Arbuscular mycorrhizal fungi improve the growth and drought tolerance of Zenia insignis seedlings under drought stress

New Forests - Drought is one of the most critical limiting environmental factors for plant survival and restoration in areas of rocky desertification in southwestern China. Here, we aimed to...     

Effects of arbuscular mycorrhizal fungi on leaf solutes and root absorption areas of trifoliate orange seedlings under water stress conditions

The effects of the arbuscular mycorrhizal (AM) fungus Glomus mosseae on plant growth, leaf solutes and root absorption area of trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings were studied in potted culture under water stress conditions. Inoculation with G. mosseae increased plant height, stem diameter, leaf area, shoot dry weight, root dry weight and plant dry weight, when the soil water content was 20%, 16% and 12%. AM inoculation also promoted the active and total absorption area of root system and absorption of phosphorus from the rhizosphere, enhanced the content of soluble sugar in leaves and roots, and reduced proline content in leaves. AM seedings had higher plant water use efficiency and higher drought tolerance than non-AM seedlings. Effects of G. mosseae inoculation on trifoliate orange seedlings under 20% and 16% soil water content were more significant than under 12% soil water content. AM infection was severely restrained by 12% soil water content. Thus, effects of AM fungi on plants were probably positively related to the extent of root colonization by AM fungi. The mechanism of AM fungi in enhancing drought resistance of host plants ascribed to greater osmotic adjustment and greater absorption area of root system by AM colonization. __________ Translated from Journal of Plant Physiology and Molecular Biology, 2005, 30(5): 583–588 [译自: 植物生理与分子生物学报, 2005, 30(5): 583–588]     

Growth response of Pterocarpus santalinus seedlings to native microbial symbionts(arbuscular mycorrhizal fungi and Rhizobium aegyptiacum ) under nursery conditions

The objective of this research was to improve the growth and biomass of Pterocarpus santalinus L.f.(an endangered leguminous tree) using native microbial symbionts such as arbuscular mycorrhizal fungi and Rhizobium associated with native populations of P.santalinus.The native arbuscular mycorrhizal fungi isolated from P.santalinus soils were identified as(1) Glomus fasciculatum;(2)Glomus geosporum;and Glomus aggregatum.A nitrogenfixing microbial symbiont was isolated from the root nodules of P.santalinus and identified as Rhizobium aegyptiacum by16 s rRNA gene sequencing.These microbial symbionts were inoculated individually and in combination into P.santalinus seedling roots.After 90 days,growth and biomass had improved compared with uninoculated controls.Shoot and root lengths,number of leaves,stem circumference,number of root nodules,biomass,nutrient uptake and seedling quality index were significantly increased by a combined inoculation of arbuscular mycorrhizal fungi+Rhizobium aegyptiacum.It was concluded that native microbial symbionts positively influenced P.santalinus seedling growth which will be helpful for successful field establishment.     

Improvement of early growth of two tropical peat-swamp forest tree species Ploiarium alternifolium and Calophyllum hosei by two arbuscular mycorrhizal fungi under greenhouse conditions

Tropical peat-swamp forests are one of the largest near-surface reserves of terrestrial carbon. However, many peat-swamp forest tree species have resulted in the reduction due to over-exploitation, forest fires and conversion into agricultural land in Indonesia. The objective of this study was to determine the effects of two arbuscular mycorrhizal (AM) fungi, Glomus clarum and G. aggregatum, on the early growth of two slow-growing peat-swamp forest tree species, Ploiarium alternifolium and Calophyllum hosei, under greenhouse conditions. Cuttings of P. alternifolium and C. hosei were uninoculated or inoculated with G. clarum and G. aggregatum and grown under greenhouse conditions for 6 months. Percentage AM colonization, plant growth, phosphorus (P) concentration and survival rate were measured. The AM colonization of P. alternifolium and C. hosei ranged from 27 to 32% and 18 to 19%, respectively. Colonization by G. clarum and G. aggregatum increased shoot height, stem diameter, leaf number, and shoot and root dry weights. Cutting shoot P content were increased by AM fungal colonization. The survival rates of inoculated plants were higher (100%) than those of control plants (67%). The results suggest that inoculation with AM fungi improves early growth of P. alternifolium and C. hosei in a tropical peat-swamp forest and can therefore contribute to rehabilitation of peat-swamps.     

