AM真菌提高枸杞耐盐性的机制研究

发布时间：2018-08-15 13:54

【摘要】：本研究调查了宁夏盐土丛枝菌根(arbuscular mycorrhizas,AM)真菌的多样性,并探明了影响盐土中AM真菌群落变化的主要土壤因子,阐述了AM真菌群落、土壤因子及植物种类之间的关系。在此基础上,从盐胁迫条件下AM真菌对枸杞激素调节、光合系统、抗氧化和渗透调节、叶超微结构和叶营养成分的影响等方面,研究了接种AM真菌提高枸杞耐盐性的生理生化机制。评估了盐胁迫条件下接种AM真菌作为生物肥料,提高枸杞生长以及改善枸杞产品品质的潜力。主要研究结论如下:1.宁夏盐土AM真菌群落多样性在宁夏盐土枸杞(Lycium barbarum L.)和沙枣(Elaeagnus angustifolia L.)2种植物根际盐土中鉴定出33种AM真菌,隶属于7个科10个属。其中,球囊霉科(Glomeraceae)的AM真菌数目最多,包含13种,Acaulospora和Glomus在属水平上丰度最高,分别包含10种和9种,Septoglomus constrictum是丰度最高的种,2种植物共有种是S.constrictum和Funneliformis coronatum,表明宁夏盐土中具有很高的AM真菌群落多样性。枸杞与沙枣根际的AM真菌群落显著不同(R=0.26,p0.05),枸杞根际分离出27种AM真菌,远高于沙枣的12种,枸杞根际AM真菌群落的Shannon、Simpson和Evenness等指数也显著高于沙枣,表明宿主会影响AM真菌群落结构。2.土壤因子对宁夏盐土AM真菌群落多样性的影响盐胁迫程度与AM真菌多样性指数成显著负相关,表明盐胁迫会降低AM真菌多样性。但是,土壤肥力指标(速效钾、速效磷、速效氮和全磷)与AM真菌多样性成显著正相关,表明土壤肥力提升会增加AM真菌多样性。土壤pH与孢子丰度成正相关,表明偏碱性土壤有利于AM真菌产孢。速效磷与AM真菌均一度成正相关,说明土壤磷含量能提高AM真菌种间均衡度。由此可见,土壤因子能显著影响AM真菌群落结构。3.盐胁迫条件下AM真菌对枸杞激素调节及生长的影响在盐胁迫条件下,接种Glomus versiforme的枸杞叶和根部IAA含量分别提高59.0%和39.1%,叶ABA含量提高13.8%。协方差分析表明,G.versiforme直接影响了枸杞的IAA和ABA含量,并且通过参与这2种激素的调控,使枸杞的生物量提高1.75倍,根系总吸收和活跃吸收面积分别增加2.17和2.66倍。接种G.versiforme的枸杞株高、地径和单株叶片数等形态指标分别提高93.6%、57.8%和86.6%,表明接种G.versiforme的枸杞长势更好。由此可见,接种G.versiforme通过对枸杞激素调节,显著缓解了盐胁迫对枸杞生长的抑制作用,特别是促进了枸杞根系的生长发育,保证了枸杞对水分和养分的吸收功能。4.盐胁迫条件下AM真菌对枸杞光合系统的影响在盐胁迫条件下,研究了接种G.versiforme对枸杞叶绿素、光合作用和叶绿素荧光的影响。结果显示,G.versiforme在非盐胁迫下使枸杞的叶绿素含量提高25.7%。枸杞的叶绿素含量未受到盐胁迫的影响,说明枸杞具有较强的耐盐能力。在盐胁迫条件下枸杞的光合作用显著降低,叶绿素荧光也受到很大抑制。但是,接种G.versiforme的枸杞在100 mM盐浓度下,其光合速率和蒸腾速率分别比对照提高56.0%和28.7%,胞间CO2浓度降低9.0%。在200 mM盐浓度下,接种G.versiforme的枸杞的电子传递效率(ΦPSⅡ)、光化学猝灭系数(qP)及非光化学猝灭系数(qN)均显著高于对照,表明G.versiforme能提高枸杞的光能捕获能力,并协助其合理分配能量,以保证枸杞在盐胁迫下的光合作用以及叶的光合系统免受光氧化损伤。5.盐胁迫条件下AM真菌对枸杞抗氧化和渗透调节的影响本试验研究了盐胁迫下接种G.versiforme对枸杞抗氧化酶活性、渗透调节物质以及水势的作用。结果表明,接种AM真菌枸杞的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性分别提高11.0%和7.6%,过氧化氢酶(CAT)活性在100 mM盐胁迫下提高2.85倍,表明G.versiforme能提高枸杞的抗氧化酶活性,降低膜系统的损伤。同时,G.versiforme提高了枸杞的可溶性糖(32.3%)和还原糖(33.6%)含量,降低了淀粉含量(23.8%),表明G.versiforme能促进枸杞淀粉水解成可溶性糖和还原糖,进而提高枸杞的水势(32.6%)。以上结果表明,G.versiforme能在盐胁迫下提高枸杞抗氧化酶活性和渗透调节能力。6.盐胁迫条件下AM真菌对枸杞叶超微结构的影响本研究评估了接种G.versiforme对盐胁迫下枸杞叶细胞超微结构的影响。盐胁迫严重损伤了对照枸杞叶细胞膜结构,导致质壁分离并破坏了叶绿体类囊体和基质片层。与对照相比,接种G.versiforme的枸杞叶肉细胞质壁分离程度较轻,叶绿体相对完整且积累的油滴数较少,基粒和类囊体完好有序。这些结果表明,G.versiforme在盐胁迫下有效保护了枸杞叶细胞的结构。7.盐胁迫条件下接种AM真菌对枸杞叶营养成分的影响本研究在施加盐胁迫条件下接种Rhizophagus irregularis于菜用枸杞,测定R.irregularis对枸杞叶营养成分的影响。结果显示,R.irregularis在非胁迫与盐胁迫条件下,使枸杞芽的再生速率分别提高了79.0%和113.0%。与对照相比,在盐胁迫条件下,接种R.irregularis使2次收获的枸杞叶芦丁含量分别提高了96.1%和77.5%,枸杞叶酸性多糖分别增加了66.7%和103.1%。此外,R.irregularis还提高了2次收获枸杞叶的多糖含量,增加幅度分别为9.9%和32.5%。结果表明,R.irregularis在盐胁迫下能显著提高枸杞芽的再生速率,增加枸杞叶的营养成分。
[Abstract]:In this study, the diversity of arbuscular mycorrhizas (AM) fungi in Ningxia saline soil was investigated, and the main soil factors affecting the changes of AM Fungi Community in saline soil were identified. The relationships among AM fungi community, soil factors and plant species were expounded. Physiological and biochemical mechanisms of AM fungi inoculation on improving salt tolerance of Lycium barbarum were studied. The potential of AM fungi inoculation as biofertilizer to improve the growth and quality of Lycium barbarum under salt stress was evaluated. The main conclusions are as follows: 1. The diversity of AM Fungi Community in summer saline soil was identified in the rhizosphere saline soil of Lycium barbarum L. and Elaeagnus angustifolia L. in Ningxia. 