In their evolution, grasses have developed symbiotic associations with fungi including mycorrhizal fungi that grow in or on the roots, and endophytes that live their entire life cycle within the aerial portion of the host grass, typically forming nonpathogenic, systemic and usually intercellular associations. Currently, seven genera have been identified, including Atkinsonella, Balansia, Balansiopsis, Echinodothis, Epichloё , Myriogenospora and Parepichloё. Among them, the anamorphic (imperfect) stage of Epichloё spp., i.e. Neotyphodium spp., is most closely related to cultivated grasses. The most widely known Neotyphodium endophytes are N. lolii and N. coenophialum, which colonize perennial ryegrass ( Lolium perenne L.) and tall fescue ( Festuca arundinaceae Schreb .) respectively. Endophytes may protect the hosts from biotic and abiotic stresses. In the past twenty years, much research has focused on the beneficial effect of endophyte infection on the biotic stress resistance of host grasses such as mammalian, insect and nematode herbivores. When abiotic stress was regarded, many studies showed that endophyte infection could improve drought resistance ability of host grasses. Similar to drought stress, salt stress also led plants to physiological drought. But up to now, no related research results were reported. Thus, in this paper Lolium perenne cv SR4000 infected by Neotyphodium lolii was chosen as experimental material. Vegetative growth and several physiological indexes (such as free proline content, soluble sugar content and photochemical efficiency of PSII) of endophyte-infected (EI) and endophyte-free (EF) populations under normal and salt stress conditions were compared in order to discuss the effect of endophyte infection on the salt resistant ability of the host ryegrass. The experiment was performed under greenhouse condition. EI and EF plants were transplanted into culture pots filled with 1L 1/2 Hoagland solution. One week later, salt (NaCl) was added to impose salt stress (control, low and high stress). Salt content for the above stresses was 0, 0.3% and 0.6%, respectively. Each treatment was replicated 5 times. From the beginning, tiller number and free proline content of each population were recorded every 5 days. Photochemical efficiency of PSII of experimental populations was surveyed at the middle and late period separately. At the end of the experiment, shoots and roots were harvested and weighed separately. At the same time, soluble sugar content of both shoots and roots was measured. The whole experiment lasted 35 days. During the period, distilled water was supplied whenever the solution level in the pot dropped due to transpiration and evaporation. The results showed that endophyte infection did not improve shoot growth of ryegrass. Under high salt stress, tillering ability and shoot biomass of EI populations were all lower than those of EF populations. However, endophyte infection was beneficial to roots of ryegrass, which was demonstrated by the fact that root biomass of EI populations, under salt stresses, decreased more slowly than that of EF populations. When it came to the ratio of root to shoot, no significant change was observed between under control and under high salt stress for EI populations, while for EF populations, it decreased significantly in comparison with control, and the decrease rate was up to 41.7%. Taking these factors in consideration, under high salt stress, EI populations may maintain root growth at the cost of shoot growth, which may be beneficial to their survival. Salt stresses led to increase of free proline content of ryegrass leaves, and the degree of increase was heightened with extended stress time and advanced stress level. When compared with EF populations, proline content of EI populations was higher and especially significant under high stress. As for the content of soluble sugar, its value was similar under both control and low salt stress in EI and EF populations. Under high salt stress, however, the sugar content of EI populations was significantly lower than that of EF populations, which was considered to be unbeneficial to host grass’ survival. Moreover, during the experimental period, photochemical efficiency of PSⅡ was measured three times, but no significant difference was observed between EI and EF populations. In conclusion, endophyte infection did not alleviate negative effect of salt stress on the host ryegrass.

以感染内生真菌的多年生黑麦草（ Lolium perenne  L.） (SR4000)为实验材料，建植内生真菌感染（EI）和不感染（EF）的黑麦草种群，并对其进行盐胁迫实验，通过观察生长和生理生态指标的变化，分析内生真菌对宿主植物抗盐性的影响。结果表明，内生真菌感染对宿主黑麦草的营养生长没有增益效应，相反在高盐浓度下，EI种群的分蘖能力和地上部分生物量均低于EF 种群；但内生真菌能够改变宿主种群生物量的分配格局，将更大比例的生物量分配于根系。在高盐浓度下，内生真菌感染可导致黑麦草叶内的脯氨酸含量显著增加、可溶性糖含量显著降低，但对PSⅡ光化学效率 F v /F m 值的变化没有影响。总体来看，内生真菌感染并未改善宿主黑麦草的抗盐性。

Seed germination and seedling growth of Neotyphodium endophytE-infected(E+)and endophytE-free(E-)wild barley( Hordeum brevisubulatum )were observed under temperature and simulated drought stress conditions.Results show that germination rate and germination index of E+ seed were significantly higher than those of E-seeds( P P Neotyphodium endophyte can improve the germination rate,germination speed,seedling growth,capacity of water self-absorption of wild barley under lower and higher temperature and water stress conditions.