Improving drought tolerance of <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> seedlings by arbuscular mycorrhizas under glasshouse conditions

Effects of mycorrhizal association on improving tolerance of host plant under stress environments have received attentions in recent years. In this paper, six isolates of AMF (arbuscular mycorrhizal fungus) were inoculated to Casuarina equisetifolia seedlings under glasshouse conditions to investigate the effects of AMF on growth and drought tolerance of host plants. All the six isolates which belong to Glomus showed high mycorrhizal colonization (88.5–96.0%) with C. equisetifolia seedlings. Seedlings were subjected to drought stress without watering for 7 days and survival of the seedlings inoculated with Glomus caledonium Gc90068, G. versiforme Gv9004 and G. caledonium Gc90036 increased by 36.6, 23.3 and 16.6%, respectively compared with uninoculated seedlings. Limited influence of AMF on seedling height growth was found, but the effects of AMF on total biomass increment were very significant; the increment ranged from 25.7 to 118.9% compared with uninoculated treatment, and it was noted that AMF exerted more influences on root biomass than shoot biomass. Based on the changes in physiological and biochemical parameters among different treatments caused by drought stress, it was concluded that AM (arbuscular mycorrhizal) associations improve the drought tolerance of C. equisetifolia seedlings by means of some physiological and biochemical responses, such as lowering permeability of plasma membrane and MDA (malondialdehyde) contents, enhancing concentrations of P nutrition, soluble sugar, soluble protein and activities of POX (Peroxidase) of C. equisetifolia seedlings.     

乌桕幼苗耐旱性研究

采用PEC,6000模拟干旱胁迫和自然干旱胁迫两种方法,通过测定土壤含水量、叶片电导率、叶片丙二醛含量等指标,分析比较不同品种乌桕幼苗在干旱胁迫下的生理生化变化及耐旱性。结果表明：鸟桕幼苗优13和优24耐旱性较强,优23子代幼苗耐旱性最弱。PEC6000模拟干旱胁迫与自然干旱胁迫试验结果基本一致,可以在一定程度上反映正常的干旱胁迫。     

Pathogenicity testing of four Bursaphelenchus species on conifer seedlings under greenhouse conditions

The pinewood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer, J. Agric Res. 48, 1934, 949), Nickle (J. Nematol. 2, 1970, 375), is the causative agent of the pine wilt disease and causes serious damage to pine forests around the world. During a survey for the pinewood nematode, four other Bursaphelenchus species (Bursaphelenchus mucronatus, B. sexdentati, B. anamurius and B. vallesianus) were isolated from wilted pine trees in Turkey. To understand the effects of these Bursaphelenchus species on wilting of pine trees, a study was conducted under greenhouse conditions. Two‐year‐old seedlings of three pine species (Pinus nigra, P. brutia and P. pinea) and one cedar species (Cedrus libani) were used. Fifteen seedlings of each species were inoculated with nematodes and 10 seedlings of each species served as controls. The inoculum densities used for each seedling contained approximately 1000 (±100) nematodes of all life stages in 0.25 ml of distilled water. The first wilting symptoms were observed in the fifth week in all pine species but not in the cedar seedlings. All seeding mortality occurred between the 5th and 13th weeks of the study; no mortality was observed outside of this period. The most pathogenic nematode species was B. mucronatus, closely followed by the other species. The most susceptible seedling species was P. nigra, and C. libani was the most resistant species.     