33 species of AM fungi belonging to 10 genera and 7 families were identified. Among them, the number of AM fungi in Glomeraceae was the largest, including 13 species, Aclospora and Glomusau were the richest. Septoglomus constrictum was the highest abundant species, and S. constrictum and Funneliformis coronatum were the common species, indicating that there was a high diversity of AM fungal communities in Ningxia saline soil. The Shannon, Simpson and Evenness indices of AM Fungi Community in Lycium barbarum rhizosphere were also significantly higher than those in Elaeagnus angustifolia L. in 12 species of Elaeagnus angustifolia, suggesting that host could affect the structure of AM fungi community. 2. The effect of soil factors on the diversity of AM Fungi Community in Ningxia saline soil was negatively correlated with the diversity index of AM fungi, suggesting that salt Diversity. However, soil fertility indices (available potassium, available phosphorus, available nitrogen and total phosphorus) were positively correlated with AM fungi diversity, indicating that soil fertility increased AM fungi diversity. Soil pH was positively correlated with spore abundance, indicating that alkaline soil was conducive to AM fungi sporulation. The results showed that soil factors could significantly affect the structure of AM fungi community. 3. The effects of AM fungi on hormone regulation and growth of Lycium barbarum L. Under salt stress, IAA content in leaves and roots of Lycium barbarum inoculated with Glomus versiform increased by 59.0% and 39.1%, respectively, and ABA content in leaves increased by 13.8%. Covariance analysis showed that G. versiform directly affected the contents of IAA and ABA in Lycium barbarum. By participating in the regulation of these two hormones, the biomass of Lycium barbarum was increased by 1.75 times, the total absorption and active absorption area of root system were increased by 2.17 and 2.66 times, respectively. 3.6%, 57.8% and 86.6% showed that the growth of Lycium barbarum inoculated with G.versiform was better. Therefore, G.versiform significantly alleviated the inhibition of salt stress on the growth of Lycium barbarum, especially promoted the growth and development of Lycium barum roots, and ensured the absorption of water and nutrients of Lycium barum. 4. AM was true under salt stress. The effects of G. versiform on chlorophyll, photosynthesis and chlorophyll fluorescence of Lycium barbarum L. were studied under salt stress. The results showed that G. versiform increased the chlorophyll content of Lycium barbarum L. by 25.7% under non-salt stress. The chlorophyll content of Lycium barum L. was not affected by salt stress, indicating that Lycium barbarum L. had stronger chlorophyll content. The photosynthesis and chlorophyll fluorescence of Lycium barbarum L. were significantly decreased under salt stress. However, the photosynthetic rate and transpiration rate of Lycium barbarum L. inoculated with G. versiform at 100 mM increased by 