本文通过比较携带(E+)和未携带(E-)内生真菌( Neotyphodium )的野大麦种子( Hordeum brevisubulatum )在温度胁迫和模拟干旱胁迫条件下种子的发芽速度、发芽率、根苗长以及幼苗含水量等方面的差异,探讨了内生真菌在对宿主植物抗逆境胁迫条件下的增益作用。结果表明:在10℃,15℃低温胁迫和30℃高温胁迫时,E+种子的发芽率、发芽指数显著大于E-种子( P P P <0.05),表明内生真菌可以促进宿主植物在温度和干旱胁迫环境中发芽后幼苗的生长,并增强植株自主吸收水分的能力。

The effects of the volatile oils from drunken horse grass infected (E+) and noninfected (E-) by Neotyphodium gansuense on germination and antioxidative enzyme activity involving superoxide dismutase (SOD) and peroxidase (POD) of perennial ryegrass (Lolium perenne) were determined. The germination experiment showed that the seed germination and POD activities of the perennial ryegrass under E- treatment were significantly (P

以内生真菌侵染(E+)和未侵染的(E-)醉马草(Achnatherum inebrians)植株中提取的挥发油为材料，通过纸上芽床试验，研究其对多年生黑麦草(Lolium perenne)种子萌发和幼苗生长的影响。结果发现，醉马草挥发油对黑麦草种子萌发具有抑制作用，且受到的抑制作用随挥发油浓度的增加而增大。E+挥发油的抑制作用强于E-，当挥发油浓度达到300 mg·mL-1时，黑麦草的发芽率、胚芽长、胚根长、鲜重和干重等均表现出显著差异(P

The outside pot experiment was performed and the growth and physiological characteristics of Neotyphodium endophyte-infected(E+) and endophyte-free(E-) wild barley( Hordeum brevisubulatum (Trin.) Link) were observed under different NaCl concentrations(0,100,200,and 300 mmol L -1 ).The results show that the tiller number,biomass accumulation,contents of soluble sugar and proline,and activity of SOD isozyme of E+ plants were significantly higher( P P <0.05),than those of E-plants.In conclusion,endophyte infection improved the salt tolerance of wild barley under outside pot conditions.

在室外盆栽条件下,通过比较带内生真菌(E+)与不带内生真菌(E-)的野大麦( Hordeum brevisubulatum (Trin.)Link)在不同NaCl浓度(0、100、200、300 mmolL -1 )条件下的生长与生理指标变化,分析了内生真菌对宿主野大麦耐盐性的影响。结果表明:在高盐浓度(300 mmol L -1 )下内生真菌显著提高了宿主野大麦分蘖能力、生物量积累、可溶性糖含量、脯氨酸含量、SOD酶活性( P <0.05),同时降低了丙二醛含量,说明内生真菌的侵入有利于提高宿主野大麦在室外盆栽条件下的耐盐性。

The changes of physiological and biochemical resistance indices(RWC,RPP,Pro,Chl,SOD,CAT,and MDA) of six Lolium perenne L.varieties were studied under PEG stress and their drought resistances were comprehensively assessed.The results show that the leaves of cultivars with the stronger drought resistance had more water retention quantities,higher chlorophyll contents,more accumulation of proline contents,and relatively low membrane permeability.Based on the comprehensive evaluation of physiological and biochemical characters,the drought resistance of six cultivars decreased in the following order as Accent,Premier,Bartwingo,Pinnacle,Cutter,and Fairway.

研究6个多年生黑麦草( lolium perenne L.)品种在模拟干旱条件下相对含水量、细胞膜相对透性、游离脯氨酸、叶绿素、超氧化物歧化酶、过氧化氢酶及丙二醛含量等抗性生理生化指标的变化,并对其抗旱性进行综合评价。结果表明,抗旱性强的品种在干旱胁迫(PEG胁迫)下叶片保水力强,叶绿素含量高,游离脯氨酸维持积累时间长且累积量较高,并能保持相对较高的细胞膜完整性。经抗旱性综合评价得出,6个品种抗旱性强弱依次为:爱神特>首相>百舸>顶峰>卡特>球道。

Neotyphodium endophytes are a group of clavicipitaceous fungi that form symbiotic associations with a broad spectrum of grasses within the Pooideae family. The major benefits for grass endophytes are access to nutrients from the apoplast and a means of dissemination through the seed. Benefits to the host include protection from mammalian and insect herbivory, resistance to nematodes and some fungal pathogens, drought tolerance and greater field persistence. Since Read & Camp first reported the close relatio...

以内生真菌感染 (endophyte- infected,EI)与不感染 (endophyte- free,EF)的黑麦草 (L olium perenne L.)种子建立实验种群 ,分别对其施加长时间不同强度的干旱胁迫 ,通过比较黑麦草体内过氧化物酶 (POD)、超氧化物歧化酶 (SOD)、多酚氧化酶(PPO)活性及其同工酶谱的变化以探讨保护酶系统在内生真菌——植物共生体的抗旱性方面所作的贡献。研究结果表明 ,水分胁迫和内生真菌对黑麦草 3种酶的影响不仅表现在总量上而且表现在同工酶的酶谱及各区带的酶活力上。就总酶活力而言 ,EI和 EF植株中 POD、SOD和 PPO的活性均随着干旱胁迫强度的增加而增加 ,进一步将 EI和 EF植株的酶活力进行比较 ,发现与 EF植株相比 ,EI植株中 POD和 PPO的活性相对较低 ,而 SOD的活性相对较高。从同工酶的谱带数量和强弱来看 ,POD同工酶各区带活力均随干旱胁迫强度的增加而增加 ,EI植株叶片增加的幅度高于 EF叶片 ,而且 EI叶片在重度胁迫下出现了 1条新带 ;SOD同工酶各区带活力在 EI叶片中有随干旱胁迫增加而增加的趋势 ,而在 EF叶片中有些区带酶活力增强，有些区带酶活力减弱，且EI叶片在中度胁迫下出现了1条新带；PPO同工酶随干旱胁迫的增强，EI和EF叶片均表现为有些区带酶活力增强，有些区带酶活力减弱。总之，内生真菌的感染虽然没有显著提高宿主植物黑麦草POD、SOD和PPO的活性，但使宿主黑麦草对干旱胁迫的反应更为迅速，其中既包括POD、SOD等酶活力的迅速升高，也包括新酶带的产生。