Effects of shade on arbuscular mycorrhizal colonization and growth of crops and tree seedlings in Central India

The study was conducted to investigate the effects of different light intensities (25, 50, 67, and 100% of full sun [open]) on arbuscular mycorrhizal (AM) colonization and growth of two intercrops (a rainy season crop, Phaseolus mungo Roxb. var. PU-35 and a winter crop, Triticum aestivum L. var. WH-147) and seedlings of two multipurpose tree species (Eucalyptus tereticornis Sm. [Clone C-7, ITC, Bhadrachalam] and Albizia procera Benth.) of Central India. The results showed that various plant growth parameters viz., shoot length, dry weight and phosphorus (P) uptake were adversely affected by low light intensity. Inoculations with AM fungi (Acaulospora scrobiculata Trappe, Glomus intraradix Schenck & Smith and an unidentified Glomus species) increased the plant growth on account of all measured parameters under tested light conditions. Mycorrhizal efficiency of different AM fungi varied in narrow range. AM inoculants were more efficient at higher light intensity in above mentioned plant species, except wheat. Data on colonization of P. mungo, T. aestivum, E. tereticornis and A. procera showed that formation of arbuscules, vesicles and sporocarp was delayed by lower light intensity. Colonization index of host roots and spore counts increased with increase in light intensity during successive months after inoculation. Data on effect of light regimes on microclimate of net house showed that lux meter reading decreased as per grades of shading nets used during both rainy and winter seasons. With increase in light intensity, ambient temperature, soil surface temperature and sub surface temperature at 15 cm depth increased, except that the ambient and soil surface temperature in control (open) were slightly lower than net house observations during January and February. Value of ambient temperature varied in narrow range, with in treatments as compared to soil surface and sub soil surface temperature at 15 cm depth. Soil surface temperature at 25% of full sunlight was less than respective control values by 2–11°C and sub soil temperature at 15 cm depth was less by 4–12°C. The values of different microclimate parameters varied in narrower range during winter season as compared to rainy season. While ranking the importance of two factors studied—light and AM fungi—for their effect on the growth and P uptake by different plant species, inoculations with AM fungi came in the first place (explained 50–82% variation) and light substantially increased the values of R ² in stepwise regression analysis (forward selection). The results suggest that AM inoculation may enhance the growth and P uptake of intercrops under tree shade and the tree canopy management is likely to increase the efficiency of AM inoculants in agroforestry systems. Use of excessive shading (25% of full sun or more) in nurseries may be avoided and PAR (photosynthetically active radiation) lamps may be used to increase growth and colonization index of tree seedlings.     

赤松幼苗接种菌根真菌生长效应的初步研究

以赤松幼苗接种松茸菌进行盆栽和圃地栽培试验,研究菌根菌感染数量和菌根菌对苗木生长效应的影响。结果表明:在盆栽条件下,三种处理根系菌根真菌的感染指数分别为80、50、3,截根接种和不截根接种分别为对照的26.7倍和16.7倍,且截根处理是不截根的1.6倍;幼苗苗高、地径生长量显著提高,干重比对照分别增加33.3%和18.5%。在圃地条件下,截根接种与不截根接种的幼苗苗高、地径生长量比对照分别提高5.4%、4.2%和14.9%、6.9%。     

铁皮石斛优良共生菌的抗旱机理

为阐明细胞膜保护酶在菌根提高铁皮石斛抗旱能力过程中的作用,采用模拟自然干旱胁迫的方法,对胁迫过程中菌根化铁皮石斛细胞膜保护酶的活性变化进行研究。结果表明:铁皮石斛菌根真菌(JSAFC003、JSAFC004)能够在一定程度上提高植株的抗旱能力,SOD、POD活性与植株抗旱能力呈正相关,MDA含量与植株抗旱能力呈负相关,表明细胞膜保护酶的调节作用在菌根提高铁皮石斛抗旱能力过程中发挥了一定作用。     

Frost tolerance of two-year-old Picea glauca seedlings grown under different irrigation regimes in a forest nursery