56.0% and 28.7% respectively, and the intercellular CO2 concentration decreased by 9.0%. Electron transfer efficiency (PSII), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qN) of Lycium barbarum L. were significantly higher than those of the control, indicating that G. versiform could improve the photosynthetic capture ability of Lycium barbarum L. and help it distribute energy reasonably, so as to ensure the photosynthesis of Lycium barum L. under salt stress and protect the photosynthetic system from photooxidation damage.5. Effects of AM fungi on antioxidant and osmotic regulation of Lycium barbarum L. Under salt stress, the effects of G. versiform on the activities of antioxidant enzymes, osmotic regulators and water potential of Lycium barum L. were studied. The results showed that the activities of superoxide dismutase (SOD) and peroxidase (POD) of Lycium barum L. inoculated with AM fungi increased by 11.0% and 7.6% respectively. Catalase (CAT) activity increased by 2.85 times under 100 mM salt stress, indicating that G. versiform could increase the activity of antioxidant enzymes and reduce the damage of membrane system in Lycium barbarum. At the same time, G. versiform increased the content of soluble sugar (32.3%) and reducing sugar (33.6%) and decreased the content of starch (23.8%) in Lycium barbarum, suggesting that G. versiform could promote the hydrolysis of starch in Lycium barum barbarum. The above results showed that G. versiform could increase the activity of antioxidant enzymes and osmotic regulation of Lycium barbarum L. under salt stress. 6. The effect of AM fungi on ultrastructure of Lycium barbarum L. leaves under salt stress was evaluated in this study. The chloroplast thylakoids and stroma lamellae were separated and destroyed seriously by salt stress. Compared with the control, the isolation degree of mesophyll cytoplasmic wall of Lycium barbarum inoculated with G. versiform was lighter, the chloroplast was relatively intact and accumulated less oil droplets, and the matrix and thylakoids were intact and orderly. The results showed that G. versiform effectively protected the structure of Lycium barbarum leaf cells under salt stress. 7. Effects of AM fungi inoculation on the nutritional components of Lycium barbarum leaves under salt stress. Rhizophagus irregularis was inoculated in Lycium barbarum under salt stress. The effects of R. irregularis on the nutritional components of Lycium barbarum leaves were determined. Irregularis increased the regeneration rate of Lycium barbarum buds by 79.0% and 113.0% under non-stress and salt stress, respectively. Compared with the control, inoculation with R. irregularis increased the rutin content of Lycium barbarum leaves by 96.1% and 77.5%, and the acid polysaccharide content of Lycium barum leaves by 66.7% and 103.1% respectively under salt stress. The results showed that R. irregularis could significantly increase the regeneration rate of Lycium barbarum buds and the nutritional components of Lycium barbarum leaves under salt stress.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S567.19

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