摘 要

深色有隔内生真菌（Dark septate endophytes, DSE）是近年来受到广泛关注的一类植物共生真菌，宿主非常广泛，几乎遍布于地球上各种生境中。国内外研究表明，DSE根内共生能提高宿主植物的生物量，促进宿主植物对营养元素的吸收，提高宿主植物的抗病性和抗逆性。然而，宿主植物的种类、所处的生境均会对DSE与植物的共生关系产生影响，DSE与宿主植物的互作关系还没有一致的结论。另外，国内外对DSE的研究几乎都是在陆生环境下开展的，尽管DSE对湿地环境也有一定的适应性但其在湿地生境中发挥的生态学功能尚不明确，需要进一步探索。因此，为了明确接种DSE对湿地植物的接种作用，本文以芦苇为实验材料，以沙门外瓶柄霉为实验菌种，通过盆栽实验在水淹、正常、干旱条件下研究DSE对芦苇生长、渗透调节物质、抗氧化酶活性和叶绿素含量等的影响。研究结果如下：

在水淹条件下，DSE能明显促进湿地植物的生长。此条件下，DSE的侵染率为30%，接种DSE能显著提高芦苇的生物量（20.68%），地径也所有增加（14.29%）。接菌芦苇幼苗体内可溶性糖明显降低了（36.45% ），脯氨酸含量大幅降低（66.21%），丙二醛（MDA）含量大幅下降（53.73%）。芦苇幼苗叶绿素含量有较大提高（34.19%），表明接种DSE在促进芦苇生长和光合色素积累方面发挥重要作用，也能通过渗透调节作用降低水淹环境对植物的伤害。

在水分正常条件下，接种DSE对芦苇幼苗的侵染率为32.5%，生物量减少21.78%，表明接种DSE对湿地植物的生长是不利的。而接菌芦苇幼苗可溶性糖含量增加（19.11%），可溶性蛋白含量增加（9.57%），脯氨酸含量大幅降低（70.18%），超氧物歧化酶（SOD）活性提高（27.68%），过氧化氢酶（CAT）活性提高（18.42%），叶绿素含量小幅降低（8.57%）。因此，在正常水分条件下，DSE接种并没有对植物生长和光合作用产生积极的影响，但接种后提高了芦苇的渗透调节能力和抗氧化能力，芦苇的抗逆性有所提升。

在干旱胁迫条件下，接种DSE对芦苇幼苗的侵染率为45%，生物量减少（13.75%），说明接种DSE对湿地植物的生长是不利的。可溶性糖降低（17.72%），可溶性蛋白明显增加（48.78%），SOD酶活性降低显著降低（73.68%），CAT酶活性提高（10.26%），MDA有明显提高（40.31%）。叶绿素含量降低（22.22%）。因此，干旱条件下，DSE侵染活性增强，但降低了植物的渗透调节作用和抗氧化作用，光合作用减弱。

三种水分条件下，DSE对芦苇产生了不同的接种效应。水淹条件下，DSE促进芦苇生长，增强芦苇光合作用，并能通过渗透调节作用和抗氧化作用降低水分胁迫对芦苇的伤害；正常水分条件下，DSE不利于芦苇生长和光合作用，但能够提高芦苇的抗逆能力；干旱条件下，DSE接种对芦苇生长产生抑制作用，并对芦苇的生理抗性产生消极影响。

关键词：深色有隔内生真菌；芦苇；水分胁迫；渗透调节物质；抗氧化酶活性；

Abstact

Dark septate endophytes (DSE) are a type of plant symbiotic fungi that have received widespread attention in recent years. The hosts are very widespread and are found in almost all habitats on Earth. Studies at home and abroad show that DSE root symbiosis can increase the biomass of host plants, promote the absorption of nutrient elements by host plants, and improve the disease resistance and stress resistance of host plants. However, the type of host plant and the habitat in which it is located will have an impact on the symbiotic relationship between DSE and plants. There is no consistent conclusion on the interaction between DSE and host plants. In addition, research on DSE at home and abroad is almost always carried out in the terrestrial environment. Although DSE also has certain adaptability to the wetland environment, the ecological functions it plays in the wetland habitat are not yet clear and needs further exploration. Therefore, in order to confirm the inoculation of wetland plants with DSE, in this paper, the growth and infiltration of DSE on reeds were studied under the condition of flooding, normal and drought under the conditions of flooding, normal and drought by taking reed as experimental material and S. exigua as experimental bacteria. Regulates the effects of substances, antioxidant enzyme activity, and chlorophyll content. The results of the study are as follows:

Under flooded conditions, DSE can significantly promote the growth of wetland plants. Under this condition, the infection rate of DSE was 30%. Inoculation with DSE significantly increased the biomass of reed (20.68%), and the ground diameter also increased (14.29%). The soluble sugar in the seedling reed seedlings significantly decreased (36.45%), the proline content decreased significantly (66.21%), and the malondialdehyde (MDA) content decreased significantly (53.73%). The chlorophyll content of reed seedlings increased greatly (34.19%), indicating that inoculation with DSE plays an important role in promoting the growth of reeds and photosynthetic pigment accumulation, and can also reduce the damage of flooded environment to plants through osmotic adjustment.

Under normal water conditions, the inoculation rate of DSE on reed seedlings was 32.5% and the biomass decreased by 21.78%, indicating that inoculation with DSE was unfavorable to the growth of wetland plants. The soluble sugar content of the seedling reed seedlings increased (19.11%), the soluble protein content increased (9.57%), the proline content decreased significantly (70.18%), and the superoxide dismutase (SOD) activity increased (27.68%). The activity of oxidase (CAT) increased (18.42%) and the chlorophyll content decreased slightly (8.57%). Therefore, under normal water conditions, DSE inoculation did not have a positive effect on plant growth and photosynthesis, but after inoculation, the osmotic adjustment ability and antioxidant capacity of the reed were improved, and the resilience of the reed was improved.

Under drought stress, the inoculation rate of DSE on reed seedlings was 45% and the biomass decreased (13.75%), indicating that inoculation with DSE was unfavorable to the growth of wetland plants. Soluble sugars decreased (17.72%), soluble protein increased significantly (48.78%), SOD enzyme activity decreased significantly (73.68%), CAT enzyme activity increased (10.26%), and MDA increased significantly (40.31%). Chlorophyll content decreased (22.22%). Therefore, under drought conditions, DSE infection activity is enhanced, but the plant's osmotic adjustment and anti-oxidation effects are reduced, and photosynthesis is weakened.

DSE produced different inoculation effects on reeds under three water conditions. Under flooded conditions, DSE promotes the growth of reeds, enhances the photosynthesis of reeds, and reduces the damage of reeds caused by water stress through osmoregulation and antioxidation. Under normal water conditions, DSE is not conducive to growth and photosynthesis of reeds, but can be increased. The resilience of reeds; Under drought conditions, DSE inoculation inhibits the growth of reeds and negatively affects the physiological resistance of reeds.

Keywords: Dark septate endophytes; Phragmites communis ; Water stress; Osmotic adjustment substances; Antioxidant enzyme activity;