Abstract

This study examined the impact of increased irrigation efficiency on the hardening and frost tolerance of 2-year-old containerized white spruce seedlings in the context of groundwater protection, irrigation management and the maintenance of seedling quality in northern climates. The seedlings were grown under three different irrigation regimes (IR =30%, 40% and 55% v/v; cm³ H₂O/cm³ substrate) and were hardened under conditions of natural photoperiod and temperature. After being subjected to artificial frost tests on four sampling dates during autumn, the seedlings were compared for bud development and frost tolerance. IR had no influence on frost tolerance as determined by measurements of physiological (electrolyte leakage, root water loss) and morphological (shoot damage, root initiation) variables. At the end of the second growing season, there was no significant difference between IRs in seedling height, root collar diameter, shoot dry mass and root dry mass. The results indicate that the amount of water applied to large-dimension 2-year-old white spruce seedlings during the growing season can be significantly decreased without prematurely impeding their growth or hindering their acquisition of frost tolerance.     

模拟不同程度酸雨对秃瓣杜英和青冈光合生理特征的影响

为比较秃瓣杜英Elaeocarpus glabripetalus和青冈Cyclobalanopsis glauca对酸雨胁迫的抗性强弱及差异,通过盆栽法,以蒸馏水(pH值7.0)处理作为对照组,研究在轻度酸雨(pH值5.6)、重度酸雨(pH值2.5)胁迫下,秃瓣杜英和青冈的光合指标、叶绿素和生物量差异。结果表明:1)在无酸雨胁迫下,秃瓣杜英和青冈的最大净光合速率(Pnmax)、暗呼吸速率(Rd)、光饱和点(LSP)、光补偿点(LCP)无显著差异。2)在轻度酸雨胁迫下,秃瓣杜英的Pnmax和LSP显著升高(P <0.05),叶绿素a、叶绿素b、叶绿素a+b的含量以及茎干质量、根干质量、总干质量指标都显著下降(P <0.05),其他参数无显著变化;青冈的Pnmax、Rd、LSP、叶绿素a、叶绿素b和叶绿素a+b的含量以及叶干质量、根干质量、总干质量都显著下降(P <0.05),其他参数无显著变化。3)在重度酸雨胁迫下,秃瓣杜英的Pnmax和LSP进一步升高(P <0.05),叶绿素a、叶绿素b和叶绿素a+b的含量以及生物量指标都进一步显著下降(P <0.05),Rd和LCP出现显著下降(P <0.05),其他参数无显著变化;青冈幼苗的Pnmax、Rd、LSP以及叶干质量、根干质量、总干质量指标都显著低于对照组(P <0.05),但叶绿素a含量显著增加(P <0.05),其余参数无显著变化。综上可得,秃瓣杜英与青冈相比更能适应在酸雨环境下生存,具有更为成熟的酸雨防御机制,而青冈对酸雨表现更为敏感。     

The arbuscular mycorrhizal fungi status of selected tree nurseries in the Ethiopian highlands

