, and 68.50%, respectively. The activity of plant defensive enzymes indicated that AMF significantly increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO) by 10.87%, 1.15%, 13.26%, and 0.14%, respectively. DSE significantly increased the activities of SOD, POD, CAT, and PPO by 9.85%, 17.47%, 3.64%, and 0.67%, respectively. AMF+DSE significantly increased the activities of SOD, POD, CAT, and PPO by 15.76%, 18.19%, 18.11%, and 14.93%, respectively (P<0.05). AMF, DSE, and AMF+DSE significantly decreased the content of MDA by 3.38%, 9.31%, and 25.79%, respectively (P<0.05). [Conclusion] AMF and DSE have preventive effects on ginger wilt, which improve the disease resistance of ginger seedlings and promotes their growth, and the combination of AMF and DSE manifests the optimal effect.