We investigated the arbuscular mycorrhizal fungi(AMF) status of ten nurseries suitable for restoration of dry evergreen Afromontane forests in Ethiopia. We quantified AMF root colonization(RC) and spore abundance(SA) in seedlings of nine native tree species namely Acacia abyssinica Hochst. ex Benth., Cordia africana Lam., Dovyalis abyssinica(A. Rich.) Warb., H agenia abyssinica J.F. Gmel., Juniperus procera Hochst. ex Endl., Millettia ferruginea(Hochst.) Baker, Olea europaea L. subsp. c uspidata(Wall. ex G. Don) Cif., Podocarpus falcatus(Thunb.) R. Br. ex Mirb. and Prunus africana(Hook. f.) Kalkman. We used the ink and vinegar method to stain AMF in roots. RC levels ranged from 8.00 to 99.67% and were generally higher than the RC levels reported from other similar nurseries in Ethiopia. SA levels ranged from 1 to 25 spores g~(-1) and werecomparable with some reports from the field in Ethiopia but they were lower than levels reported by another similar study. RC was more affected by host species than nursery location, while the reverse was true for SA. The results also showed that nursery management could improve AMF status among seedlings. When all nursery tree species were considered, RC and SA levels were unrelated. No strong correlation existed between the nursery management variables considered and RC or SA. However, considering C. africana, J. procera and P. falcatus separately, RC-age(r_s = 0.829, P = 0.042) correlation for O. europaea and RC-pot diameter( r_s = 0.820, P = 0.046), RC-pot volume( r_s = 0.928, P = 0.008) and SA-age( r_s = 0.943, P = 0.005) correlations for C. africana, were significant, strong and positive. Generally, most of the tree species and particularly, early-mid successional tree species had sufficient AMF inoculum. Hence, only the mid-late successional tree species; J. procera, P. falcatus, and P. africana may require AMF inoculation, preferably, during filed planting. Based on our results, age and pot volume were identified to be important variables potentially affecting RC and SA. To better understand the effects of these and other nursery management variables, additional study is required. We demonstrated for the first time that black Hero ink is suitable for staining root AMF and can be used in future AMF research.     

虎榛子几种菌根苗抗旱机制的研究

选用6个外生菌根菌株为接种体,分别对2个月龄虎榛子实生苗进行接种,培养4个月菌根感染率均超过40.8%.测定各处理苗木生物量、膜透性、SOD活性、MDA含量、叶绿素含量等指标,结果表明:彩色豆马勃、土生空团菌是以提高植物组织水势、SOD活性、降低MDA含量、减轻膜伤害程度、增加根冠比等机制来增强苗木的抗旱性,从而推迟苗木的萎蔫时间与延长干旱临界致死时间;厚环粘盖牛肝菌及点柄粘盖牛肝菌是通过提高苗木SOD活性和脯氨酸含量、降低MDA含量等机制来提高苗木的抗旱性;而卷边桩菇则是通过促进苗木的生长、增强苗木的生长势、降低苗木膜伤害程度、提高SOD活性和脯氨酸浓度、降低MDA含量等多种机制提高苗木的抗旱性.     

光照强度对青冈栎容器苗生长和生理特征的影响

研究不同光照强度(100％,60％,40％,20％,5％透光率)青冈栎容器苗形态和生理特征.结果表明:不同光照强度下,青冈栎容器苗地径、生物量、质量指数等参数差异达显著水平,其值由高到低分别为100％,60％,40％,20％,5％处理.随着透光率的增加,Chla/Chlb,Car/Chl、根质量比、比叶质量呈现上升趋势,色素(Chla,Chlb,Car)含量、比叶面积、叶质量比呈现下降趋势.遮荫明显增加青冈栎叶片电子传递的量子效率(ΦPSⅡ)和光化学猝灭系数(qP),全光照处理青冈栎叶片ΦPSⅡ只有0.131,而5％光强的处理中叶片ΦPSⅡ达到0.701,5％光强的处理中叶片qP为0.925,全光照下的处理中叶片qP为0.32.遮荫降低非光化学猝灭系数(NPQ),全光照处理青冈栎叶片非光化学猝灭系数NPQ为2.54,而5％透光率处理非光化学猝灭系数为0.16.随着透光率的提高,青冈栎叶片丙二醛( MDA)含量呈现下降趋势,游离脯氨酸含量(Pro)呈上升趋势.青冈栎为喜阳性树种,但也具有耐荫性.     

桂林岩溶石山青冈栎种群的结构特征

通过取样凋查,对桂林岩溶石山青冈栎种群进行统计,绘制了其种群径级与高度级结构图和存活曲线,分析种群的结构特征.结果表明,青冈栎种群幼苗极多,但死亡率极高,因而表现出种群前期下降,后期趋于稳定的特点;青冈栎种群的存活曲线接近于Deevey Ⅱ型,表现出稳定型种群特征;青冈栎种群的自然生长更新良好,可通过自我调节能力保持种群的稳定性.     

土著菌根真菌对西南桦无性系幼苗光合生理的影响

西南桦是一个典型的菌根营养型树种。揭示土著菌根真菌侵染对其幼苗光合作用的影响,旨在为菌根化幼苗的培育提供科学依据。以西南桦4个无性系组培苗为材料,应用12个西南桦人工林样地内表土(编号为S1、S2、S3,…,S12)作为接种剂和育苗基质开展盆栽试验,分析各土接种处理及无性系之间幼苗叶绿素含量、光合参数以及叶绿素荧光参数的差异。结果表明:1)12个土接种处理间幼苗叶绿素含量、光合参数以及叶绿素荧光参数差异显著,其中S12处理的叶绿素含量、净光合速率、气孔导度、蒸腾速率和水分利用效率以及Fv、Fv/Fm、ΦPSⅡ和ETR均显著高于其它处理,而叶绿素a与b含量的比值以及胞间CO2浓度显著低于其它处理;2)FB4、BY1、FB4+等3个无性系之间绝大部分光合生理指标差异不显著,而显著高于无性系A5,仅气孔导度和Fv/Fm在4个无性系之间差异不显著;3)相关分析亦显示,各土接种处理的西南桦幼苗总叶绿素含量、净光合速率、水分利用效率、PSⅡ最大光化学效率和实际光化学效率与其土著菌根侵染率均呈正相关,且绝大多数相关性达到显著或极显著水平。     

孟加拉国Madhupur林区内不同森林树种中丛枝菌根多样性的研究

从 Madhupur 林区的不同地点采集了 Acacia auriculi-formis A. Cunn. ex Benth., A. mangium Wild., Artocarpus het-erophyllus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Euca-lyptus camaldulensis Dehnn., Hevea brasiliensis (Wild. ex Juss) Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. 8个树种的根和根际土。采用简单常规的根围土壤真菌孢子分离、形态鉴定和树木细根染色、显微镜观察等方法,进行了孟加拉国Madhupur林区内不同森林树种中丛枝菌根多样性的研究。图2表2参46。     

Biodiversity of arbuscular mycorrhizal fungi in different trees of madhupur forest, Bangladesh

Roots and rhizosphere soils of Acacia auriculiformis A. Cunn. ex Benth., A. mangium Wild., Artocarpus heterophyUus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Eucalyptus camaldulensis Dehnn., Hevea brasiliensis （Wild. ex Juss） Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. were collected from different locations of Madhupur forest area to study the biodiversity of Arbuscular Mycorrhizal （AM） fungal colonization and spore population. All the plants showed AM colonization. Out of eight selected plants, mycelial colonization was lowest in the roots of A. heterophyllus （22%） and the highest was in the roots of H. brasiliensis （78%）. Mycelial intensity was observed poor （25%-77%） and moderate （23%-57%） in all plants species and abundant （11%-40%） was in most of the plant species. Vesicular colonization was observed in five plant species. The lowest was recorded in E. camaldulensis （4%） and the highest was in H. brasiliensis （21%）. Poor （24%-56%）, moderate （16%-100%） and abundant （11%-40%） type of vesicular intensity were observed. Arbuscular colonization was observed in three plants. The highest was in A. mangium （72%） and the lowest was in S. macrophylla （17%）. Arbuscular intensity was recorded as poor （12%-44%）, moderate （22%-100%） and abundant （4%-47%）. The highest AM fungal spore population was in A. auriculiformis （714） and the lowest was in D. sissoo （102）. Five AM fungal genera were recorded. Glomus was found to be dominant. A few spores remained unidentified. Significant correlation was observed between percent coloniza- tion and spore population. The results of the present study indicate the occurrence of AM fungi and the mycotrophism of the plants of Madhupur forest area and the applicability of AM technology in the forest management of Madhupur forest.